January/February 2010 - GEOSTRATA - Geo

Transcription

January/February 2010
Geo-Strata
Geo-Analysis,
Modeling and
Design
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th
44 U.S. Rock Mechanics Symposium
Salt Lake City, Utah USA
June 27-30, 2010
Geomechanics Workshop (free with Registration)
Dr. Priscilla Nelson-Moderator
Dr. Don Banks
Dr. John Curran
Dr. Maurice Dusseault
Dr. Richard Goodman
Dr. William Pariseau
Over 400 Abstracts Submitted
Opening Reception—Richard Robbins
“Advancements in Tunnel Boring”
Keynote—Prof. John Hudson
“Rocky Rambles through Caves, Cathedrals and Caverns”
Goodman Geologic Hazards Tour
Professor Richard Goodman and Dr. Richard Allis
Commercial Exhibits-Video Presentations
Tours:
Kennecott Copper Mine and TerraTek
Golden Spike Monument, The Nature Conservancy Great Salt Lake Project and the Spiral Jetty
Park City, Olympic Winter Park, Factory Outlet Mall
Mormon Genealogy Library and Temple Square
Registration online at www.armasymposium.org or
1-703-683-1808, Peter Smeallie / ARMA Executive Director
Figure 4. Shear stiffness degradation of London clay.
1
Features
VO LU M E 1 4 l I S S U E 1
Shear Stiffness
nonlinear elastic
CAU compression test
CAU extension test
0.01 0.1
1.0
Shear strain (%)
16 It’s All the RAGE
By D.V. Griffiths, Ph.D., P.E., F.ASCE and
Gordon A. Fenton, Ph.D., P.Eng., M.ASCE
32
22 Using Inversion to Improve Prediction in
Geoenvironmental Engineering
By Craig H. Benson, Ph.D., P.E., D.GE, F.ASCE and
Ronald J. Breitmeyer
28 Using Numerical Analysis in Geotechnical
Engineering Practice
By Lidija Zdravkovic’, Ph.D., DIC and
David M. Potts, Ph.D., DSc, FREng
ismic Data
. Seismic data indicates poaults in the reservoir, but not
ock (at top).
ons of predomacture orientae shown on FMI
bottom).
ourtesy
O2 JIP).
36 Advancing the Practice of Levee Analysis
No potential faults
37
By Scott Anderson, P.E., M.ASCE
42 CO2 Sequestration: Fractures Are Enabling
Clean Energy Options
By Joseph Morris, Ph.D., and Laura Pyrak-Nolte, Ph.D.
ON THE COVER:
A voxelization of aerial laser scanning of downtown Dublin. It is a critical step in the
auto-generation of city-scale, finite element models for the prediction of tunnel-
42
2
43
Potential
faults
Geo -Stra ta l geoins t it ut e. or g
induced subsidence along the proposed metro route. Image by Tommy Hinks,
Debra Laefer, and Hamish Carr funded by Science Foundation Ireland.
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Departments
08 Thoughts from the President
10 From the Editorial Board
14 Commentary: The Role of Analysis and Modeling in
21
Geotechnical Design in the 21st Century
By Rodrigo Salgado, Ph.D., P.E., M.ASCE, and
Patrick J. Fox, Ph.D., P.E., M.ASCE
21 GeoPoem
49 GeoCurmudgeon
52 CoreBits
49
WHO’S WHO AT GEO-STRATA
EDITORIAL BOARD
James L. Withiam, Ph.D., P.E. , D.GE
D’Appolonia
412.856.9440
[email protected]
N. Catherine Bazán-Arias, Ph.D., P.E.
DiGioia, Gray & Associates, LLC
412.372.4500 ext. 119
[email protected]
Jeff Dunn, Ph.D., P.E., G.E.
Kleinfelder, Inc.
510.628.9000
[email protected]
Debra F. Laefer, Ph.D.
University College of Dublin
011.353.86.343.3088
[email protected]
William K. Petersen, P.E.
URS Corporation
215.390.2157
[email protected]
2010 G-I BOARD OF
GOVERNORS
Edward Kavazanjian, Jr., Ph.D., P.E., D.GE,
President
Jean-Louis Briaud, Ph.D., P.E., D.GE, Past
President
Larry P. Jedele, P.E., Treasurer
Veronica L. Streich, P.E.
HNTB Corporation
414.359.2300
[email protected]
Craig H. Benson, Ph.D., P.E., D.GE
Bruce Gossett
Publisher
703.295.6311
Philip G. King, P.E., D.GE
William M. Camp, III, P.E., D.GE
Moustafa A. Gouda, P.E., F.ASCE, D.GE
G - I S TA F F
Carol W. Bowers, P.G., CAE, IOM
Director
[email protected]
Linda R. Bayer, IOM
Manager and Production
[email protected]
Suzanne Davenport
Content Coordinator
[email protected]
Carol W. Bowers * P.G., CAE, IOM, Secretary
Dianne Vance
Director of Advertising
703.295.6234
*ex-officio, non-voting member
Geo-Institute Website
www.geoinstitute.org
ADVERTISING
SALES MANAGERS
Jennifer Wirz
214.291.3652
Ellen Tucker
214.291.3661
Erin Ladd
214.291.3653
Jeff Sanderson
703.295.6107
Geo-Strata is a forum for the free expression and interchange of ideas. The opinions and positions stated within are those of the authors, and not necessarily those of
Geo-Strata, the Geo-Institute, or the American Society of Civil Engineers (ASCE). Geo-Strata—ISSN 1529-2975—is published bi-monthly by ASCE, 1801 Alexander Bell Drive,
Reston, VA 20191-4400 and is a free ASCE/Geo-Institute membership benefit, not available by subscription. ADDRESS CHANGES: ASCE/G-I members should e-mail [email protected], or click on
“My Profile” at asce.org. Copyright © 2010 by the American Society of Civil Engineers. All rights reserved. Materials may not be reproduced or translated without written permission from ASCE.
Periodicals postage paid at Herndon, VA, and at additional mailing offices. POSTMASTER: Send address changes to Geo-Strata, 1801 Alexander Bell Drive, Reston, VA 20191-4400.
4
Ge o-Strata l geoins t it ut e. or g
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D A T A.O N
PU R POSE.
Letters to the Editor
November/December 2009
I just wanted to let you know how
much I enjoyed your article “Carving
the World’s Largest Rock Monument.” You
really captured the essence of the project.
Fascinating!
other “patching,” the prominence finally
came crashing down. This occurred
many years after I had moved back west.
It was a sad day for those of us who were
so accustomed to seeing this impressive
natural visage daily.
I moved from Boulder to Franconia,
New Hampshire many years ago to
teach at Franconia College. There was
an iconic natural rock formation of a
“face” on Cannon Mountain in the White
Mountains, located at the top of the pass
approaching Franconia called “The Old
Man of the Mountain.” Unfortunately it
succumbed to the forces of nature, mostly
water seepage in fractured rock, and, after
many years of rock bolting, grouting and
Thanks to your well crafted article,
I now look forward to seeing ol‘ Chief
Crazy Horse in person one of these days.
S. Scot Litke
Publications Manager, ADSC
Dallas, TX
“The Old Man of the Mountain”
Designing Roads, Bridges, and Embankments
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Visit geo-slope.com/construction to see example analyses that have been
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6
Thoughts from the President
Ed Kavazanjian, Ph.D., P.E., D.GE
Predicting (or Inventing) the Future
My morning radio station used to have a news
commentator, Scoop Nisker, who closed his newscasts
with the suggestion that “If you don’t like the news, go out
and make some of your own.” To paraphrase Scoop, “If
you are concerned about the future,
go out and create one that is to your
liking.” Or, to quote Alan Kay, “The
best way to predict the future is to
invent it.” (Alan Kay was one of the
inventors of Smalltalk, the inspiration
and technical basis for the MacIntosh
and subsequent windowing-based
operating systems).
The Geo-Institute is engaged in
a number of activities designed to
invent the future we want for our
organization. But for any of these
activities to be successful, they require
the active engagement of our members
through volunteer activities. You can
help create the future you would like
for the G-I by becoming more active
in your local ASCE geotechnical
group (which hopefully is either
currently a local G-I chapter or on
its way to becoming one), joining
a technical committee on the national level (you can
download an application at http://content.geoinstitute.org/
committees/committees.html, or by volunteering to serve in
one of the many other G-I activities that rely upon member
participation, e.g. on a Board of Governor task force,
the organizing committee for an upcoming G-I annual
Congress or specialty conference, or the Editorial Board for
one of our journals or Geo-Strata. You can also encourage
and support involvement by your colleagues and employees
in these G-I activities.
One of the most important recent initiatives designed to
invent the best possible future for the Geo-Institute is our
Student and Younger Member Participation Committee.
This is a Board-level committee initially formed as the
Student Participation Committee but recently expanded in
scope to include younger members. The long-term success
of any organization relies upon a continuing stream of new
blood and fresh ideas, and this committee is designed to
foster the development of that stream. The Committee has
made impressive progress towards that goal in its first few
years of operation, including a significant enhancement of
8
student-related activities at the G-I annual Congress. The
GeoFlorida Congress will include a reception for student
attendees with our Organizational Members, a Career
Fair, increased participation in the MSE wall competition
for students, and a student poster session that will be
tied in with the MSE wall competition. Expansion of the
scope of the Committee to include
younger members will help provide
a seamless transition from student
membership to active engagement
in the Geo-Institute for the next
generation of volunteers and leaders
in our Society.
Other recent student-related
initiatives of the G-I include the
expansion of the number of G-I
Graduate Student Organizations
(which now stands at eight) and the
formation of the Student Presidential
Group by Jean-Louis Briaud during
his presidency (and continued during
my term). These initiatives represent
important steps in developing the
next generation of leaders for the G-I
and providing some fresh, new ideas
for engaging our student and younger
members.
To help provide a reliable source of funding for
our student activities, the Board of Governors created
a restricted Student Participation Fund and obtained
permission from ASCE to channel all of the voluntary
contributions made to the G-I with your annual dues
payment into this fund. If you have not yet made your
dues payment, please consider a voluntary contribution.
If you have already paid your dues and missed the
opportunity to contribute to the fund, you can make a
direct contribution through the G-I website. Click on
the “donate online” link in the associated story at www.
geoinstitute.org. Your contributions, as well as the activities
described above, will help us continue to develop the next
generation of volunteers and leaders of our organization,
thereby inventing the future we want for the Geo-Institute.
Ed Kavazanjian, Ph.D., P.E., D.GE
President, Geo-Institute of ASCE
From the Editorial Board
Analysis, modeling, and design; in many ways that’s the
essence of what we do as a profession. Analysis, modeling,
and design is also the theme of this issue and GeoFlorida
2010 to be held in West Palm Beach in February. As many
of the articles in this issue recount, our ever-improving
computational capabilities must be used with care, for just
as we once used back-of-the-envelope checks of our slide
rule analyses, we must take at least equivalent care with
our analytical tools. This issue tries to capture some of
these concerns and some of what you’ll learn if you attend
GeoFlorida 2010.
What’s Inside?
At the time of Terzaghi’s seminal
text Theoretical Soil Mechanics and
for about the next 20 years into
the early 1960s, the discipline was
dominated by theory supported by
simplified methods of analysis and
empiricism. Since then, we have
seen computational power continue
to increase, constitutive models
developed that realistically model soil
behavior, and numerical methods
evolve to analyze the boundary-value
problems of geomechanics. But where
is this all headed, especially for more
routine projects with small budgets? Rodrigo Salgado and
Pat Fox offer their perspective in this issue’s commentary,
“The Role of Analysis and Modeling in Geotechnical Design
in the 21st Century.”
Risk assessment in geotechnical engineering, or RAGE,
is a rapidly growing area of interest and study. This is
driven by the inherent uncertainty of geologic materials
and our ever-improving probabilistic tools to characterize
and quantify uncertainty and apply them in geotechnical
analysis and design. In “It’s All the RAGE,” Vaughan
Griffiths and Gordon Fenton describe some of these tools
and their ever-increasing importance in more conventional
projects where engineers are increasingly required to
explicitly consider risk and reliability in their analyses and
designs.
The processing capability of today’s computers and
the availability of sophisticated numerical models permit
the solution of complex problems in geoenvironmental
engineering. But how realistic are the solutions they provide
and how can they be tested? In “Using Inversion to Improve
Prediction in Geoenvironmental Engineering,” Craig
Benson and Ronald Breitmeyer describe how inversion
10
(running a model “in reverse” to find the set of input
parameters that result in the prediction that most closely
resembles observed behavior) can be a powerful tool to
improve parameterization.
A number of specialist geotechnical software packages
are currently available. They usually differ in the level
of sophistication and in the way in which constitutive
models, boundary conditions, and numerical solvers
are implemented so it is not unusual to obtain different
answers to the same problem from
different software. For a successful
analysis, it is also important for the
user to understand how the applied
software works and what might be
going on in the computer black box.
