UPDATED GEOTECHNICAL STUDY Oracle

Transcription

UPDATED GEOTECHNICAL STUDY
Oracle Education Facility
Redwood City, California
Prepared For:
Oracle
Prepared By:
Langan Treadwell Rollo
555 Montgomery Street, Suite 1300
San Francisco, California 94111
Peter D. Brady, PE
Senior Staff Engineer
John Gouchon, GE
Principal
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Updated Geotechnical Study
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TABLE OF CONTENTS
1.0
INTRODUCTION ............................................................................................................. 1
2.0
SCOPE OF SERVICES .................................................................................................... 1
3.0
SITE AND SUBSURFACE CONDITIONS ....................................................................... 2
4.0
REGIONAL SEISMICITY AND FAULTING ..................................................................... 2
5.0
GEOLOGIC AND SEISMIC HAZARDS ........................................................................... 4
6.0
DISCUSSION AND CONCLUSIONS .............................................................................. 5
6.1
Settlement.......................................................................................................... 5
6.1.2 Surcharging ............................................................................................ 6
6.1.3 Surcharge and Wick Drains ................................................................... 6
6.1.4 Settlement Considerations .................................................................... 6
6.2
Foundations ....................................................................................................... 7
6.2.1 Stiffened Shallow Foundation ............................................................... 7
6.2.2 Deep Foundations .................................................................................. 8
6.3
Corrosivity .......................................................................................................... 8
6.4
Construction Considerations ............................................................................ 9
7.0
RECOMMENDATIONS ................................................................................................... 9
7.1
Foundations ................................................................................................................... 9
7.1.1 Shallow Foundations ............................................................................. 9
7.1.2 Deep Foundations ................................................................................ 10
7.2
Earthwork ......................................................................................................... 14
7.2.1 Subgrade Preparation and Fill Placement .......................................... 14
7.2.2 Surcharge Fill ........................................................................................ 15
7.3
Wick Drain Installation .................................................................................... 15
7.4
Seismic Design ................................................................................................. 16
7.5
Floor Slabs........................................................................................................ 16
7.6
Underground Utilities ...................................................................................... 18
8.0
ADDITIONAL GEOTECHNICAL SERVICES.................................................................. 18
9.0
LIMITATIONS ............................................................................................................... 18
REFERENCES
FIGURES
APPENDICES
DISTRIBUTION
FIGURES
Figure 1
Site Location Map
Figure 2
Site Plan
Figure 3
Map of Major Faults and Earthquake Epicenters
in the San Francisco Bay Area
Figure 4
Modified Mercalli Intensity Scale
APPENDICES
Appendix A
Boring Logs
Appendix B
Soil Corrosivity Test Results
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UPDATED GEOTECHNCIAL STUDY
1.0
INTRODUCTION
This report presents the results of our geotechnical study for the proposed education facility at
the Oracle Headquarters in Redwood City, as shown on Figure 1. The center will be located on
the north side of Oracle Parkway as shown on Figure 2. The center will be across the Parkway
from the Conference Center and the 400 Oracle parking garage.
The site is between
Oracle Parkway and Belmont Slough. A levee separates the school site from Belmont Slough.
Treadwell & Rollo, Inc. previously issued a geotechnical report dated 5 March 2002 and an
environmental report dated 11 April 2001 for the Oracle Child Care Center; however, since
issuing those reports the proposed building layout and grading plans have changed.
The
previous reports should not be relied on for this project.
We understand plans for redeveloping the site will consist of demolishing the existing parking
areas and constructing a 75,000 square feet, 2-story building with site improvements,
landscaping and parking areas. The proposed building will be at-grade with a proposed finish
floor elevation of 111 feet1. Site grades vary from about Elevation 104.5 to 110 feet and about
Elevation 108 to 110 feet within the building pad; therefore up to about 2 feet of fill will be
required to construct the building pad. In addition we understand the levee will be raised as
part of the site grading for the school.
2.0
SCOPE OF SERVICES
Our study was performed in accordance with our proposal dated 13 March 2015. Our scope of
services for the geotechnical study consisted of reviewing available geotechnical data and
performing engineering analyses to develop conclusions and recommendations regarding:
1

soil and groundwater conditions at the site

appropriate foundation type(s)

design parameters for the foundation, including lateral load resistance and uplift capacity

estimates of foundation settlement and time rate of settlement
All elevations are referenced to Redwood City Datum
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
use of wicks and/or surcharging the site