Lidija Zdravković and David Potts
discuss some of the problems and
solutions involved with one of the
simplest geotechnical constitutive
models, the linear elastic-plastic MohrCoulomb model in “Using Numerical
Analysis in Geotechnical Engineering
Practice.”
Recent flood zone mapping shows
that 42 miles of levees containing
the Sacramento Natomas Basin do
not provide a 100-year level of flood
protection. An on-going engineering evaluation of levees
is providing a unique opportunity to improve the state
of geotechnical practice in terms of levee analysis and
design. In “Advancing the Practice of Levee Analysis,”
Scott Anderson describes side-by-side comparisons of
widely used groundwater and slope stability modeling and
analysis software to assess short- and long-term scenarios,
conduct probabilistic vulnerability studies to quantify
relative reliability of embankments, and develop accurate,
efficient, and presentation-ready answers to highly complex
problems.
Our last article is not about this issue’s theme, but
rather last issue’s theme, rock mechanics. Sequestration of
carbon dioxide in deep geologic reservoirs has emerged as a
method to enable substantial reductions in greenhouse gas
emissions. Joe Morris and Laura Pyrak-Nolte introduce the
process and the importance of geologic characterization in
“CO2 Sequestration: Fractures Are Enabling Clean Energy
Options.”
If you could choose another time to be a geotechnical
(or soil mechanics) engineer, when would that be? Our
Geo-Poet has chosen 1965. Read “Confessions of a Young
Luddite” to find out why. And
how many times have you been
told that perception is reality? Our
GeoCurmudgeon “perceives” that
geoprofessionals don’t get the respect
they should because we don’t show
up and speak up before the public to
influence the public discourse. Please
check them out and let us know your
preferred geo-era and what you’ve
done to show up and speak up.
This message was prepared by Jim
Withiam, Editor-in-Chief.
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phone at 800.548.ASCE (2723).
Geo-Strata l geoinstitute.org
11
A Diplomate of Geotechnical Engineering
Profile…
Blaine Leonard, P.E., D.GE., F.ASCE,
President ASCE
Why D.GE
Certification?
Certification is
a demonstration of
expertise and experience
in a specialized field. It
sets us apart from those
who have not attained
this level.
Ideally, clients will
recognize the value of
specialty certification,
and require it as part of their selection processes. Since
certification of geo-professionals is still fairly young, we
haven’t seen that ideal reached yet. I hope that someday we
will.
When you enter a doctor’s office, you will often notice
a Board Certification designation hanging on the wall. We
are more comfortable after seeing that, knowing that we are
about to be diagnosed and treated by someone with special
expertise. It should be no different in engineering; clients
should recognize and require the D.GE credential.
My Background
My practice has been quite broad. I have been in both
the private and public sectors. I have
practiced geotechnical engineering
on a variety of projects, and in
many other civil engineering areas.
The geotechnical background
has always been useful to me.
Although I am interested in
many things, my passion is still
geotechnical engineering, and I
find the most satisfaction on those
projects.
What D.GE Certification
Has Meant to Me
Specialized Site Investigation Services
West 1-800-567-7969 • East 1-800-504-1116
www.conetec.com • [email protected]
Vancouver, BC • Edmonton, AB • Salt Lake City, UT • West Berlin, NJ • Charles City, VA
12
I will have to admit that being
a D.GE has not as yet provided
me any direct benefit over the past
year. However, I am proud to hold
that credential, and to display it on
documents that bear my name. As I
continue in my career, I am sure that
it will provide an indication of my
background and focus, and will help
me in the projects I pursue. I will
encourage others who are qualified
to seek specialty certification, and
will promote its use in selection
processes.”
Commentary: The Role of Analysis and Modeling in
Geotechnical Design in the 21st Century
By Rodrigo Salgado, Ph.D., P.E., M.ASCE, and Patrick J. Fox, Ph.D., P.E., M.ASCE
With GeoFlorida 2010, which focuses on analysis,
modeling, and design, fast approaching, it is worthwhile
to consider the role that analysis or “theory” in its various
forms has played and will play in design in the future. For
the purposes of this discussion, we find it convenient to
mark the beginning of our discipline
with the publication of Karl
Terzaghi’s Theoretical Soil Mechanics in
1943; this means that, at 67 years old
in 2010, geotechnical engineering is
a bit younger than some of its more
senior professionals!
Terzaghi’s book was the
first organized effort to catalog
the theories that helped guide
geotechnical design at the time. If we
examine the status of theory in the
1940s and 1950s, before the age of
computers, the prevalent method of
analysis was limit equilibrium, and
soil was modeled as either linear
elastic or perfectly plastic (according
to Terzaghi, a soil had to be modeled
as an “ideal sand” or “ideal clay,”
for it was impossible to capture
mathematically the complexity of
soil behavior). In contrast, today
we have considerable and growing
computational power, constitutive
models that can realistically model soil behavior, and a
variety of analytical methods, chief among them the finite
element method, to analyze the boundary-value problems
of geomechanics.
The enormous progress that has taken place in
theoretical soil mechanics (particularly in the last 30 years)
has yet to be substantially integrated into practice, and
thus the role that theory plays in the design process is not
significantly different from what it was decades ago. One of
the reasons for this relatively slow integration of advances
in theory into practice is the dominant philosophy followed
in some of the earlier geotechnical texts. Although Terzaghi
had a conflicted relationship with the value of theory in soil
mechanics, sometimes pointing out how essential it was
and sometimes downplaying its value, the approach taken
in both Theoretical Soil Mechanics and Soil Mechanics in
Engineering Practice that theory provides some guidance but,
in the end, solutions are mostly shaped by judgment and
empiricism, has attracted the largest audience.
14
While this role of theory was certainly appropriate for an
engineer of the 1950s, when soil models, site investigation
methods, and computational methods were all too
crude to provide accurate solutions for real problems,
an upgrade of the role of theory in the design process is
appropriate with the tools available
today. Given the limited scientific
knowledge and limited software
and testing resources of the early
days of geotechnical engineering,
empiricism was all an engineer
had available. While empiricism
can provide acceptable solutions, it
must be moderated by judgment,
particularly when one is operating
outside the range of conditions used
to develop the empirical rules. But
today the question is whether theory
has developed to the point that it
can take on a greater role in practice
than it has in the past, thereby also
redefining the roles of empirical
precedent and judgment.
An examination of the literature
shows: 1) that the behavior of soil at
the elemental level is reproducible
using constitutive models that have
parameters with physical meaning
and that can be determined
relatively simply; 2) that computational techniques exist
to integrate these constitutive models and also handle the
nonlinearities that appear in most geotechnical boundaryvalue problems and, most importantly; 3) that predictions
made with analyses using these models and techniques
match measurements in well-controlled experiments. Thus,
if the essential ingredients of quality site characterization
and testing are added to this mix, conditions are in
place for design work to be conducted at a high level of
sophistication. Of course, judgment still has a role in
the design process to prevent blunders, avoid the use of
inappropriate tools, and refine solutions. However, the role
of judgment would not be to replace calculation tools.
The technical problems that our profession is likely
to face in the future will be more challenging than in the
past. It is also obvious that most projects have insufficient
budget or time to allow for sophisticated analyses. So,
Continued on page 20
It’s All the RAGE
By D. V. Griffiths, Ph.D., P.E., F.ASCE and Gordon A. Fenton, Ph.D., P.Eng., M.ASCE
R
isk assessment in geotechnical engineering, or RAGE,
is an exciting and rapidly growing area of interest and study
for both geotechnical practitioners and academics. Evidence
of this growth is attested by increased sessions on the topic
at G-I symposia, new practitioner-oriented journals, recent
textbooks, and regularly scheduled ASCE Continuing
Education short courses.
Soils and rocks in their natural state are among the most
variable of engineering materials. Geotechnical engineers
often must “make do” with materials at a particular site. In
a perfect world with no economic constraints, numerous
boreholes would be drilled and multiple samples returned
to the laboratory for measurement of soil properties
such as permeability, compressibility, and shear strength.
Engineering designs following such a thorough site
characterization would lead to confident performance
predictions. In reality, rather limited site investigation data
are available and the traditional approach for dealing with
uncertainty in geotechnical design has been through the use
of characteristic values of the soil properties coupled with a
generous factor of safety.
If the multitude of data for one of the soil properties
from the “perfect world” site investigation were plotted as
a histogram, a broad range of values would be observed
in the form of a bell-shaped curve. The most likely values
of the property would be somewhere in the middle, but a
significant number of samples would display higher and
lower values. This variability, inherent in soils and rocks,
suggests that geotechnical systems are highly amenable to a
statistical interpretation.
This is quite a different philosophy to the traditional
approach: in the probabilistic approach, input soil
properties are characterized in terms of their means,
variances, and covariances, leading to estimates of the
probability of failure (pf) or reliability index (ß) of a
design. Specific examples might involve estimation of the
probability of failure of a slope, the probability of excessive
differential settlement of a foundation, or the probability of
excessive leakage from a reservoir.
Risk is defined as the probability of design failure
weighted by the consequences of design failure (e.g.,
fatalities, cost, and unacceptable performance). Design
16
of geotechnical systems will typically include a target
acceptable risk, defined as the risk that the stakeholders
consider acceptable under given conditions. The acceptable
risk built into a design will likely be much lower for a major
earth dam in a populated area than for an embankment
retaining an irrigation pond in a remote rural location.
Regardless of the type of project, however, risk assessment
is unavoidably quantitative in nature and an engineer
performing a risk assessment must ultimately develop
numerical estimates of pf..
Methods of Probabilistic Analysis
While there are several tools available for probabilistic
analysis in geotechnical engineering, event trees, the first
order reliability method, and the random order finite
element method of probabilistic analysis, are representative
of tools with increasing levels of complexity and
mathematical sophistication.
Level I: Event Trees. Event trees are typically used for
probabilistic analysis in practice, and are performed prior to
deciding whether more detailed mathematical or numerical
modeling is warranted. Agencies such as the Bureau of
Reclamation who deal regularly with critical geotechnical
structures, such as earth dams, use event trees to estimate
the probability of different modes of design failure.
Event trees consist of nodes and branches that must
be constructed carefully and adhere to certain rules to be
useful in calculations. From a starting node, two or more
branches leave. At the end of each branch there is another
node from which more branches may leave and go to
separate nodes. The idea is repeated from the newer nodes
as often as required to completely depict all possibilities.
A probability is associated with each branch and, for
all branches except those leaving the starting node, the
probabilities are conditional; that is, they are probabilities
of events occurring given that other events (earlier
branches) have already occurred.
Event trees can become quite complicated for complex
problems. Figure 1 presents a simple example for an
embankment potentially vulnerable in the event of an
earthquake or a flood. All the numbers on the figure
represent probabilities, which in practice are developed by
probabilistic models and/or an expert panel of engineers
based on experience and similar case histories.
Embankment Failure
Failure 0.3
Event Tree
Not Failure 0.7
Earthquake 0.1
Failure 0.2
Flood 0.3
Not Failure 0.8
Neither 0.6
Failure 0
Not Failure 1
Figure 1. A simple event tree showing conditional probabilities
that might lead to failure of an embankment.
where FS = qult/qall and qult is obtained from Terzaghi’s
bearing capacity equation. Let us assume that the width of
the footing (B), the soil unit weight (γ’), surface surcharge
(q) and groundwater conditions are confidently known
(deterministic), but that the shear strength parameters (c’,
tanΦ’) are uncertain and to be treated as random input
variables (stochastic), characterized by their means and
standard deviations (µc′,σc′) and (µtanφ′, σtanφ′).
A typical bivariate probability density function with
generic random variables x and y might look like the “hill”
shown in Figure 2a. Figure 2b shows a plan view of the
probability density function in normalized space (µ = 0, σ
= 1) together with contours of the reliability index ß, which
measures standard deviations units away from the mean.
For example, the contour marked ß = 1.5, represents the
locus of random variables 1.5 standard deviations away
from their mean values. Also shown on Figure 2b is the
performance function labeled FS = 1.
Probability Density Function
and Performance Function
The probability of a specific type of failure is found by
multiplying together the probabilities along the branches
that lead to that failure. From Figure 1, the probability of
failure due to an earthquake (pfeq) would be given by:
pfeq = 0.1 x 0.3 = 0.03
0.07
10
The starting point for a FORM analysis is a performance
function for the system under investigation. A performance
function separates safe from failure combinations of input
variables and is the locus of FS = 1. Usually, the function
is arranged such that if it is negative, failure conditions
are implied; if it is positive, safe conditions are implied. A
performance function may be based on a familiar equation
from classical geotechnical analysis or, if no convenient
function exists, it may be generated numerically using curve
fitting.
8
6
6
y
4
4
2
Plan view of a normalized pdf together
with a performance
function marked
FS=1 and the minimum reliability index
contour marked
β=0.6892.
0
Figure 2a.
Probability
density function (pdf) involving
two random variables
2
5
3.
3
1.5
5
2.
2
1
5
1.
.6892
0.5
.5
0
-.05
-1
-1.5
The performance function for a bearing capacity analysis
in which a strip footing is subjected to an allowable bearing
pressure (qall) might be written as:
x
Figure 2b.
2
0
▲
Normalized ln(tanϕʹ)
Level II: First Order Reliability Methods (FORM). This
method has gained significant attention in recent years as
a relatively simple way of obtaining probabilities of failure
for geotechnical systems involving random input variables.
The method is also easily run using familiar software such
as Excel.
10
8
▲
The total pf, regardless of cause, would be obtained by
adding together the branch products due to earthquake and
flood as:
pf = 0.1 x 0.3 + 0.3 x 0.2 = 0.09
1.0
FS=
-2
-2
-1.5
-1
-0.5

0
.05
1
1.5
2
Normalized lnCʹ
g = FS – 1
17
FORM is essentially an optimization method that
iteratively finds the most likely values of the random
variables that would result in failure. In Figure 2b, this
is given by the contour ß = 0.6982 that just touches the
performance function. The reliability index is easily
converted to a probability of failure through standard
cumulative distribution tables. In this case, ß = 0.6982
corresponds to pf = 0.243.
Random Finite Element Method (RFEM). This method
was developed by the authors in the early 1990s and
involves a combination of finite element and random field
methodologies with Monte-Carlo simulations. The method
is more computationally intensive than FORM but properly
accounts for spatial variability and correlation, which
recognizes that at any given site, soil properties are more
likely to have similar properties if they are located close
together rather than far apart. In particular, in addition to
the means and standard deviations of input parameters (as
required by FORM), RFEM also requires input of the spatial
correlation length, defined as the distance over which
properties tend to be positively correlated. Anisotropic
spatial correlation lengths can also be considered where the
horizontal spatial correlation length may be longer than in
the vertical direction.
An advantage of RFEM, which becomes especially clear
in the study of the collapse of soil masses, is its ability to
realistically allow the failure mechanism to “seek out” the
most critical and weakest path through the soil mass. This
can lead to quite convoluted failure mechanisms that are
significantly different to the classical mechanisms that occur
in homogeneous soils. More importantly, the “seeking
out” phenomenon, not easily accounted for by methods
such as FORM, generally gives lower factors of safety and
higher pf values than would be predicted by traditional, but
“incorrect,” mechanisms.
Figures 3a and 3b show, respectively, typical failure
mechanisms that might be displayed in two-dimensional
(2D) and three-dimensional (3D) slopes modeled by
RFEM. The 2D case represents a tailings dam with different
random materials in the embankment and the foundation.
Two different mechanisms have formed simultaneously
through the weaker soil formations, indicating a tendency
for rotational and horizontal sliding mechanisms. The 3D
case is of a long dam or levee in which spatial correlation
effects have led to a concentration of weaker soils at a
particular location resulting in a localized failure zone. The
pf predicted by a RFEM is simply the number of simulations
that fail divided by the total number of Monte-Carlo
simulations performed.
The Road to RAGE
Although probabilistic concepts have been utilized by
geotechnical engineering for many years, they have tended
to be confined to “high tech” projects such as offshore
and earthquake engineering where a statistical treatment
of loading (e.g., the 100-year event) was an essential
consideration. Nowadays, engineers are increasingly
required to explicitly consider risk and reliability in more
conventional investigations such as slopes and foundations.
Detailed probabilistic analysis of two different earth slopes
might conclude that the slope with the higher factor of
safety also has a higher probability of failure than the slope
with the lower factor of safety! Only a probabilistic method
could reveal such a counter-intuitive outcome.
The increased use of reliability-based design in
geotechnical engineering is also an incentive for a greater
awareness of probabilistic methods. These methods feed
directly into the choice of load and resistance factors
needed to achieve a target reliability level.
Figure 3. Typical RFEM simulations of slopes showing failure
mechanisms “seeking out” paths through the weakest soils. a) 2D
simulation of a tailings dam showing the development of two different
failure mechanisms. b) 3D simulation of a long dam or levee showing
a localized failure mechanism due to a zone of weaker soil.
18
Risk-based methodologies are here to stay because
they offer a more scientific and informative approach
to assessing the reliability of geotechnical designs.
Geotechnical engineers should become familiar with
these concepts and include some of them in their routine
“toolbox” for geotechnical analysis.
D. V. Griffiths, Ph.D., P.E., F.ASCE, is professor of Civil
Engineering at the Colorado School of Mines in Golden,
CO. Professor Griffiths’ research interests include numerical
and probabilistic methods in geotechnical engineering. He
offers regular ASCE Continuing Education short courses for
geotechnical engineers on these topics. He can be reached at:
[email protected]
Gordon A. Fenton, Ph.D., P.Eng., M.ASCE, is professor
in the Departments of Civil Engineering and Engineering
Mathematics at Dalhousie University in Halifax, Nova
Scotia, Canada. Dr. Fenton’s research interests include the
development of reliability-based geotechnical design provisions
and probabilistic modeling of geotechnical problems. He joins Dr.
Griffiths in the offering of short courses on these topics. He can
be reached at: [email protected]
Contracting Services
Commentary:
Continued from page 14
given these challenges, how can geotechnical engineers get
value from these developments in analysis and modeling?
One approach is for academics and researchers to produce
relatively simple and efficient tools and guidelines that can
be used for routine practice based on the results of highlevel analyses that are properly validated with high-quality
experimental data. This may very well be the path that the
discipline will follow. We already see such trends developing
among leading engineering firms and researchers. How fast
this or similar approaches take root will depend on those in
the practicing community who are open to embracing new
developments, on university professors who will take the
lead in producing and teaching the new methods and tools,
and on economics, which is the final arbiter as to the value
of how we use our time and talents for technical activities
going forward.
We believe that the new knowledge that has developed
in the last 67 years, and particularly in the last 30 years,
has tremendous value to the profession and can be used to
even greater advantage. In fact, that is the major premise for
GeoFlorida 2010. The conference’s
technical program will provide a
unique opportunity for engineers to
see the forefront of modern analyses
and numerical modeling methods
and to share their own experiences
and thoughts regarding further
development of these methods to
benefit the future of the discipline.
Rodrigo Salgado, Ph.D., P.E.,
M.ASCE, is professor of Civil
Engineering at Purdue University in
West Lafayette, In. Rodrigo is also
technical program chair of GeoFlorida
2010. He can be contacted at
[email protected]
Patrick J. Fox, Ph.D., P.E., M.ASCE,
is professor at the University of
California – San Diego. Patrick is also
conference chair for GeoFlorida 2010.
He can be contacted at
[email protected]
cetco.com/ccs
20
800.527.9948
Geo-Strata is interested in
hearing from you. Please
send your comments on this
commentary to
[email protected].
Confessions of a Young Luddite
By Mary C. Nodine, P.E.
If I could live in a different time
Of engineering history than mine,
I’d choose, say, 1965,
When drafting tables and compasses thrived
On desks adorned with calc pads and ink,
Rather than laptop computers, I think.
For in those simpler, carefree days
One could focus on the way
To calculate a safety factor
Uninterrupted by such matters
As slow networks and missing cables,
The proper font styles for titles and labels,
Windows, menus, commands and cells,
Popup email cries for help
And backing up her files, lest
She’s cursed with the Blue Screen of Death!
Yes, I think I’d like an office life
Void of technologic strife,
For old-school gadgets, tried and true
Have always been my favorite tools.
Fancy computer programs pale
When compared to my trusty engineer’s scale.
My poor heart sinks a bit for sure
On days it never leaves my drawer.
With it I measure any span,
Shrink a drawing and sketch a plan But it’s not a straightedge! Oh, the horror!
That’s what triangles are for.
It’s not just scales on which I’m hooked,
But maps and plans and old bound books.
To huddle in the library,
Study yellowed topography
And determine which bedrock formation
Underlies my planned foundation
Is sheer bliss. The hours fly by, it seems
Far from the glare of my monitor screen.
But despite my nostalgia, I always find
My desk planted firmly in 2009
With two monitors, mouse and Bluetooth keyboard
And the latest version of Microsoft Word.
My abilities, too, live in present day
Thanks to classes in CAD and VBA.
With only a slide rule, I’d have no clue
How to calculate two plus two.
But I admit that I love a well-thought-out
spreadsheet
That corrects in a second what I’d erase in a week.
And finding a critical circle is fun
With a stability program that takes seconds to run.
Perhaps I speak with so much heart
Of an era of which I was never a part
To quell my perceived inadequacy
At manipulating Civil 3D
Or worse, my utter lack of finesse
With a dead hard drive – but I digress.
We’re here, it’s now, the bar’s been raised.
A seepage analysis no longer takes days
And I certainly count myself lucky indeed
That edits to plans can be made with such speed.
Still, the best of times at work, to me,
Are when vellum graph paper features prominently
Alongside my compass, triangle and scale,
Colored pencils to distinguish siltstone from shale.
For soil’s not perfect and computers are nice,
But sometimes it’s best to be not-so-precise.
I’ll visit my clay, contemplate it at length,
Find the back of an envelope to calculate strength.
Then refreshed, I return to my laptop again,
An answer already sketched out in my brain.
Mary C. Nodine, P.E., is a geotechnical poet
and a project engineer with GEI Consultants, Inc.
in Boulder, CO. She can be reached at:
[email protected]
21
Using Inversion to Improve
Prediction in Geoenvironmental
Engineering
By Craig H. Benson, Ph.D., P.E., D.GE, F.ASCE and Ronald J. Breitmeyer
T
he processing capability available on today’s
desktop computers has revolutionized how problems are
approached in geoenvironmental engineering. Complex
non-linear problems can now be tackled using off-the-shelf
(OTS) software equipped with graphical user interfaces
(GUIs) that make model definition, data input, and
visualization of output extremely simple and convenient.
Some very sophisticated OTS software is available at no
cost. For example, the widely used HYDRUS1D code can be
downloaded from the internet (www.pcprogress.com).
mean square error). Automated algorithms for conducting
inversions exist in many OTS software packages. The
outcomes from inversion can also be used to assess the
conceptual model.
This software will simulate complex non-linear coupled
unsaturated water flow, heat transfer, and contaminant
transport in one dimension (1D) using the finite element
method. The code can also simulate geochemical processes,
colloidal transport, and soil-atmosphere interactions.
Perhaps most significant is the very fast processing
associated with the numerical methods and the convenient
input and rapid examination of output afforded by the
GUIs.
The output from today’s models can appear very
realistic. In fact, the output can appear so realistic that the
predictions may be confused with actual data. However,
predictions are not reality, and comparisons with field data
have shown that deviations from field conditions can be
substantial. Two factors having great impact on the realism
of the simulations are the conceptualization of the model
and the material properties used as input.
If field data are available, inversion can be used as
a powerful tool to select appropriate input parameters.
Inversion consists of running a model “in reverse” to find
the set of input parameters that results in the prediction
that most closely resembles the state or behavior observed
in the field. An inverse simulation generally consists of a
series of conventional (“forward”) simulations where the
input parameters are varied systematically over defined
ranges. Predictions from the forward simulations are
compared with the field data to identify the parameter
set that provides the optimal fit to the data (e.g., smallest
22
Figure 1. Schematic of lysimeter
Inversion Example
Inversion was used to determine appropriate hydraulic
properties and to identify shortcomings in a conceptual
model used to simulate variably saturated flow for design
of leachate recirculation systems for municipal solid waste
(MSW) landfills. Field data for the inversion were obtained
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from a large lysimeter (8.2 m tall and 2.4 m diameter)
constructed at a MSW landfill in southern Wisconsin. The
lysimeter was filled with MSW and instrumented with a
variety of sensors, including time domain reflectometry
probes to monitor water content and a dosing basin to
record outflow. Waste within the lysimeter was separated
into three layers and the hydraulic properties within each
layer were assumed to be homogeneous and isotropic
(construction records indicated that the MSW density
within a given layer was reasonably uniform). A schematic
showing the instrument locations in the lysimeter nest is
presented in Figure 1.
The lysimeter is dosed periodically by applying
approximately 1,800 L of leachate on the surface of the
lysimeter over a 15-minute period. A two-dimensional
model with radial symmetry was constructed in HYDRUS
to simulate flow in the lysimeter in response to leachate
dosing. Van Genuchten’s function was used to describe
the water retention curve (WRC) and the Van GenuchtenMualem function was used to define the unsaturated
hydraulic conductivity. A variable flux boundary was
applied at the surface to simulate the inflow of leachate
from dosing. The base of the lysimeter was assigned a unit
gradient boundary condition. Outflow from the lysimeter
and water contents recorded in the waste were used as the
data for the inversion.
Figure 2. WRCs and unsaturated hydraulic conductivity measured in the laboratory on MSW (top). Smooth lines are the
van Genuchten function (WRCs) or the van Genuchten-Mualem
function (hydraulic conductivity) (bottom).