subgrade preparation for slab-on-grade floors

site seismicity and seismic hazards

2013 California Building Code (CBC) soil profile type and mapped values SS and S1 and
coefficients Fa and Fv

evaluation of corrosion potential of the near surface soil

construction considerations.
A geotechnical report for the entire Oracle Campus (formerly the Marine World theme park)
was prepared by Lee & Praszker, Inc. in 1985. We have reviewed this report as well as other
pertinent documents, including previous site investigations and site grading reports. Treadwell
& Rollo, Inc., has provided geotechnical services for several of the Oracle office buildings,
parking garages, and the recreation center and geotechnical information from these sites was
used where applicable. Copies of pertinent boring logs are included in Appendix A.
3.0
SITE AND SUBSURFACE CONDITIONS
The site of the proposed education facility is between the levee and Oracle Parkway. It is
essentially level; ground surface elevations vary from 104.5 to 108 feet. The western quarter of
the site is currently vacant with sparse vegetation and the remaining portion of the site is a
paved parking lot. Plans indicate the site may have been occupied by maintenance buildings
that were part of the former Marine World theme park; these were demolished as part of the
Oracle development.
Our review of previous reports indicates the area is blanketed by about 5 to 6 feet of clayey
sand fill that is underlain by about 23 to 25 feet of compressible clay, known locally as Bay
Mud. The Bay Mud is underlain by interlayered stiff clay and medium-dense sand.
Groundwater was recorded at Elevation 101 feet in nearby borings and has been observed at
about this elevation in open utility trenches during various phases of construction of the
existing facilities.
4.0
REGIONAL SEISMICITY AND FAULTING
The major active faults in the area are the San Andreas, San Gregorio, Hayward, and Calaveras
Faults. These and other faults of the region are shown on Figure 3. For each of the active
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faults within about 100 kilometers of the site, the distance from the site and estimated mean
characteristic Moment magnitude2 [2007 Working Group on California Earthquake Probabilities
(WGCEP) (2008) and Cao et al. (2003)] are summarized in Table 1.
TABLE 1
Regional Faults and Seismicity
Fault Segment
N. San Andreas – Peninsula
N. San Andreas (1906 event)
Monte Vista-Shannon
San Gregorio Connected
Total Hayward
Total Hayward-Rodgers Creek
Total Calaveras
N. San Andreas - North Coast
Mount Diablo Thrust
N. San Andreas - Santa Cruz
Green Valley Connected
Greenville Connected
Zayante-Vergeles
Rodgers Creek
Great Valley 5, Pittsburg Kirby Hills
Point Reyes
Great Valley 7
Monterey Bay-Tularcitos
West Napa
Great Valley 4b, Gordon Valley
Ortigalita
Great Valley 8
Approx.
Distance from
fault (km)
Direction
from Site
Mean
Characteristic
Moment
Magnitude
7
7
11
20
23
23
34
39
42
46
48
53
56
64
65
68
69
69
70
88
92
98
West
West
South
West
Northeast
Northeast
East
Northwest
Northeast
Southeast
Northeast
East
Southeast
North
Northeast
Northwest
East
South
North
Northeast
East
East
7.23
8.05
6.50
7.50
7.00
7.33
7.03
7.51
6.70
7.12
6.80
7.00
7.00
7.07
6.70
6.90
6.90
7.30
6.70
6.80
7.10
6.80
Figure 3 also shows the earthquake epicenters for events with magnitude greater than 5.0 from
January 1800 through August 2014. Since 1800, four major earthquakes have been recorded
on the San Andreas Fault. In 1836 an earthquake with an estimated maximum intensity of VII
on the Modified Mercalli (MM) scale (Figure 4) occurred east of Monterey Bay on the
San Andreas Fault (Toppozada and Borchardt 1998). The estimated Moment magnitude, Mw,
for this earthquake is about 6.25. In 1838, an earthquake occurred with an estimated intensity
of about VIII-IX (MM), corresponding to a Mw of about 7.5. The San Francisco Earthquake of
2
Moment magnitude is an energy-based scale and provides a physically meaningful measure of the size of a
faulting event. Moment magnitude is directly related to average slip and fault rupture area.
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1906 caused the most significant damage in the history of the Bay Area in terms of loss of lives
and property damage. This earthquake created a surface rupture along the San Andreas Fault
from Shelter Cove to San Juan Bautista approximately 470 kilometers in length.
It had a
maximum intensity of XI (MM), a Mw of about 7.9, and was felt 560 kilometers away in Oregon,
Nevada, and Los Angeles. The Loma Prieta Earthquake occurred on 17 October 1989, in the
Santa Cruz Mountains with a Mw of 6.9, approximately 65 km from the site.
In 1868 an
earthquake with an estimated maximum intensity of X on the MM scale occurred on the
southern segment (between San Leandro and Fremont) of the Hayward Fault. The estimated
Mw for the earthquake is 7.0. In 1861, an earthquake of unknown magnitude (probably a M w of
about 6.5) was reported on the Calaveras Fault. The most recent significant earthquake on this
fault was the 1984 Morgan Hill earthquake (Mw = 6.2).
The most recent earthquake to affect the Bay Area occurred on 24 August 2014 and was
located on the West Napa fault, approximately 70 kilometers northeast of the site, with a M w of
6.0.
The 2007 WGCEP at the U.S. Geologic Survey (USGS) predicted a 63 percent chance of a
magnitude 6.7 or greater earthquake occurring in the San Francisco Bay Area in 30 years.
More specific estimates of the probabilities for different faults in the Bay Area are presented in
Table 2.
TABLE 2
WGCEP (2008) Estimates of 30-Year Probability
of a Magnitude 6.7 or Greater Earthquake
Fault
5.0
Probability
(percent)
Hayward-Rodgers Creek
31
N. San Andreas
21
Calaveras
7
San Gregorio
6
Concord-Green Valley
3
Greenville
3
Mount Diablo Thrust
1
GEOLOGIC AND SEISMIC HAZARDS