Complimentary laboratory tests were conducted on
samples of the MSW to determine the saturated hydraulic
conductivity, WRCs for wetting and drying, and the
unsaturated hydraulic conductivity function. These tests
were conducted on MSW from the lysimeter that had
been shredded to < 25 mm. Rigid-wall permeameters were
used to determine the saturated hydraulic conductivity
and large-scale hanging columns were used to determine
WRCs. The unsaturated hydraulic conductivity function
was determined from the WRC data using the multi-
step outflow method. Examples of the WRCs and the
unsaturated hydraulic conductivity functions measured in
the laboratory are shown in Figure 2.
Hydraulic properties obtained from the laboratory tests
and from inversion are summarized in Table 1. Obtaining a
Table 1. Hydraulic Properties from the Laboratory and Obtained by the Inversion
Table 1. Hydraulic Properties from the Laboratory and Obtained by the Inversion
Laboratory-Measured
Hydraulic Properties
Layer
1
2
3
24
Density
(kN/m3)
11.2
8.2
7.8
Sat.
Hyd.
Cond.
(m/s)
3.1×10-9
2.3×10-7
5.0×10-7
ℓ
n
α
(kPa-1)
–8
–5
–5
1.3
1.3
1.3
0.5
1.8
1.9
Field Hydraulic Properties
Obtained by Inversion
Sat.
α
Hyd.
ℓ
n
(kPa-1)
Cond.
(m/s)
2.0×10-5 1.53
1.3
0.5
5.8×10-5 1.58
0.2
1.3
7.3×10-4 0.24
1.3
1.8
Figure 3. Measured
and predicted
water contents
and cumulative
outflow (top).
Predictions made
using hydraulic
properties
measured in
the laboratory
and obtained by
inversion (bottom).
reliable match between the model predictions and the
field data requires saturated hydraulic conductivities much
higher than those measured in the laboratory (the saturated
hydraulic conductivities obtained by inversion range from
two to nearly four orders of magnitude larger than those
measured in the laboratory). The pore interaction terms
obtained by inversion (ℓ = 0.24 to 1.53) are also very
different from those measured in the laboratory (ℓ = -5
to -8). In contrast, the WRC parameters α and n obtained
by inversion are comparable to those measured in the
laboratory.
Deficiency in Conceptual Model
Comparisons between predicted and measured water
contents and outflow from the lysimeter are shown in
Figure 3. These predictions were made with the laboratorymeasured hydraulic properties and with the properties
obtained via inversion. Cumulative outflow from the
lysimeter predicted with the inverted parameters matches
the measured outflow reasonably well, although the
predicted outflow is slightly lower than the measured
outflow towards the end of the record. In contrast,
the prediction using laboratory-measured parameters
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25
than actually occurs in the field.
The water contents predicted using the laboratorymeasured hydraulic properties as input also provide a clue
that the conceptual model has deficiencies. The predicted
rise in water content after dosing lags behind the rise
observed in the field. After the rise, however, the predicted
water content remains essentially constant in the same
manner that occurs in the field. That is, the initial transient
behavior is predicted more accurately using the inverted
parameters, whereas the equilibrium condition is predicted
more accurately with the laboratory-measured parameters.
Inversion consists of running a model
“in reverse” to find the set of input
parameters that results in the prediction that most closely resembles the
state or behavior observed in the field.
Figure 4. Predicted MSW saturation adjacent to leachate recirculation trenches (blue rectangles) for saturated hydraulic conductivities of 10-5, 10-6, and 10-7 m/s.
underestimates the measured outflow appreciably. The
water content predictions are also more accurate when the
inverted hydraulic properties are used as input. The rapid
rise in water content after dosing is captured, as is the
subsequent leveling off, when the inverted parameters are
used as input.
The comparison of predicted and measured water
contents illustrates that the conceptual model of the
lysimeter has deficiencies. The field data indicate that the
water content remains relatively constant after dosing,
whereas drain down is predicted after dosing when the
inverted parameters are used as input. Apparently, the high
saturated hydraulic conductivity used to provide a good
match with the outflow curves and the rapid rise in water
content also predicts that the MSW will drain more readily
26
This inconsistency suggests that flow in the MSW
could be better represented by a two-component flow
field consisting of preferential flow paths that transmit
leachate in and out of the lysimeter rapidly and a matrix
of less conductive MSW that retains water after dosing.
The reasonable agreement between the equilibrium water
contents observed in the field and the water contents
predicted using the laboratory-measured hydraulic
properties suggests that the matrix was characterized
reasonably well by the laboratory tests on the shredded
MSW. However, even though large-scale tests were
conducted, the tests probably were too small to incorporate
preferential flow paths similar to those present in the
lysimeter. The reasonable agreement between the inverted
and laboratory-measured WRC parameters also indicates
that the laboratory tests provided a reasonable assessment
of conditions within the matrix.
Practical Implications
An example of the practical significance of the improved
parameterization obtained from inversion is illustrated
in Figure 4, which shows predictions of MSW saturation
surrounding four leachate injection trenches (blue boxes).
The predictions were made with HYDRUS using WRC
parameters obtained from inversion and three different
saturated hydraulic conductivities ranging from 10-5
m/s (comparable to saturated hydraulic conductivities
obtained by inversion) to 10-7 m/s (comparable to saturated
hydraulic conductivities measured in the laboratory).
Very different distributions of saturation are predicted
as the saturated hydraulic conductivity is varied. The MSW
with high saturated hydraulic conductivity is approximately
60 percent saturated by leachate injection, whereas the
Engineers need to
scrutinize predictions
carefully, and avoid
being caught in
the “model is reality”
trap.
predictions with lower saturated
hydraulic conductivity indicate the
MSW is 80-90 percent saturated.
If the recirculation trenches were
operated based on findings from
predictions based on the laboratorymeasured properties, the injection
rate might be too low to achieve
moisture conditions that are optimal
for decomposition of the MSW.
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These findings, and others,
illustrate that numerical models
can be powerful tools for prediction
in geoenvironmental engineering.
However, they may also produce
predictions that appear realistic but
are also unreasonable. Engineers
need to scrutinize predictions
carefully, and avoid being caught in
the “model is reality” trap. Educators
also need to train students about the
pitfalls of model predictions, and the
importance of “reality checks” and
ground-truthing with field data.
Most predictions are very sensitive
to how the model is conceptualized
and parameterized. If field data
are available, inversion can be
used as a powerful tool to improve
parameterization and to identify
potential deficiencies in conceptual
models. While inversion may have
been cumbersome historically,
many commercial software packages
now include automated inversion
routines. Engineers are encouraged
to explore using inversion to
improve the quality and reliability of
predictions.
Craig H. Benson, Ph.D., P.E., D.GE,
F.ASCE, is Wisconsin Distinguished
Professor and Chair of Geological
Made in the U.S.A.
PRESTO
AP-6146
30 years of innovation
Engineering at the University of
Wisconsin-Madison in Madison, WI.
His research interests are primarily
in designing, analyzing, and testing
geotechnical components of landfills
and other waste containment structures.
Craig can be contacted at chbenson@
wisc.edu
GLOBAL LEADER • GLOBAL PARTNER
Ronald J. Breitmeyer is a Ph.D.
candidate and graduate research
assistant in Geological Engineering at
the University of Wisconsin-Madison in
Madison, WI. He can be contacted at
[email protected]
27
Using Numerical Analysis in
Geotechnical Engineering Practice
By Lidija Zdravković, Ph.D., DIC and David M. Potts, Ph.D., DSc, FREng
N
umerical analysis, in terms of finite element or finite
difference methods, has become a popular calculation
tool in geotechnical design. It is particularly necessary to
apply numerical analysis in cases of complex geotechnical
structures and ground conditions, where classical methods
of analysis (linear elastic, limit equilibrium, stress field, and
limit analysis methods) cannot produce adequate solutions.
A number of specialist geotechnical software packages
are currently available commercially and in research. They
usually differ in the level of sophistication and in the way
in which constitutive models, boundary conditions, and
numerical solvers are implemented, as there is currently no
internationally agreed guidance on best practice for such
implementations. Consequently, it is not unusual to obtain
different answers to the same problem from different
software. For a successful analysis, it is also important for
the user to understand how the applied software works and
what might be going on in the computer “black box.”
If no other model input parameter is required, this
implies that the model is assumed to be associated,
meaning that the direction of plastic strains can be
determined from the model’s yield surface, which is defined
by c’ and φ’. It further implies that the angle of dilation in
the soil, ψ, is equal to φ’.
As a result, the model will produce excessive dilative
(expansive) strains in the soil. In addition, it will not be
possible with such analysis to determine the ultimate load
for volumetrically confined problems, such as an undrained
bearing capacity of a shallow foundation, or a capacity of
a pile foundation. This outcome is illustrated in Figure 1,
where drained load-displacement curves for a vertically
loaded pile 1.0 m in diameter and 20 m long are presented,
in a soil with c’ = 0 and φ’ = 25°.
The linear elastic-plastic Mohr-Coulomb model, one of
the simplest geotechnical constitutive models, provides a
good example of the some of the problems and solutions
involved. This model is a feature of most geotechnical
software, but users still make mistakes due to their lack
of understanding of the model. Analyses described in the
following sections were performed using the Imperial
College finite element program ICFEP.
Ultimate Limit States
A common design requirement for geotechnical
structures is the bearing capacity of foundations, both
shallow and deep. If the Mohr-Coulomb model is applied
in such analysis, the following model input parameters are
required:
• for elastic soil behaviour: soil stiffness in terms of
the Young’s modulus, E, and Poisson’s ratio, ν;
and
• for plastic (failure) behaviour: the soil cohesion,
c’, and the angle of shearing resistance, φ’.
28
For the case of an associated Mohr-Coulomb model,
the load-displacement curve never reaches a limit load,
no matter how far the pile is pushed into the ground.
Faced with such a prediction, the user may then arbitrarily
determine the limit load, for example, as the magnitude
of the vertical force when the displacement is equal to
10 percent of the pile diameter (0.1 m in this case). This
arbitrary decision is non-conservative, as soil dilation is
normally smaller than φ’.
VisualFEA - Geotechnical Finite Element Analysis Program
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Capability of looking inside the solution
Failure envelope
Yield surface
Data probing
Stress
sampling
Stress
path
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Variety of applications
Seepage analysis
(3D rendering of the phreatic surface)
Slope stability analysis
(coupled with seepage analysis)
Website : www.visualfea.com
Email : [email protected]
Frame analysis
(with specified sections)
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If the software has the flexibility for the user to input
the angle of dilation to be smaller than φ’, then for any
value of 0 < ψ < φ’, the analysis will still not produce an
ultimate limit load, as shown in Figure 1 for the case of ψ =
⅔ φ’. The user will again have to make an arbitrary decision
on the magnitude of the limit load. Only if ψ = 0 will the
load-displacement curve reach an ultimate load, as shown
in Figure 1. Such an ultimate load will be conservative, as
most soils normally dilate to some extent, but the outcome
will at least be the theoretically correct ultimate load (for ψ
= 0), without any arbitrary decision from the user.
Serviceability Limit States
Apart from failure conditions, it is also necessary to
design geotechnical structures for working conditions,
where ground deformations are limited so that the new
and the existing structures and services can function
adequately. This is particularly important for designs in
urban environments, where, for example, deep excavations,
tunnels, and new foundations have to be constructed
next to, or underneath, existing structures and services.
What becomes important for design is the determination
of ground movements imposed by new construction and
whether they can cause any damage to existing buildings.
Figure 2 shows the layout of two London Underground
(LU) tunnels as they pass into St. James’s park in London,
UK. The 30-m-deep westbound and the 20-m-deep
eastbound tunnels, of 3 km total length, are part of the
extension of the LU Jubilee Line, and were constructed
between 1994 and 1996. The figure shows that at this
location the tunnels pass directly underneath the Treasury
building, with several other buildings (shaded areas) in
the direct vicinity. To the left of the Treasury building, the
tunnels pass underneath the greenfield area of St. James’s
park, which was heavily instrumented for monitoring of
both ground movements and stress changes in the soil due
to the tunnels’ advancement.
Both tunnels were excavated undrained in the London
Clay formation. The measured settlement trough above
the westbound tunnel at St. James’s park, which was
constructed first, is used to demonstrate the necessity for
advancing the capabilities of a constitutive model in order
to obtain reasonable predictions of tunnel-induced ground
movements.
Since in this type of boundary value problem the
deformations are small, the pre-failure characteristics of
30
Figure 2. Layout of Jubilee Line tunnels at St. James’s park.
the model dominate the predicted behaviour. If a simple,
linear elastic-plastic Mohr-Coulomb model is applied,
such as used in the pile loading example, the predicted
surface settlement trough is shown in Figure 3. In this case,
the pre-failure behaviour of the Mohr-Coulomb model
is characterised by an isotropic, linear elastic Young’s
modulus, which increases linearly with depth, producing
the surface settlement trough which does not resemble the
measurements.
A possible advancement in modelling the pre-failure
behaviour of the soil could be the introduction of
anisotropic linear elastic stiffness characteristics. In the
case of London Clay, which is a heavily overconsolidated
material, the stiffness in the horizontal direction is
much higher than that in the vertical direction. If these
characteristics are introduced in the pre-failure behaviour of
the Mohr-Coulomb model, with both directional stiffnesses
increasing linearly with depth, the predicted surface
settlement trough (Figure 3) is slightly better than that of
the isotropic linear elastic pre-failure model, but is still too
shallow and wide compared to the measurements.