Considering the proximity of the site to nearby potentially active faults, we conclude that strong
ground shaking could occur during a major earthquake on one of these faults. Strong shaking
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during an earthquake can result in ground failure such as that associated with soil liquefaction3,
lateral spreading4, and cyclic densification5.
On the basis of our review of the borings, we conclude the sand layers are dense enough or
have sufficient cohesion to resist liquefaction. We also conclude that the potential for cyclic
densification and lateral spreading is very low.
Historically, ground surface displacements closely follow the trace of geologically young faults.
No active faults or extensions of active faults have been mapped as passing through or
adjacent to the site.
Therefore, we conclude the risk of surface faulting and consequent
secondary ground failure is very low.
6.0
DISCUSSION AND CONCLUSIONS
The compressibility of the Bay Mud is the primary concern for design of the proposed
education facility. Settlement will result when additional fill and foundation loads are placed.
The primary factor controlling selection of an appropriate foundation system is the present state
of consolidation of the Bay Mud. Our discussion and conclusions regarding the geotechnical
issues and their impact on the design and construction of the proposed improvements are
presented in the following sections.
6.1
Settlement
The results of our analyses indicate that while the primary consolidation of the Bay Mud layer
due to the existing fill is complete, the construction of new structures and placement of new fill
at the site would begin a new cycle of consolidation of the Bay Mud resulting in ground surface
settlement.
The amount and time rate of consolidation settlement depends upon: 1) the
weight of any new fill and/or structural loads, 2) the thickness of the existing fill, 3) the
thickness of the Bay Mud deposit, 4) the degree to which desiccation has overconsolidated the
upper portion of the Bay Mud deposit, and 5) the presence of sand layers within the Bay Mud
deposit. These factors vary across the site making it difficult to generalize the amount of total
and differential settlement expected beneath improvements.
3
Liquefaction is a transformation of soil from a solid to a liquefied state during which saturated soil temporally
loses strength resulting from the buildup of excess pore water pressure, especially during earthquake-induced
cyclic loading. Soil susceptible to liquefaction includes loose to medium dense sand and gravel, low-plasticity
silt, and some low-plasticity clay deposits
4
Lateral spreading is a phenomenon in which surficial soil displaces along a shear zone that has formed within an
underlying liquefied layer. Upon reaching mobilization, the surficial blocks are transported downslope or in the
direction of a free face by earthquake and gravitational forces.
5
Cyclic densification is a phenomenon in which non-saturated, cohesionless soil is compacted by earthquake
vibrations, causing ground surface settlement.
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Based on topographic maps of the site vicinity and discussions with the project civil engineer,
BKF, up to 2 feet of fill will be placed in portions of the building pad to raise site grades. We
estimate long term consolidation settlement of about 3.5 inches per foot of new fill and less
than an inch in areas that will not be filled. Consequently, differential settlements may be the
greatest at the transition from fill to no fill.
In addition, we estimated the combined total
settlements due to the weight of the school building (assuming a uniform building pressure of
500 psf), and new fill to bring the site up to the building pad. We estimate total settlements
between 10 and 18 inches within the footprint of the building that will receive fill, and up to 8.5
inches within the building footprint that will not be filled. Estimated settlements along the
perimeter and center of the building were transmitted to the design team. We estimate that it
will take approximately 10 to 15 years for primary settlement to be complete.
6.1.2
Surcharging
Because of the large estimated settlements from the weight of fill and building, we performed
additional settlement analysis to evaluate the effectiveness of surcharging the site.
The amount of settlement resulting from surcharging the site would depend upon the duration
of the surcharge and the amount of fill used. On the basis of discussions with the design team
we understand because of the anticipated construction schedule the duration of the surcharge
program would be about 4 months. Therefore, in our analysis, we modeled a stockpile of soil
10 feet high for a period of 4 months. We estimated the remaining settlements within the
building pad would range from 5 to 12 inches and 2 to 3 inches outside the building footprint,
after the surcharge is removed and the school is constructed.
6.1.3
Surcharge and Wick Drains
Because of the significant amount of settlement that would remain after the surcharge
program, it was decided to include wick drains in the analysis. Wick drains consist of 4-inch
wide prefabricated strips that are installed with a mandrel through the soft clays to accelerate
consolidation settlement. They are installed in a triangular pattern typically at 4- to 7-feet on
center spacing. The closer the spacing the faster the settlement can occur.
For a 4 foot
triangular spacing between the wicks we estimate the site will settle between 1.5 feet and
2 feet after 5 months of surcharge with wick drains. After the surcharge is removed and the
building is constructed, we estimate long term settlements will be less than one inch.
6.1.4
Settlement Considerations
Because the site is underlain by Bay Mud, some settlement should be anticipated over time,