Advancements in laboratory testing over the past 20
years, in particular the introduction of local instrumentation on triaxial samples, have shown that soil stiffness is
not constant, i.e. linear elastic. Rather, it is highly nonlinear,
Pre-Failure Model
Figure 3. Predicted and measure surface settlement trough above the
westbound tunnel.
Distance from centre line (m)
Settlement (mm)
It is not unusual to obtain different
answers to the same problem from
different software.
0
centre line
25
50
isotropic linear elastic
anisotropic linear elastic
nonlinear elastic
20
field data
varying from a high value at very small strains to a small
value at intermediate to large strains. Soil stiffness also depends on the stress level in the soil such that it increases
with an increasing stress.
Apart from failure conditions, it is
also necessary to design geotechnical
structures for working conditions,
where ground deformations are limited
so that the new and the existing
structures and services can function
adequately.
An example of how the shear stiffness, G, of London
Clay, normalised by the mean effective stress p’, varies with
strain level in both triaxial compression and extension is
shown in Figure 4. The figure clearly shows that stiffness
degradation is highly nonlinear and therefore must be
modelled using a nonlinear elastic model. If such a model
is introduced to represent the pre-failure behaviour of the
Mohr-Coulomb model and applied in the analysis of the
westbound tunnel construction at St. James’s park, it is clear
32
Ge o-Strata l geoins t it ut e. or g
Figure 4. Shear stiffness degradation of London clay.
Gsec
p′
Shear Stiffness
600
nonlinear elastic
400
CAU compression test
200
0
0.001
CAU extension test
0.01 0.1
1.0
Shear strain (%)
from Figure 3 that such modelling significantly improves
the prediction of the surface settlement trough above the
tunnel.
Pitfalls of Simple Models
The complexity of the constitutive model required in
a finite element analysis depends on the nature of the
boundary value problem to be analysed. The simple, but
extensively used, Mohr-Coulomb model has shortcomings.
For ultimate limit state problems such as bearing capacity
in soil, the Mohr-Coulomb model
produces excessive dilative strains
and cannot provide an ultimate load
for volumetrically confined problems
when dilation in the model is greater
than zero.
For serviceability limit state
problems where ground movements
are limited, deformations do
not realistically match observed
behaviour if the Mohr-Coulomb
model is characterised by an
isotropic, linear elastic Young’s
modulus. Where these limitations
are unacceptable, such as for
more complicated structures and
ground conditions, more advanced
constitutive models may be needed.
These models may have to deal
with variable soil permeability, soil
structure, creep, unsaturated soil
behaviour, or strength anisotropy. The
classes of models that can simulate
these aspects of soil behaviour are
known as the kinematic surface and
bounding surface plasticity models.
Additional pitfalls can occur
when selecting appropriate
boundary conditions for a particular
problem. The standard static and
hydraulic boundary conditions that
are commonly available may be
inadequate and misleading, especially
if the problem has to consider
infiltration, evapo-transpiration, or
dynamic loading conditions.
Lidija Zdravković, Ph.D., DIC,
is an associate professor at Imperial
College London. Her main research
interests are in the field of numerical
geotechnical analysis, involving both
software development and engineering
applications. She has co-authored two
books on geotechnical finite element
analysis with David Potts. She can be
reached at l.zdravkovic@imperial.
ac.uk
David M. Potts, Ph.D., DSc, FREng,
is a professor and the deputy head of the
Department of Civil and Environmental
Engineering at Imperial College
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He is the author of the geotechnical
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[email protected]
Geo-Strata is interested in
hearing from you. Please send
your comments on this article
to [email protected].
33
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Advancing the Practice of
Levee Analysis
By Scott Anderson, P.E., M.ASCE
E
xperts predict that an extreme weather event in
Sacramento’s Natomas Basin has the potential to produce
flood waters in excess of 20 ft deep, which would affect
more than 53,000 acres and more than 70,000 people.
The U.S. Army Corps of Engineers (USACE) Sacramento
District has stated that the 42 miles of levees that contain
the Natomas Basin do not provide a 100-year level of
flood protection. Subsequently, the Federal Emergency
Management Agency (FEMA) new flood zone maps,
effective in December 2008, led to flood insurance
requirements for existing residents and a de-facto
moratorium on issuance of new building permits in the
area.
The goal of the NLIP is to provide 100year protection as quickly as possible
and 200-year protection for all levees
by 2013.
In response, the Sacramento Area Flood Control Agency
(SAFCA) initiated the Natomas Levee Improvement
Program (NLIP), a $618 million, seven-year project to
expedite repair and rehabilitation of the entire levee system.
The goal of the NLIP is to provide 100-year protection as
quickly as possible (with a target of 50 percent of the levees
improved by 2011), and 200-year protection for all levees
by 2013.
SAFCA is looking to a team of expert geo-professionals
to develop an understanding of the complexities of
this unique levee system and engineer the necessary
improvements. In the wake of Hurricane Katrina, the
standard of care for the nation’s levees has been redefined
since 2005, as have the methodologies, tools, and
techniques for analysis and design.
The project provides a unique opportunity to further
advance the state of the geotechnical practice in terms of
levee analysis and design. Three years into the program, the
engineering team has performed side-by-side comparisons
of the most advanced groundwater and slope stability
36
modeling and analysis tools for both short and longterm scenarios, demonstrated innovative probabilistic
vulnerability studies to quantify relative reliability of
embankments, and developed ever more accurate and
efficient answers to highly complex questions.
Sacramento River Options
The NLIP site footprint includes 700 parcels of land
around the perimeter of the basin. The flood protection
system is composed of several major components:
• Sacramento River East Levee (approx. 18 miles),
• Natomas Cross Canal South Levee
(approx. five miles),
• American River North Levee (approx. two miles), and
• Natomas East Main Drainage Canal West Levee
(approx. 13 miles) with the Pleasant Grove Creek
Canal West Levee (approx. three miles).
The Sacramento River is the main
drainage feature of the northern
part of the region, flowing generally
southward from the Klamath
Mountains to its discharge point into
Suisun Bay in the San Francisco Bay
Area.
For the Sacramento River portion of the project,
the geotechnical evaluation team opted to run three
slope stability solutions in parallel to see if results
came within the acceptable algorithmic differentials. As
background, engineers found that the available slope
stability analysis tools used to assess the New Orleans
levees provided inconsistent answers when assessing the
same problem. The slope stability tools selected included
the industry benchmark system, UTEXAS4 developed by
point into Suisun Bay in the San
Francisco Bay Area. In the project area,
the river is confined by man-made
levees that were generally constructed
on Holocene-age alluvial and fluvial
sediments deposited by the current
and historical Sacramento and San
Joaquin Rivers and their tributaries.
Pleistocene deposits underlie the
Holocene deposits.
The geomorphology of the region
does not lend itself to regular spaced
borings, but required a detailed
exploration program that incorporated
helicopter electromagnetic surveys
(HEM) and electrical resistivity testing
to assist in identifying crevasse splay
deposits and other anomalies that
could lead to seepage and stability
issues. In addition, piezocone
penetrometer (CPT) and vane shear
(VST) testing was used to evaluate
areas of soft silt and clay.
Using the field data, the engineers
first input the various parameters
into the three slope stability analysis
programs to evaluate the influence of
each levee cross section’s soil shear
strengths, pore water pressures, and
loading from proposed remediation
strategies on the factor of safety against
failure. While not as graphically
advanced or presentation friendly as
compared to more recently developed
solutions, the UTEXAS4 slope stability
program uses limit equilibrium
procedures to calculate a factor of
safety against failure. Similar to the
Figure 1. Outline of the Natomas Basin levees surrounding a portion of Sacramento,
UTEXAS4 solution, SVSlope provides
CA and areas to the north.
advanced analysis of slope stability
that can incorporate probabilistic
methods including Monte Carlo,
Dr. Stephen Wright at the University of Texas, SLOPE/W
Latin
Hypercube,
and
Alternate Point Estimation Method
by Geo-Slope International, Ltd., and the newer SVSlope®
sampling, as well as the industry-accepted Duncan, Wright,
limit equilibrium slope stability solution from SoilVision
and Wong rapid draw-down methodology. SLOPE/W is also
Systems, Ltd.
capable of sensitivity and probabilistic analysis.
One River, Many Variables
The geotechnical team had to deal with a number of
complexities. The Sacramento River is the main drainage
feature of the northern part of the region, flowing generally
southward from the Klamath Mountains to its discharge
The greatest analytical edge gained from recent software
is in seepage analysis. Traditionally, engineers have relied
on programs like Seep2D to compute seepage on profile
models such as for earthen dam and levee cross sections.
Many new industry professionals are not familiar with
the command words and the formatting required by the
37
older DOS-based programs, which can make the overall
process very laborious. For this effort, the engineering team
also looked to SVFlux, a 1D, 2D, and 3D finite element
groundwater modeling solution, and SEEP/W to provide
the input to the slope stability programs. Both the SVFlux
and the SEEP/W software solutions allow for import
of information generated from their respective seepage
programs into the slope stability programs.
One of the more useful features from
the older DOS programs is the flexibility to select data from the seepage
analysis results for use by importing
pore pressures from specific layers and
using piezometric lines for others.
Figure 2. Example slurry trench stability analysis using SVSlope,
one of three slope stability programs used.
One of the more useful features from the older DOS
programs is the flexibility to select data from the seepage
analysis results for use by importing pore pressures from
specific layers and using piezometric lines for others. This
feature from the older DOS programs was also found in the
SVFlux solution. Although not explicitly permitted by the
design parameters of several levee regulatory agencies, both
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38
SVFlux and SEEP/W can provide transient analysis, which
can be used to evaluate the change in factor of safety with
changes in water level and evaluate the progression of the
wetting front through the levee cross section.
Probabilistic methods are also available in the seepage
software, which run several analyses while varying the water
levels and variables such as the hydraulic conductivity and
anisotropy to see the change in gradient or uplift pressure.
The automation of these analyses greatly improves the
engineer’s efficiency, but the efficiencies gained should not
be squandered. The time savings should allow an engineer
more time to think about the implications of the results of
the analyses and thereby develop a better understanding of
the significance of the results.
Thinking About Probability
The state of the practice in levee analysis and design
has evolved considerably in the last four years. A critical
advance in this evolution is the ability to perform
probabilistic analysis, which develops a probability
distribution for a specific material property to see variations
in behavior due to the distribution of material properties.
UTEXAS4 does not explicitly perform this type of analysis as
of yet, however SLOPE/W and SVSlope have this capability.
A critical advance in the evolution of
levee analysis and design is the ability
to perform probabilistic analysis, which
develops a probability distribution
for a specific material property to
see variations in behavior due to the
distribution of material properties.
SLOPE/W solves for a deterministic failure surface and
then performs a probabilistic analysis on that surface.
SVSlope, on the other hand, can vary the failure surface as a
function of material properties on the slip surface, e.g., the
probabilistic analysis results in changes to the slip surface
location. Currently, the probabilistic analysis evaluations
are made for internal use, calibrating on probability of
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failure. Regulatory agencies have guidance on the use of risk
and reliability analysis of levees; however, the agencies seem
to be reluctant to use them due to a lack of calibration of,
and thus acceptance by the general engineering community,
to the “probability of failure” concept. Most engineers
have been indoctrinated using the factor of safety and have
developed “internal” calibrations. They have a “feel” for
what a 1.4 factor of safety is like. They don’t have a “feel”
for an annualized failure rate of 1/30.
NLIP Update
Using these analysis techniques, the geotechnical design
team has been able to contribute to overall levee repair
designs that are also moving through the construction
phase. The first of the NLIP construction projects began in
2007, with additional work in 2008. Major improvements
began in spring 2009, and additional phases have been
awarded. In August 2009, groundbreaking took place on the
$22 million Natomas Cross Canal Phase 2 and Sacramento
River East Levee Phase 1 (Reach 1) improvements and a
second $21 million Sacramento River East Levee Phase 1B
(Reach 2-4B) project. This work is slated to be completed
in 2010. Sacramento River Phases 2 and 3 are expected
to begin construction in 2010. The construction on the
improvements is scheduled for a completion of around
2015; however the bulk of the analysis is anticipated to be
finished by early 2010.
Of course, no matter how good the software is in
performing the analysis, the most critical step is the wise
selection of parameters that go into the analysis software.
With today’s advanced solutions, engineers can readily see
the impact of varying those parameters on critical levee
structures during ordinary and extreme conditions. It is
imperative that no matter how advanced the software is, it
cannot and should not replace sound engineering judgment
and an appreciation of the physics of the problem.
Scott Anderson, P.E., M.ASCE, is a principal engineer,
Numerical Modeling Group Director, with Kleinfelder, Inc. in
Sacramento, CA. He specializes in numerical modeling and
advanced laboratory testing, and serves on the Computational
Geotechnics Committee of the Geo-Institute. Scott can be reached
at [email protected]
Geo-Strata is interested in hearing from you. Please send
your comments on this article to [email protected].
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CO2 Sequestration: Fractures Are
Enabling Clean Energy Options
By Joseph Morris, Ph.D., and Laura Pyrak-Nolte, Ph.D.
Figure 1. The amine CO2 removal facilities at Krechba. (Image courtesy of ISG CO2 JIP)
F
or most people, the idea that rock fractures can “go
green” might seem a bit far-fetched. However, large-scale
carbon capture and sequestration (CCS) projects involving
annual injections of millions of tons of CO2 into geologic
formations deep underground have emerged as a method to
enable substantial reductions in greenhouse gas emissions.
Subsurface injection projects will need to be employed
on a grand scale if geological carbon sequestration is to
affect significant reductions in greenhouse gases in the
atmosphere. These projects will likely require multiple wells
into which millions of tons of CO2 will be injected over 30
years or more. For storage in saline formations, this is likely
to create large and increasing pressure perturbations that
will grow over the duration of the injection project.
Each project will involve distinct geological features and
many will include geologic targets containing preexisting
fractures. In addition, the large rate and volume of injection
may induce pressure perturbations within the formation
that can activate existing fractures and faults, or create new
fractures within the reservoir or caprock. Consequently,
understanding the role of fractures in controlling flow
through rock masses is key in predicting the performance of
industrial-scale CO2 geological storage.
42
In Salah Gas
The In Salah Gas (ISG) CO2 Storage project in Algeria
is one example of what will ultimately be many projects
needed to achieve significant reductions in greenhouse
gas emissions. The ISG injects approximately one million
tons of CO2 annually into a deep saline formation. The
response of the formation illustrates how fractures act to
amplify the connection between geochemical and hydromechanical processes in subsurface reservoirs. Though other
injection projects will involve distinct geological formations
and structural features from those of the In Salah project,
many geologic targets will contain pre-existing fractures
and faults. In addition, potential pressure perturbations
within the formations from the large rates and volumes of
injection can activate existing fractures and faults, and/or
create new fractures within the reservoir or caprock.
In Salah Gas has two fundamental goals: (1) 25-30
years of 9 billion cubic ft/year of natural gas production
from eight fields in the Algerian Central Sahara, and (2)
successful minimization of the associated environmental
impact by capture and subsurface isolation of excess CO2
extracted from production streams. The gas produced from
these fields is too rich in CO2 for export to Europe and is
consequently purified before being piped out of the field
area. Separated CO2 is normally vented from gas plants,
Amine CO2 Removal
Figure 2. CO2 injection scenario employed at
Krechba. If this image was to scale, the 20-m thick
reservoir would appear as a single, almost flat, line.
PROCESSING FACILITIES

5 GAS
PRODUCTION
WELLS
3 CO2 
INJECTION
WELLS
GAS
WATER
but at In Salah, the separated CO2 is geologically stored in
a deep saline formation that has been characterized to oil
and gas standards. Since 2004, the ISG facility at Krechba,
has stored the CO2 in a deep saline formation, down-dip
from the producing gas field (Figure 2).
Hydro-Mechanical Effects
The Krechba reservoir is an approximately 20-m-thick
sandstone unit at a depth of 1800 m, situated 150 km
from the nearest settlement, In Salah. Predicting the hydromechanical response of the reservoir is proving to be
important in understanding the ultimate fate of the injected
CO2. Although there is no evidence of faulting through the
overlying caprock, there are faults and extensive fracture
networks within the reservoir itself that potentially control
the mobility of the CO2. Figure 3 shows the potential faults
identified within the reservoir and some of the fractures
identified from FMI (Formation MicroImager) logs. Recent
hydro-mechanical analysis has demonstrated that features
shown on the fault map are consistent with observation
of surface uplift and detection of CO2 by monitoring wells
(Figure 4).
Image adapted from ISG CO2 JIP.
1
Cretaceous Sandstone
& Mudstones
~ 900 metres thick (Regional Aquifer)
2 Carboniferous Mudstones
~ 950 metres thick
3 Carboniferous
Reservoir
~ 20 metres thick
Additional analysis was performed to investigate deformation of the fracture network within the reservoir. Fractures that fail in shear are expected to develop enhanced
43
Geochemical Effects
Seismic Data
Figure 3. Seismic data indicates
potential faults in the reservoir, but
not the caprock (at top).
Indications of predominant fracture orientations are shown on FMI
logs (at bottom).
(Data courtesy
of ISG CO2 JIP).
No potential faults
In addition to hydro-mechanical effects, injecting
CO2 into a subsurface reservoir can initiate a complex
set of geochemical reactions that involve interactions
between aqueous solutions and minerals in the host rock
(Figure 6). Consequently, a complete assessment of a
given reservoir’s suitability for CO2 sequestration requires
geochemical analysis in addition to geomechanical analysis.
For example, geochemical reactions can lead to mineral
precipitation in voids and fractures or dissolution of the
host rock.
The hydro-mechanical behavior of fractures can be
significantly affected by such geochemical interactions.
For example, while dissolution along fracture surfaces may
initially enlarge the apertures in a fracture, the subsequent
changes in the stress distribution along the fracture plane
can lead to closure or reductions in apertures that in
turn reduce fluid flow through the fracture and fracture
networks.
Potential faults
permeability, resulting in modification of the CO2 plume.
Figure 5 shows the response of the combined fracture and
fault network to a hypothetical pore pressure increase under
different in-situ stress conditions. This calculation considers
the poroelastic response of the fractured rock mass and includes the redistribution of stresses through the combined
fracture-fault network. The black regions highlight sections
of the faults and fracture network that will fail and potentially enhance permeability within the reservoir. In particular, there are two fault sections near the injection site that
are predicted to be conduits for fast flow in this scenario.
Uncertainty in the in-situ stress orientation, fracture
strike variability, and fault strike uncertainty/variability
was a key issue that was also explored. For example, it is an
unfortunate fact that the in-situ stress state is only poorly
characterized for most fields. Consequently, the precise
level of induced shear stress on fault segments will be
equally uncertain. For the fracture network at In Salah, even
though the in-situ stress was well characterized, we found
the hydromechanical response was very sensitive to the
orientation of the in situ stress.
44
Understanding the role of fractures in
controlling flow through rock masses
is key in predicting the performance of
industrial-scale CO2 geological storage.
Recent laboratory experiments have shown that
preferential dissolution at points of contact between
surfaces can lead to large displacements that rapidly
reduce fracture apertures. The amount and rate of closure
of a fracture subjected to dissolution depends on the
spatial distribution of apertures within the fracture which
controls the hydrodynamic behavior and also on the spatial
distribution of local chemical reaction rates. On the other
hand, recent research performed at Purdue University has
demonstrated that mineral precipitation within a fracture
can lead to blocking or plugging of the fracture, thereby
reducing storage capacity of a reservoir or potentially acting
as a mineral seal to trap CO2 in the subsurface.
The Future of CO2 Sequestration
Understanding of CO2 sequestration performance is
moving forward on multiple fronts. In the laboratory,
detailed experiments are providing insight into the linkage
between geochemical and geomechanical processes at small
scales. In the field, full-scale deployment at projects such
as the In Salah Gas Project are giving indications of how
fracture networks respond to enhance both injectivity and
storage capacity.
8
Displacement
Rate
Remote Sensing Tools
Figure 4. Geomechanical analysis of faults
showing expected fast flow paths (blue) and
flow barriers (red). InSAR data (Courtesy of ISG
CO2 JIP) is a remote sensing tool to monitor
subsurface volume change (red = uplift; blue =
subsidence).
7
6
5
N29˚5΄
4
3
2
1
0
mm/year
-1
-2
N
F12
predicted to be conducting
F9
predicted to be stable:
Flow barrier south of KB-502
Impermeable
Permeable
SHmax
Discrete Element Simulations
Figure 5. Discrete Element Simulations using the Livermore Distinct Element code for eXport explore sensitivity of
pore-pressure induced fracture network shear failure to uncertainty in in-situ stress orientation.
Discrete Element Simulations


N
N
15˚


15˚
SHmax
SHmax
0˚

0˚

SHmax

SHmax
15˚
SHmax

Figure 5. Discrete Element Simulations using the Livermore Distinct Element code for eXport explore sensitivity of
pore-pressure induced fracture network shear failure to uncertainty in in-situ stress orientation.
SHmax
0.6
10
MPa
0.0
0
MPa
0.6
0.0
15˚
10
MPa
Fracture Network Fails in Shear
0
MPa
Fracture N
45
Chemical and Hydromechanical
Processes
Figure 6. Within the geologic sequestration target, chemical and
hydromechanical processes are coupled (Johnson et al., 2003).
Geo-Strata
Coming in
March/April 2010:
Levees At Risk
• Is Doing Levee Work Worth
Destroying Your Firm?
• Making Levees Safer by
Hedging Our Bets
• A Decade of Delivery: The
Geo-Strata Story
• What’s In Your Levee?
• Fast-Track Repairs of Critical
Levee Erosion Sites
• Characterizing the Seismic Threat
to California’s Water Supply
Joseph Morris, Ph.D., is a research scientist at the Lawrence
Livermore National Laboratory in Livermore, CA, where he
manages several CO2 sequestration-related research projects. He
has also developed multiple software tools for simulating coupled
hydromechanical effects in fracture networks. He can be reached
at [email protected]
Laura Pyrak-Nolte, Ph.D., is professor of physics at Purdue
University in West Lafayette, IN where she studies the effects of
fractures on seismic and acoustic wave propagation, the geometry
of single fractures and fracture networks, and fluid flow through
fractures and fracture networks. She can be reached at ljpn@
physics.purdue.edu
46
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California Central Valley Urban
Levees
• So You Live Behind a Levee!
And, introducing a new feature:
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GeoCurmudgeon
The World Is Run By Those Who Show Up
By John Bachner
Legal professionals must be important; a lot of them
charge $300-$350 an hour and more. And by applying that
metric, one would have to conclude that geoprofessionals
are far less important, because many of them charge
so much less. But that conclusion would be wrong:
Geoprofessionals are vital to preserving humankind’s
sustainability on Earth, whereas attorneys…hmmmm: What
do they do that makes their fees acceptable?
In fact, it’s not so much what attorneys do as what
people perceive they do. And as we all know, what people
perceive to be their reality is their reality. So why is it
that people perceive what attorneys do as being so much
more valuable than what geoprofessionals do? Because
attorneys know, as you should, too, that the world is run
by those who show up…and you cannot show up unless
others notice you’re there. Sure, preserving our species is
important. But look what happens when no one knows
you’re doing it.
Geoprofessionals have offered various explanations
for not showing up, telling me and others that they
cannot handle confrontation and the risk of rejection;
that they don’t like compromise; that they’re not “wired”
for public display; and so on. And we can also look at the
way geoprofessionals are educated, which – for the most
part – involves an exclusive focus on technical issues, with
little regard for history, English, art, public speaking, etc.…
the educational staples of most lawyers. (I’ve been told
it’s possible to go through four years of an engineering or
science program without saying a single word in class other
than “Present.”)
“We need to change the way geoprofessionals are
educated,” a number of senior practitioners say. But not as
many agree that almost an additional year of study is called
for. And even fewer insist that geoprofessionals have more
background in the humanities. So what does that mean?
In truth, it means nothing at all.
Well over 1,000 people have now gone through
ASFE’s Fundamentals of Professional Practice course for
geoprofessional firms’ rising stars; six months of remote
study followed by a course-concluding 2½-day seminar.
Speaking before small groups is an important element of
the seminar and, for many of the younger participants,
it’s the first public-speaking experience of their careers. A
lot of them are not very good at it. One such participant –
let’s call him Steve – was particularly upset with his poor
public-speaking performance. He asked me what he could
do to improve and I suggested that he get involved in
Toastmasters International. He did and, about seven years
later, I was in his “neck of the woods” and gave him a call.
“Joining Toastmasters was the best thing I ever did,” he told
me. “I learned how to get over my public-speaking fears and
inhibitions, and now I really enjoy it. In fact, I do it every
chance I get.” And the more he does it, the more chances he
gets to do it.
How important is that? It’s huge, frankly, because
speaking confidently in public is how people know you’re
there, showing up. It’s what leaders do. Do you want
society to think you’re important? Speak up! Do you want
to earn the kind of fees that important people command?
Speak up! And be sure to do it via the organizations that
comprise the public. Does that mean geoprofessional
groups, like G-I? As confidence-building starts, sure; they
comprise friendly enclaves of like-minded individuals
whose compatible backgrounds help novice speakers feel
comfortable. But graduate as quickly as you can to public
groups whose members’ common interest is something
other than the same technological endeavors, so you can
impress upon folks other than geoprofessionals what
it is you and your cohorts really do. And that’s pretty
impressive stuff. After all, you help make human progress
possible and, more and more, you are doing so while
helping society preserve Earth’s physical resources for use
by future generations. Should that make you feel good
about yourself? Absolutely. Should that give you the
wherewithal to stand up in front of people and address
them a confident, persuasive manner? It’ll help, but you’ll
need more.