even if the site is wicked and surcharged because of the potential for secondary settlement.
Ground surface settlements will tend to distort and crack the pavements and exterior
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improvements such as sidewalks. Periodic repairs and replacement of these improvements
should be expected during the life of the project. Mastic joints or other positive separations
should be provided to permit relative movements between exterior slabs and the education
center.
Immediately adjacent to the building entrances, articulated hinge slabs should be
provided. The slabs should permit rotation of the slab as the building settles without creating
vertical offset at the entrance. We recommend flexible connections for utilities entering the
building.
Where fill is placed next to existing improvement such as Oracle Parkway it may cause
settlement and distress to those improvements. Depending on the magnitude of settlement it
may be necessary to repair the existing improvements.
Alternatively, in areas near
improvements, the weight of the new fill may be offset by excavating and replacing the
existing on-site fill with light-weight cell-crete or geofoam, such that the effective change in
stress is minor. For example light-weight cell-crete has a unit weight of about 35 to 40 pounds
per cubic foot. If three feet of on-site soil is replaced with three feet of cell-crete, then an
additional two feet of fill could be placed without causing significant settlement.
We should review the final grading plans to check that the assumptions used in our settlement
analysis are appropriate and revise our estimated settlement as appropriate.
6.2
Foundations
To support the proposed building, we evaluated three foundation alternatives:
footings 2) stiffened shallow foundation and 3) deep foundations.
1) isolated
We concluded that the
potential differential settlement of isolated footings would preclude the use of isolated footings.
6.2.1
Stiffened Shallow Foundation
If the anticipated settlements after surcharging the site and using wicks are acceptable, a
stiffened shallow foundation consisting of a grid or mat foundation can be used to support the
building.
A stiffened foundation will distribute the building loads more uniformly to the underlying Bay
Mud than would isolated footings. This will reduce the potential differential settlements across
the site and between individual columns. A typical stiffened foundation system consists of
interconnected continuous footings forming a grid. It is important to note that, although a
stiffened foundation is intended to reduce differential settlements across the building,
measurable total and differential settlements are expected. The existing Oracle Fitness Center
has this type of foundation system.
6.2.2
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Deep Foundations
If time does not permit for surcharging and wicking the site, the building can be supported on a
deep foundation consisting of piles and a structurally supported slab. Auger-cast piles (ACPs)
or similar pile types, which are low-vibration, low-noise, deep foundation options, are suitable
alternatives for the site.
ACPs are installed by drilling to the required depth with a hollow-stem, continuous-flight auger.
The auger has a reverse tread which results in displacement and densification of the
surrounding soil and results in little to no spoils. When the auger reaches the required depth,
cement grout or concrete is injected through the bottom port of the hollow stem auger. Grout
or concrete is injected continuously as the augers, still rotating in a forward direction, are slowly
withdrawn, replacing the displaced soil. While the grout is still fluid, a steel reinforcing cage is
inserted into the shaft. ACPs can range in diameter; however, 18- and 24-inch-diameter ACPs
are typical. ACPs will generate spoils during installation.
6.3
Corrosivity
Surface soil samples were evaluated for corrosivity by CERCO Analytical, Inc., a state-certified
laboratory in Pleasanton, California. Soil samples were collected from borings SB-4 and SB-9
during our previous 2001 environmental investigation at depths of 1.5 and 2.5 feet below
existing grade, respectively.
The samples were analyzed using ASTM Test Methods for
conductivity, chloride content, sulfate content, pH, and redox potential.
The test results are included in Appendix B and are summarized as follows: 1) the resistivity
measurements indicate the near-surface soil is severely corrosive to metals, 2) the chloride ion
concentrations are corrosive to steel embedded in a concrete mortar coating, 3) the sulfate ion
concentrations are sufficient to damage reinforced concrete structures and cement mortar
coatings, 4) the pH test results indicate the soil is acidic and presents a problem for buried
steel, mortar coated steel, and reinforced concrete structures, and 5) the redox potentials
indicate slightly corrosive soils resulting from anaerobic soil conditions.
On the basis of the corrosivity test, we conclude the near-surface soils at the site should be
considered as corrosive to metals, reinforced concrete, and cement mortar coating.
Appropriate corrosion protection measures should be implemented for metal and concrete in
contact with the soil. Corrosion of buried metal pipelines can be reduced by application of a
protective coating or by providing cathodic protection. Corrosion to reinforced concrete can be
reduced by using sulfate resistant cement (ASTM Type II or special mix designed to resist
corrosion) in accordance with California Building Code requirements for reinforced concrete that
will be in contact with the ground.
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A corrosion engineer should be consulted to develop
specific recommendations for corrosion protection.
6.4
Construction Considerations
If site grading is scheduled for the rainy season, typically between November and April, the
near-surface soil may be too wet to achieve adequate compaction during site preparation and
fill placement and may deflect significantly under the weight of construction equipment. For
these conditions, moisture conditioning of the native material and the use of lightweight and/or
track-mounted equipment may be required to lower the native soil to a moisture level that will
promote proper compaction. Methods of moisture conditioning include mixing and turning
(aerating) the soil to naturally dry the soil and lower the moisture content to an acceptable level.
Aeration typically requires at least a few days of warm, dry weather to effectively dry the
material. Other soil stabilization alternatives to provide a stable, workable subgrade for grading
operations and other equipment include overexcavating the wet soil and replacing with drier
material and/or lime/cement treatment.
If localized soft or wet areas are encountered, it may be necessary to overexcavate them to a
depth of 18 to 24 inches, place a geotextile fabric, such as Mirafi 500X or equivalent, at the
bottom of the overexcavation and backfill with granular material to stabilize the subgrade and
bridge the soft material.
7.0
RECOMMENDATIONS
Recommendations regarding site preparation, foundation design, floor slabs, and seismic
design are presented in the following sections
7.1
FOUNDATIONS
Based on our conversation with the project team, we understand that both shallow and deep
foundations are being considered for the proposed foundation systems. The following sections
provide recommendations for both foundation types.
7.1.1
Shallow Foundations
If settlements are acceptable, the building may be supported on interconnected continuous
footings and structural slab forming a grid system or mat. The grid portion of the system
should be embedded in undisturbed sandy fill and extend a minimum of 2 feet below the
adjacent top of floor slab and have a minimum width of 2 feet. We recommend that the
system be designed for a distributed bearing pressure beneath the footing grid of 1,500 pounds
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per square foot for dead plus adjusted live load, with a one-third increase for wind and/or
seismic. The weight of the footings may be neglected in calculating building loads, however,
the weight of the floor slab should be included. The grid system, including the slab, should be
designed with sufficient reinforcement to span an unsupported area 15 feet in diameter
anywhere within the building footprint. For design of a grid-type foundation we recommend
using a subgrade modulus of 6 kips per cubic foot (kcf).
Lateral loads may be resisted by a combination of passive earth pressure on the vertical faces
of the grid foundation and friction between the bottom of the grid and the supporting fill.
We recommend using a uniform passive resistance of 1,500 psf; the upper one foot of soil
should be ignored unless it is confined by a slab or pavement. Frictional resistance should be
computed using a base friction coefficient of 0.30.
These passive pressure and frictional
resistance values include a factor of safety of at least 1.5; the design can be based on these
values without additional factors of safety.
7.1.2
Deep Foundations
The proposed building may be supported on a deep foundation system consisting of drilled
auger-cast piles (ACP). The piles will primarily gain capacity from friction in clayey soil below
the Bay Mud. Recommendations for the design of drilled piles are provided in the following
subsections.
7.1.2.1
Axial Capacity
ACPs are proprietary piles and are installed by design-build or specialty contractors and we
cannot provide specific recommendations for their design. In the San Francisco Bay Area,
ACPs are installed by several experienced contractors.
We preliminarily estimate axial ultimate skin friction of approximately 2,200 pounds per square
foot (psf) in the soil below the Bay Mud. Because the site is expected to settle over time the
piles should be designed for downdrag loads.
We estimate downdrag loads for 16- and
18-inch-diameter ACPs will be about 25 and 30 kips respectively.
Typically the lengths of ACPs are about 80 to 90 feet. Greater lengths may be used, but it may
slow down production and limit the number of capable contractors. Therefore, in our analysis,
we have limited the length to 60 feet for ACPs. Final design axial pile capacities for ACPs
should be determined by the specialty/design building contractors after the pile type has been
chosen. For a 80-foot-long, 16- and 18-inch-diameter ACP, we preliminarily estimate the net
allowable dead plus live load will be about 230 and 260 kips, respectively, with a one third
increase for total loads including wind or seismic. The allowable loads include a safety factor of
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2 of dead plus live loads and 1.5 for total loads and are based on a tip elevation of about
25 feet.
Final design capacities should be verified by a test program. We recommend at least one
compression and one tension pile load tests should be performed per 2013 California Building
Code Section 1810.3.3.1.2.
Pile should be spaced at least three pile diameters center-to-center, to prevent vertical capacity
reductions due to pile interaction effects; the outer auger-tip diameter should be used when
determining the pile spacing for ACP piles. The piles should also be designed to account for
the presence of corrosive soil; a corrosion consultant should be retained to provide specific
recommendations regarding the long term corrosion protection of pile elements.
7.1.2.2
Lateral Load Resistance
The piles should develop lateral resistance from the passive pressure acting on the upper
portion of the piles and their structural rigidity. The allowable lateral capacity of the piles
depends on:

the pile stiffness

the strength of the surrounding soil

axial load on the pile

the allowable deflection at the pile top and the ground surface

the allowable moment capacity of the pile.
We preliminarily evaluated the lateral capacity of the 16-inch and 18-inch-diameter ACPs for
1/2-inch deflection at the pile head. For a free-head condition, the pile top is free to move
laterally and rotate. For a fixed-head condition, the pile top is restrained from rotating but free
to move laterally. The results of our analyses are presented in Table 3 below.
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TABLE 3
Preliminary Lateral Pile Capacities for ½-Inch Pile Top Deflection
Free-Head Condition
Fixed-Head Condition
Depth To
Lateral
Maximum
Maximum
Lateral
ACP Diameter
Capacity
Moment
Moment
Capacity
Maximum Moment
(inches)
(kips)
(kip-ft)
(ft)
(kips)
(kip-ft)
16
15
53
5
30
129
18
19
97
6
36
166
Once the final pile type has been determined, we can provide the appropriate moment profiles
for single piles upon request.
The lateral capacities in Table 3 are for single piles only. To account for group effects, the
lateral load capacity of a single pile should be multiplied by the appropriate reduction factors
shown on Table 4. However, the maximum moment for a single pile with an unfactored load
should be used to check the design of individual piles in a group. The reduction factors are
based on a minimum center-to-center spacing of three pile widths. Where piles are spaced at
least six pile diameters in all directions, no group reduction factors need to be applied.
Reduction for other pile group spacing can be provided once the number and arrangement of
piles are known.
TABLE 4
Lateral Group Reduction Factors
Number of Piles
Lateral Group
within Pile Cap
Reduction Factor
2
0.9
3 to 5
0.8
>6
0.7
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Additional lateral load resistance can be developed by passive resistance acting against the
faces of the pile caps and grade beams. Passive resistance may be computed using a uniform
(rectangular) distribution of 1,500 psf. The upper foot should be ignored unless it is confined by
a slab.
Frictional resistance should be computed using a base friction coefficient of 0.30.
These values have a factor of safety of about 1.5 and may be used in combination without
reduction.
If there is insufficient lateral capacity from the piles, pile caps, and grade beams, the lateral
capacity of the system can be increased by adding piles or deepening grade beams.
7.1.2.3
Indicator and Pile Load Test Program
We recommend that before production ACP pile lengths are selected, indicator piles be
installed to: 1) evaluate predrilling requirements, if any, and 2) estimate production pile lengths.
We recommend a minimum of eight indicator piles be installed within the building footprint.
We expect the indicator piles can be used for support of the proposed structure if installed in
the proper location and are not damaged during installation or testing. If indicator piles are to
be removed following the indicator program, then the indicator piles should be located at least
seven pile diameters (center-to-center) from production pile locations. Indicator piles should be
installed with the same equipment and using the same procedure, including predrilling depth
and predrill auger diameter, that will be used for production piles.
In addition, we recommend load tests of the ACPs be performed to confirm the axial
compression and tensile pile capacities. We recommend a minimum of one compression and
one uplift load tests be performed for each proposed production pile installation methodology
(i.e. rig type, predrilling depth and diameter, pile length, etc.) The test pile locations should be
selected by the geotechnical engineer and approved by the structural engineer.
The
compression load tests should be performed in accordance with ASTM D1143-07, Standard
Test Method for Piles Under Static Axial Compressive Load, and the tension tests should be
performed in accordance with ASTM D3689-07. Either the standard or quick method can be
used. Equipment used for the test (load frame, jacks, and reaction piles) should be capable of
applying at least 2.5 times the allowable dead plus live design load and at least 2 times the total
load to account for the downdrag loads and neglecting the contribution of the fill and Bay Mud
during the load test. The Davisson Method or other accepted criteria per the 2013 California
Building Code should be used to interpret the ultimate capacities of the piles.
7.1.2.4
22 June 2015
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Pile Installation Work Plan
A work plan should be submitted to the Geotechnical Engineer for review and approval at least
five working days prior to the indicator pile and pile load test programs. The plan should
specify: the proposed pile installation equipment and methodology, including, but not limited to,
predrilling depth, diameter of auger used for predrilling, pile diameter and pile length and
corrosion allowance or protection, as well as the proposed pile load test set-up and procedure
and proposed test pile to check the condition of epoxy coating (if used) after installation. The