49
First and foremost, you’ll need
to stop believing in flimsy excuses.
Being able to speak well in public
is not a genetic endowment. It is
an acquired skill you hone through
practice. (If Steve can do it, trust me:
You can do it.) And when you gain
self-confidence as a speaker and
combine it with your self-confidence
as custodian of our planet, you have
something powerful to offer.
How long will it take before
people start to realize that
geoprofessionals are not only
important, but even more important
than lawyers? I have no clue. But I
do know that, unless you and your
peers are willing to invest the time
and energy required to be able to
speak confidently in public, it’s never
going to happen. Sure, lawyers may
have an advantage by virtue of their
education and by virtue of what some
may say is a natural proclivity for
humanistic involvement. But lawyers
are not custodians of the planet. You
are. And while many attorneys may
be passionate about our environment
and preserving it, passion doesn’t
get the job done. Nor does a law
degree or passing a bar exam. But
people aren’t going to know that as
long as geoprofessionals stay mum.
And while you may agree with those
sentiments, nodding one’s head does
nothing to improve the situation.
Geoprofessionals need to show up.
That means you. You need to believe
that what you do is important,
because it is. And you need to believe
that, as a result, you are important,
because you are. And then you need
to get out of your comfort zone and
show up, then let others know you’re
there. You can do that.
Speak up.
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50
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ISO 9001:2008
registered
John P. Bachner is the executive
vice president of ASFE, a not-for-profit
association that provides programs,
services, and materials that its members
– geoprofessional firms – apply to
achieve excellence in their business and
professional practices. Contact John at
[email protected]
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compete at the Geo-Challenge at the
annual Congress. Please contribute
when you renew your membership,
or donate online by logging in at
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and Make Contributions.”
GeoFlorida 2010
February 20-24, 2010
Palm Beach County
Convention Center
West Palm Beach, Florida
www.geocongress.org
Daily Registration Rates are
Available.
Uncover new developments in
geotechnical engineering analysis,
modeling, and design. Be a part of
52
ence the Terzaghi lecture and doze
ns of technical presentations cover
ing all areas of the profession. Toas
t the G-I 2010 Hero, J. Michael Duncan,
at the Hero and Awards Luncheon. Mee
t ASCE authors Clyde Baker, Vau
ghan Griffiths and Gordon Fenton a
t the ASCE Bookstore. Browse the Ex
hibit Hall. Take the special Techni
calTour,plusmuchmore. TheGeo-Ins
titute Board Need
s
You Here is your opportunity
to b
ecome involved in the leadership of
the Geo-Institute. The G-I’s Nomi
nations and Elections Committee is so
liciting nominations for one seat on t
he Board of Governors beginning
in October 2010. As immediate GI Past President, Jean-Louis Briaud
stated, “By being on the Board, I met
many more G-I members than I would
have had a chance to otherwis
e. It gave me an opportunity to hel
p the profession continue to improv
e. Plus, it taught me more about how t
o reach consensus on tough issues, ab
out how to find win-win solutions
during discussions, how to keep the
big picture in mind at all times,
and how to put the members first.” P
ast President Steve Wright
s
tates: “I rekindled old friendships and
made many new friends and professi
onal contacts that I most likely w
ould never had made otherwise. If
you like working with really nice peop
le, there is no better job. If there i
s one word to describe my experienc
e, it was FUN!” Each nominee must be a
membe
r
in good standing of the G-I f
or at least one year prior to the e
lection and be willing to serve on th
e Board for at least three year
s. The submission deadline is Friday
, March 26, 2010. For information: h
ttp://content.geoinstitute.org/file
modeling, and design. Be a part of
s/pdf/NominationsProcess.pdf Fifth
Fifth International Conference
on Scour and Erosion (ICSE)
November 7-10, 2010
Holiday Inn Gateway
San Francisco, CA.
www.icse-5.org
This G-I conference will highlight the
multi-disciplinary nature of scour
and erosion problems and solutions
which require approaches that merge
expertise in a wide variety of fields.
Planned discussion topics include
emerging theoretical developments,
field and laboratory studies, field
applications of technology, and case
histories. The conference will feature
keynote speakers in plenary sessions
followed by concurrent sessions.
ICSE-5 will also offer short courses
before the conference and technical
tours following the conference. Additional events include a welcome and
networking reception with posters in
the Exhibition Hall.
Professional Development Corner
March 2, 2010: Noon-1:30 p.m. ET:
An Overview of Geosynthetics and
Their Major Applications
March 10 & 17: Noon-1:30 PM ET:
(LRFD) for Geotechnical Engineering,
Two-Part Series
For information: https://secure.asce.org/
ASCEWebsite/Webinar/ListWebinar.aspx
Symposium on Benchmarking
Surface Wave Method
Geo-Risk Conference
Summer 2011
Call for Participation Deadline:
March 31, 2010
Practitioners and researchers are
invited to this symposium organized
by the G-I’s Geophysical Engineering
Committee. This symposium will
document the state of different
protocols, such as Multichannel
Analysis of Surface Waves (MASW),
Spectral Analysis of Surface
Waves (SASW), and Refraction
Microtremor (ReMi), for analyzing
the surface wave data. The Organizing
Committee requests submissions
to the benchmarking exercise by
analyzing a surface wave data set
collected at a well-characterized site.
Participants can also provide written
papers for inclusion in a symposium
that will be organized as part of the
symposium. For information: http://
saswbench.ce.ufl.edu. Questions? Dr.
Dennis Hiltunen at [email protected].
G-I Twitter Brings You Quick
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for posting very brief updates, or
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updates to its website and other
relevant news items. Since then,
over 240 updates have been posted
and more than 230 persons have
become registered G-I followers.
Visit our Twitter feed at http://twitter.
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GeoX 2010
www.cee.lsu.edu/geox2010/
workshop/default.htm
GeoX2010, the 3rd International
Workshop on X-Ray CT for
Geomaterials, March 1-3, 2010,
New Orleans, LA is co-sponsored
by the Geo-Institute. The conference
will serve as an exchange forum
to discuss the latest advances and
developments in the applications
of x-ray computed tomography.
Keynote lecturers include: Dr. Cino
Viggiani who will present the lecture
“Sand deformation at the grain scale
quantified through x-ray imaging”;
Dr. Tim Senden who will present
“Micro-petrophysical experiments via
tomography and simulation”; and
Dr. Anders Kaestner’s “Geological
samples analyzed with neutron
imaging methods” as the kickoff for
the session which includes novel
technologies.
Members in
the News
Ronald J. Ebelhar Joins
ASTM International Board of
Directors
Ronald J.
Ebelhar,
a senior
principal
with H.C.
Nutting, a
Terracon
company in
Cincinnati,
OH, was
named to
Ronald Ebelhar
a threeyear term on the ASTM International
board of directors. Ebelhar joined
McClelland Engineers in Houston, TX
as a staff engineer/consultant in 1977
for a 10-year span. He then served as
division manager and vice president
for Rust Environment & Infrastructure
(and its predecessors, S&ME,
Westinghouse and SEC Donohue)
in Cincinnati, OH, before taking the
position of vice president with H.C.
Nutting in 1996. He assumed his
current role in 2007.
As a project manager for geotechnical
and environmental engineering
projects worldwide, Ebelhar has
provided design and consulting
services for commercial, industrial,
transportation, waste disposal, and
public utility projects; geotechnical
53
CORE BITS
engineering design and construction, including site soil
response under seismic, cyclic and dynamic loadings; and
marine geosciences and engineering field explorations.
Ebelhar, who joined ASTM International in 1980, serves
as chair of Committee D18 on Soil and Rock. An ASTM
fellow and 2003 Award of Merit recipient, he received
the R.S. Ladd Standards Development Award in 2008
for D7400, Test Methods for Downhole Seismic Testing;
the Woodland G. Shockley Award in 2007; the A .Ivan
Johnson Outstanding Achievement Award in 2002; Special
Service Awards in 1993 and 1986; and the Committee D18
Technical Editor’s Award for STP 1213, Dynamic Geotechnical
Testing II, in 1995.
Marinucci Joins ADSC Staff
Antonio Marinucci, P.E., recently joined the ADSC
headquarters staff as Director of Member Services as he
completes his Ph.D. studies in geotechnical engineering
at the University of Texas at Austin. Tony brings several
years of experience working for geo-construction specialty
contractors, a major general contractor, and geotechnical
54
engineering firms in a variety
of capacities including project
management and deep
foundation and anchored earth
retention design. His credits
include participating in several
geo-engineering and construction
research projects. He is the
current secretary of the GeoInstitute’s Deep Foundations
Committee, and the Soil
Improvement Committee. Tony
Tony Marinucci
has also been an active volunteer
and committee member for many ADSC, ASCE, and DFI
initiatives.
McCook Becomes ASDSO Honorary Member
Danny K. McCook, P.E., was selected as an Honorary
Member of The Association of State Dam Safety Officials
(ASDSO) by its Board of Directors in 2009. McCook is
an independent consultant specializing in geotechnical
review and design of earthen embankments and levees. He
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weigh 20-25 tons. Our CPT rigs are based out of
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In addition to the heavier CPT rigs, we use an
extendable rod guide, hydraulic clamping system
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us the ability to push deeper and through denser
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transmittal capabilities directly from the field, several
smaller “anchor down” limited access CPT rigs and
many other capabilities including soil, vapor and
groundwater sampling. Please check out our
website at www.kehoetesting.com or call our office
for additional information.
We designed KTE’s rigs knowing the tremendous
advantage of having CPT rigs with 20-25% higher
pushing capacity. We are often called out to sites
where other CPT vendors have hit shallower
“refusal.” Why not use a larger CPT rig for your next
CPT project? Because when using CPT, BIGGER
is BETTER!!!
(l to r) ASDSO President David Gutierrez and McCook
retired in October 2008 after working for over 40 years
as a civil engineer and geotechnical specialist with the
National Design, Construction, and Soil Mechanics Center
of the USDA Natural Resources Conservation Service
in Fort Worth, TX. He has extensive experience in filter
design, modeling for stability, seepage, and consolidation
analyses. McCook has participated in numerous forensic
evaluations and has designed over 500 small earthen
embankments in the National Resources Conservation
Service (NRCS) programs. He also has presented papers at
16 ASDSO meetings and presented webinars on reviews
for embankment projects. McCook authored numerous
publications used by the NRCS for criteria and guidance
in the design of earthen embankments. He is a registered
professional engineer in Texas and a member of ASCE, the
United States Society on Dams (USSD), and the Association
of State Dam Safety Officials (ASDSO).

Edward Graf



5415 Industrial Drive
Huntington Beach, CA 92649-1518
Office (714) 901-7270 / Fax (714) 901-7289
www.kehoetesting.com
56
In Memoriam: Edward Graf
The grouting industry has lost a “Grouting Great.” Edward
Dutton Graf, former Geo-Institute member and pioneer
in grouting and foundation engineering, passed away of
lung disease on December 16, 2009 at Kaiser Hospital
FIND OUT MORE
TOLL FREE 877-846-3165
WWW.GEOSTRUCTURES.COM
Engineered Earth Structures & Foundations
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CORE BITS
in Honolulu, HI. He was just two weeks shy of his 85th
birthday. A native Californian, Graf was a World War II
Navy veteran, engineer, contractor, inventor, consultant,
and pilot. His technical and professional achievements
included: ASCE – Life Member and past chair of Committee
552 – Geotechnical Cement Grouting; ASCE Grouting
Committee past chair; Martin S. Kapp Foundation
Engineering Award, 1990; Fellow ACI (American Concrete
Institute); Who’s Who in Engineering since 1982; six pressure
grouting patents; and nine published papers. Read his
obituary at: http://content.geoinstitute.org/files/pdf/EGraf.pdf
G-I Organizational
Member News
GRL and PDI Retain Authorized Provider Status
The International Association for Continuing Education
and Training (IACET) renewed GRL Engineers and Pile
Dynamics’ prestigious Authorized Provider status through
2010. Providers are the only organizations approved to
offer IACET Continuing Education Units (CEUs). The
Florida Board of Professional Engineers also renewed GRL
Engineers’ status as an Authorized Provider of Professional
Development Hours in Florida through 2011.
“GRL and PDI are proud of our education programs which
train more than 120 engineers each year in foundation
testing and analysis skills so that they stay on the cutting
edge,” stated Gina Beim, P.E., who manages the continuing
education and training programs for the companies.
To retain this status, the companies completed a rigorous
application process, including a review by an IACET site
visitor, and successfully demonstrated adherence to the
ANSI/IACET 1-2007 Standard addressing the design,
development, administration, and evaluation of its
programs. A similar process was necessary to retain the
status of provider in Florida.
GRL has been providing deep foundation testing and
analysis services for more than 35 years. Sister company
PDI manufactures state-of-the-art systems for deep
foundation testing and installation monitoring.