work plan should include a site plan showing the locations of indicator test and reaction piles
relative to permanent foundation elements and a drawing showing the layout of the load test
set up. Following the completion of pile load tests, the Geotechnical Engineer will require at
least three working days to review and evaluate the load test results and propose
recommendations for production pile installation. The structural engineer should review mill
certificates for the steel and any welding procedures.
Additional pile load tests will be required if, during production pile installation, the equipment or
installation procedure deviates from the approved work plan and indicator pile load test
program.
7.2
Earthwork
7.2.1
Subgrade Preparation and Fill Placement
The site should be stripped of any organic topsoil; the stripped soil may be stockpiled for later
use as fill in landscaped areas.
In areas to be filled, the ground surface exposed during
subgrade preparation should be kept moist. The exposed subgrade should be compacted to
90 percent relative compaction.
On-site soil should be suitable for use as fill or backfill. If earthwork takes place during the rainy
season, it may take time to dry the soil sufficiently to properly compact it. If it cannot be dried,
lime or cement treatment may be needed so the soil can be properly compacted. This could
significantly increase the cost of grading.
All fill should be free of organic matter, construction debris, and rocks or lumps larger than
three inches in greatest dimension. Imported (select) fill material should have a low expansion
potential (defined by a liquid limit less than 40 and a plasticity index lower than 12), contain less
than 20 percent fines (particles passing the No. 200 sieve), and be approved by the
geotechnical engineer. A sample of the on-site subgrade material, or material to be used as fill
(either on-site or import) should be submitted to the geotechnical engineer for testing at least
three business days prior to use at the site.
22 June 2015
730163312
Page 15
All fill should be placed in lifts not exceeding eight inches in uncompacted thickness and
compacted to at least 90 percent relative compaction6. However, if imported clean sand or
gravel is used as backfill, it should be compacted to at least 95 percent relative compaction.
Jetting of trench backfill should not be permitted.
7.2.2
Surcharge Fill
We performed our settlement analyses based on 10 feet of soil placed above existing grade.
Because the ground is expected to settle almost two feet the lower two feet of the surcharge
should be compacted to at least 90 percent relative compaction. The remaining fill used to
surcharge the site should be imported and placed and compacted to at least 85 percent relative
compaction.. We recommend the surcharge extend a minimum 5 feet outside the building pad
footprint. The sides of the surcharge stockpile should be sloped for safety in accordance with
the Occupational Safety and Health Administration (OSHA) standards (29 CFR Part 1926).
Inclinations of temporary slopes should not exceed those specified in local, state or federal
safety regulations. As a minimum, the requirements of the current OSHA Health and Safety
Standards for Excavations (29 CFR Part 1926) should be followed.
The Contractor should
determine temporary slope inclinations based on the subsurface conditions exposed at the time
of construction. We recommend OSHA soil type B be used to evaluate slope configurations.
However, temporary slopes greater than 10 feet high should be inclined no steeper than 1.5:1
(horizontal to vertical). After the surcharge is removed, the building pad subgrade should be
prepared in accordance with recommendations from Section 7.2.1.
7.3
Wick Drain Installation
We understand it may be desirable to install wicks to accelerate the settlement under the
proposed building pad.
We performed our settlement analyses assuming wick drains spaced four and five feet on
center in a triangular pattern; as our analysis shows about 81 percent of the settlement will
occur during a 5-month period where wick drains are spaced at 5 feet on center and around
92 percent of the settlement will occur during a 5-month period where wick drains are spaced
at 4 feet on center. We therefore recommend that wick drains be spaced in a triangular pattern
4 feet on center. The closer wick spacing will increase the rate of dissipation of excess pore
water pressures, resulting in less settlement at the end of after removing the surcharge
mound. We recommend wicks extend through the bottom of the Bay Mud.
6
Relative compaction refers to the in-place dry density of soil expressed as a percentage of the maximum dry
density of the same material, as determined by the ASTM D1557 laboratory compaction procedure.
22 June 2015
730163312
Page 16
Typically a drainage blanket is used to collect the water from the wicks. The details regarding
the drainage of the wicks should be discussed with the wicking subcontractor and reviewed by
Langan.
7.4
Seismic Design
For seismic design in accordance with the provisions of 2013 CBC, we recommend the
following:
7.5