Kleinfelder Selected for UDOT I-15
Reconstruction Project
Kleinfelder was selected to perform geotechnical services
58
for the Utah County I-15 Corridor Expansion (I-15
CORE) project. The project is Utah’s first attempt at a
“fixed-price/best-design” project. Kleinfelder is part of the
Provo River Contractors (PRC) team and their contract
is for $10.8 million to $13.6 million of the $1.7 billion
project. Kleinfelder will perform geotechnical services with
challenges such as ground settlement, embankment slope
stability, liquefaction, lateral spreading and seismic activity.
“We are so proud to be a part of the team that was
selected for this important project in one of our country’s
fastest-growing counties,”said Houman Makarechi, P.E.,
Kleinfelder senior vice president and transportation division
manager. “Our team’s dedication, expertise, and experience
in the transportation sector all played an important role in
our success.”
Moretrench
Moretrench American
Corporation
chairman John
Donohoe died on
December 2, 2009.
He had served as
chairman since 1995.
Donohoe joined
Moretrench in 1964,
immediately after
graduating from
the University of
Notre Dame with
a degree in civil
engineering. Over
John Donohoe
the course of a long
and distinguished career
with the company, he
advanced to hold the positions of president from 1982 to
2002 and chief executive officer from 1995 to 2007.
Throughout his career, he was active in the civil engineering
community. He served as President of the Construction
Institute of ASCE, President of AGC of New Jersey,
National Director of AGC of America, President of The
Moles, and President and Trustee of CIAP of New Jersey.
He was selected as Man of the Year of AGC of New
Jersey in 2001 and in 2004 received The Moles Award for
Outstanding Achievement in Construction, a tribute to
his lifetime accomplishments. He was a 2009 recipient
of the prestigious ASCE Opal Award for “innovation and
excellence in construction of civil engineering projects
and/or programs.” Most recently, he was elected president
of GCA of New York. Read his obituary at http://content.
geoinstitute.org/files/pdf/JFDObituaryProfessionalOrgs.doc
An engineering scholarship fund was established in John’s
name. Mail donations to the John F. Donohoe Scholarship
Fund c/o Moretrench American Corporation, 100 Stickle
Avenue, Rockaway, NJ 07866. Contact Moretrench American
at 973.627.2100 for details. Alternatively, donations can
be made to St. John’s Soup Kitchen, 22 Mulberry Street,
Newark, NJ 07122.
Nicholson Awarded Treatment Contract at
Hanford Site
CH2M HILL Plateau Remediation Company (CH2M HILL)
recently awarded Carpenter Drilling and Nicholson a
construction subcontract worth $330K for a jet injection
test program at the U.S. Department of Energy’s 100N Area
on the Hanford Site in Richland, WA. The test program is
expected to take approximately three weeks to complete.
Using jet grouting methods, Nicholson will construct three
permeable reactive barrier test sections by injecting ground
fishbone slurry, known as apatite, as well as a phosphate
solution. Permeable reactive barriers in the 100N Area are
being designed to protect the nearby Columbia River by
sequestering and immobilizing strontium-90 in the soil and
groundwater so it can safely decay in place.
Fishbone and phosphate solutions will be injected using
Nicholson’s proprietary JETPLUS jet grouting system.
Terra ‘s Book Value per Share Sets Another
Record
Terra Insurance Company’s book value per share set
another new all-time high at the end of the third quarter,
reaching $260.06 at September 30, 2009. This represents a
7.1% increase since January 1, 2009. Terra’s earnings since
January 1 were $10.39 per share, almost 20% ahead of what
they were on September 30, 2008.
“Terra has generated net income in every calendar quarter of
its existence as a risk retention group,” said Terra President
and CEO David L. Coduto. “This is not the first economic
downturn we’ve weathered profitably, and I’m confident it
won’t be the last.”
Terra provides a variety of professional liability insurance
products to civil, environmental, and geoprofessional
engineering firms that gross from $300,000 to more than
$100 million annually.
G-I Chapter News
Expand Your GT Group’s Exposure. Become a G-I
Chapter.
Increase your membership recruitment efforts by converting
your ASCE Section/Branch Geotechnical Group to a
G-I Chapter or by forming a G-I Chapter. It is strongly
encouraged by ASCE, and no fees or dues are required. The
simple process to become a G-I Chapter is posted on the
G-I Web site at http://content.geoinstitute.org/groups/index.html.
Benefits of affiliating with the G-I are also posted, as is a
PowerPoint presentation.
Allied Organizations
2011 Pan-Am CGS Geotechnical Conference
October 2-6, 2011
Toronto, Ontario, Canada
www.panam-cgc2011.ca/
The Canadian Geotechnical Society and the International
Society for Soil Mechanics and Geotechnical Engineering,
invite you to the 14th Pan-American Conference on Soil
Mechanics and Geotechnical Engineering (PCSMGE), the
64th Canadian Geotechnical Conference (CGC) and the
5th Pan-American Conference on Teaching and Learning of
Geotechnical Engineering (PCTLGE) at the Sheraton Centre
Hotel in Toronto, Ontario, Canada.
6ICEG - 2010
Sixth International Congress on Environmental
Geotechnics
November 8-12, 2010
New Delhi, India
www.6iceg.org
The Indian Geotechnical Society (IGS) will host this
conference on behalf of the International Society for Soil
Mechanics and Geotechnical Engineering (ISSMGE). The
Organizing Committee is guided by a Conference Advisory
Committee, as well as the TC5 (Technical Committee on
Environmental Geotechnics) of ISSMGE, and a National
Advisory Committee of IGS. The theme of the Congress is
Environmental Geotechnics for Sustainable Development.
More than 400 delegates, including 250 from abroad, will
59
CORE BITS
gather to discuss latest developments. Previous Congress
locations include: Edmonton, Canada (1994), Osaka, Japan
(1996), Lisbon, Portugal (1998 ), Rio de Janeiro, Brazil
(2002), and Cardiff, UK (2006).
Thomas Selected U.S. Professor of the Year
“Design, Analysis, and Failures of Geosynthetically Reinforced Retaining Walls and Steep Soil
Slopes” Short Course
This March 31, 2010 short course will be held at the
Geosynthetic Institute, 475 Kedron Avenue, Folsom, PA.
The course will present the origin, growth, and costs of
mechanically stabilized earth walls and soil slopes using
geosynthetic (geotextiles and geogrids) reinforcement.
Design and analysis will be focused on and illustrated
using two computer codes; MSEW and ReSSA, generated
for the Federal Highway Administration by Professor
Leshchinsky. Wall and slope failures will be presented
along with the major cause of such failures, lack of drainage
considerations. Proper drainage designs will then be
explained. Throughout the course, the various geosynthetics
tests necessary for design will be demonstrated. Eight PDH’s
are available. For information: http://content.geoinstitute.org/
files/pdf/GSIOneDayShortCourseDesignAnalysisFailures.doc
Industry News
New Discoveries Could Improve Climate
Projections
New discoveries about the deep ocean’s temperature
variability and circulation system could help improve
projections of future climate conditions. The deep ocean
is affected more by surface warming than previously
thought, and this understanding allows for more accurate
predictions of factors such as sea level rise and ice volume
changes. High ocean surface temperatures have also been
found to result in a more vigorous deep ocean circulation
system. This increase results in a faster transport of large
quantities of warm water, with possible impacts including
reduction of sea ice extent and overall warming of the
Arctic. “The deep ocean is relatively unexplored, and we
need a true understanding of its many complex processes”,
said U.S. Geological Survey Director Marcia McNutt. An
understanding of climate change and its impacts based
on sound, objective data is a keystone to the type of longterm strategies and solutions that are being discussed now
at the United Nations conference in Copenhagen. For
information:
www.clim-past.net/5/769/2009/cp-5-769-2009.html
60
Rob Thomas (r) with geology student, Stetson Wilson. Photo
courtesy of the University of Montana Western.
University of Montana Western environmental sciences
professor Rob Thomas was named Outstanding
Baccalaureate Colleges Professor of the Year by The
Carnegie Foundation for the Advancement of Teaching and
the Council for Advancement and Support of Education
(CASE).
Thomas has been a faculty member at Montana Western
for 16 years. During that time, he helped transform the
institution into the first and only public university in
the U.S. to offer block scheduling. Under this scheduling
system, students take one class at a time, three hours per
day for eighteen days earning the same credits over a year
as students do in traditional multiple-course scheduling
models.
Thomas left a tenure track position in the Ivy League at
Vassar College because he recognized Montana Western’s
potential. He states that his and Montana’s Western’s recent
successes are particularly gratifying. For more information:
http://news.umwestern.edu/2009/11/rob-thomas-selected-u-sprofessor-of-the-year/
Fifth International Conference on Recent
Advances in Geotechnical Earthquake Engineering and Soil Dynamics
http://5geoeqconf2010.mst.edu
Registration is open for this May 24-29, 2010, San Diego,
GEO_EDTseries_ad.qxd:UTF_EDT7_05_ad.qxd
CA conference and symposium in
honor of professor I.M. Idriss. Register
now to select the best spot for your
booth and obtain the reduced early
registration fee. Professionals from
more than 40 countries will present
their recent research findings. The
exchange of information during the
conference will advance the state of
the art and practice in several areas
and will give definitive direction
to future work. Earthquake, civil,
structural, and geotechnical engineers,
geologists, scientists, teachers,
builders, contractors, and other
professionals worldwide are invited
to attend and join in the discussion at
this conference.
1/11/10
12:06 PM
Page 1
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2009 NOVA Award
Winners
The 2009 NOVA award, instituted
in 1989 to recognize innovations
that have proven to be significant
advances that have had positive,
important effects on construction to
improve quality and reduce cost, was
recently presented to Michael Adams,
Robert Barrett, and Warren Schlatter,
P.E., P.S. This year, the Construction
Innovation Forum selected the
innovative project “Geosynthetically
Reinforced Soil (GRS) Bridge
Abutments in Defiance County,
Ohio” from among 35 nominations.
Adams works with the FHWA at the
Turner Fairbanks Highway Research
Center; Barrett serves on the Board of
Directors of Soil Nail Launcher, Inc.;
and Schlatter is the County Engineer
for Defiance County, OH.
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CONTECH Announces
January Price Increase
CONTECH Construction Products
Inc. announced a January 12, 2010
price increase for its corrugated metal
and PVC products. The price increase
will be 8.9% for all corrugated
metal products and 9.0% for all
PVC pipe products. “Increased order
activity in the steel industry along
with increased raw material and
steelmaking input costs from our
suppliers are the main reasons for this
price increase,” said Steve Spanagel,
president of CONTECH Sales.
61
CORE BITS
Geo-Institute
Upcoming
Conferences
International Conference on Scour and Erosion
November 7-10, 2010
Holiday Inn Gateway
San Francisco, California
www.icse-5.org
Visit www.geoinstitute.org/events.html for links to these and
other upcoming events:
GeoFlorida 2010
February 20-24, 2010
Palm Beach County Convention Center
West Palm Beach Marriott
Hilton Palm Beach Airport
West Palm Beach, FL
www.geocongress.org
Geo-Frontiers 2011
March 13-16, 2011
Sheraton Dallas
Dallas, TX
www.geofrontiers11.com/
To submit information for Geo-Strata magazine, or
possible posting on the Geo-Institute website at www.
geoinstitute.org, send us brief news about your recent
honors, awards, special appointments, promotions, etc.
High-resolution photos must be sent as separate pdf, tif,
or jpeg files. Send to [email protected]. Sales-oriented
content should be directed to Dianne Vance, Director of
Advertising at [email protected].
Earth Retention 2010
August 1-August 4, 2010
Hyatt Regency Bellevue
Bellevue, WA
www.er2010.org
CE LLP HON E S
SAVE LIVES
IN HAITI.
Help the victims of the Haiti earthquake with the most important text message you’ll
ever send. Text “Haiti” to 90999 and a $10 donation will be added to your
phone bill.* Your contribution helps the Red Cross provide food, water and shelter.
Haiti is calling for help: Answer with a text.
Other ways to contribute:
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62
2010
Earth Retention 2010
August 1 - August 4, 2010
Hyatt Regency Bellevue
Bellevue, Washington
www.er2010.org
join us for these 2010 Geo-Institute conferences
International
Conference on
Scour and Erosion
November 7 - 10, 2010
Holiday Inn Golden Gateway
San Francisco, California
www.icse-5.org
ICSE-5
Advances in Geotechnical Engineering
MARK YOUR CALENDAR
FOR THE GEOTECHNICAL
EVENT OF 2011
Where engineering design and construction comes
together with dynamic products and applications
The objective of the Event is to share new developments in
geotechnical engineering technologies. Attendees will be
exposed to the latest state-of-the-art-and-practice as applied
to geotechnical engineering.
Abstracts due 8 March 2010
www.geofrontiers11.com
Geo-Frontiers 2011 is co-organized by
Under the auspices of
Includes GRI-24 Annual Conference

January/February 2010 - GEOSTRATA - Geo

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