Risk Targeted Maximum Considered Earthquake (MCER) SS and S1 of 1.684g and
0.776g, respectively.

Site Class E

Site Coefficients Fa and Fv of 0.9 and 2.4, respectively

Maximum Considered Earthquake (MCE) spectral response acceleration parameters at
short periods, SMS, and at one-second period, SM1, of 1.515g and 1.863g, respectively.

Design Earthquake (DE) spectral response acceleration parameters at short period, SDS,
and at one-second period, SD1, of 1.010g and 1.242g, respectively.
Floor Slabs
If a deep foundation system is used we recommend that floor slabs be structurally supported
and span between pile caps and grade beams, because of the large settlements that are
expected to occur. If a surcharge and wicking program is used and a shallow foundation
system is use such as a stiffened grade beam grid, then a structural slab should also be used to
help stiffen the system. The subgrade for floor slabs should be prepared in accordance with
Section 7.2.1. If the subgrade is disturbed during excavation for footings and utilities, it should
be prepared to provide firm support for casting of the slab. Loose, disturbed materials should
be excavated, removed, and replaced with engineered fill during final subgrade preparation.
Although settlement is expected to occur, the building slab will be contact with the soil with a
shallow foundation system and for a short period of time if the building is supported deep
foundations. Therefore, we recommend installing a capillary moisture break and a water vapor
retarder if water vapor moving through the slab is unacceptable or if there are finished floor
coverings susceptible to moisture. A capillary moisture break consists of at least four inches of
clean, free-draining gravel or crushed rock. The vapor retarder should meet the requirements
for Class C vapor retarders stated in ASTM E1745-97. The vapor retarder should be placed in
accordance with the requirements of ASTM E1643-98.
These requirements include
overlapping seams by six inches, taping seams, and sealing penetrations in the vapor retarder.
22 June 2015
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Page 17
The vapor retarder should be covered with two inches of sand to aid in curing the concrete and
to protect the vapor retarder during slab construction. The particle size of the gravel/crushed
rock and sand should meet the gradation requirements presented in Table 7.
TABLE 7
Gradation Requirements for Capillary Moisture Break
Sieve Size
Percentage Passing Sieve
Gravel or Crushed Rock
1 inch
90 – 100
3/4 inch
30 – 100
1/2 inch
5 – 25
3/8 inch
0–6
Sand
No. 4
100
No. 200
0–5
The sand overlying the membrane should be moist at the time concrete is placed; however,
there should be no free water in the sand. Excess water trapped in the sand could eventually
be transmitted as vapor through the slab. If rain is forecast prior to pouring the slab, the sand
should be covered with plastic sheeting to avoid wetting. If the sand becomes wet, concrete
should not be placed until the sand has been dried or replaced.
Concrete mixes with high water/cement (w/c) ratios result in excess water in the concrete,
which increases the cure time and results in excessive vapor transmission through the slab.
Therefore, concrete for the floor slab should have a low w/c ratio - less than 0.50. If approved
by the project structural engineer, the sand can be eliminated and the concrete can be placed
directly over the vapor retarder, provided the w/c ratio of the concrete does not exceed 0.45
and water is not added in the field. If necessary, workability should be increased by adding
plasticizers. In addition, the slab should be properly cured.
Before the floor covering is placed, the contractor should check that the concrete surface and
the moisture emission levels (if emission testing is required) meet the manufacturer’s
requirements.
7.6
22 June 2015
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Page 18
Underground Utilities
Utility trenches should be excavated a minimum of four inches below the bottom of pipes or
conduits and have clearances of at least four inches on both sides. Where necessary, trench
excavations should be shored and braced to prevent cave-ins and/or in accordance with all
safety regulations. Where trenches extend below the groundwater level, it will be necessary to
temporarily dewater them to allow for placement of the pipe and/or conduits, and backfill.
To provide uniform support, pipes or conduits should be bedded on a minimum of four inches
of sand or fine gravel.
After pipes and conduits are tested, inspected (if required), and
approved, they should be covered to a depth of six inches with sand or fine gravel, which
should then be mechanically tamped. Backfill should be placed in lifts of eight inches or less,
moisture-conditioned, and compacted to at least 90 percent relative compaction except in
pavement areas where the upper 6 inches should be compacted to 95 percent.
Backfill in utility trenches can consist of either on-site material or approved imported fill. Bay
Mud may be reused as fill provided it is properly moisture conditioned and placed below
Elevation 100 feet. Backfill should be compacted according to the preceding recommendations
for fill in Section 7.2.1. Locally, flexible utility connections may be needed to accommodate up
to several inches of vertical ground settlement.
8.0
ADDITIONAL GEOTECHNICAL SERVICES
We should review the project plans and specifications to check their conformance with the
intent of our recommendations.
During construction, we should observe site preparation,
placement and compaction of fill, and installation of building foundations. These observations
will allow us to compare the actual with the anticipated subsurface conditions and to check that
the contractor's work conforms to the geotechnical aspects of the plans and specifications.
9.0
LIMITATIONS
The conclusions and recommendations presented in this report result from limited engineering
studies and are based on our interpretation of the geotechnical conditions existing at the site at
the time of investigation.
Actual subsurface conditions may vary.
If any variations or
undesirable conditions are encountered during construction, or if the proposed construction will
differ from that described in this report, Langan Treadwell Rollo, Inc. should be notified to make
supplemental recommendations, as necessary.
REFERENCES
California Building Code (2013).
California Division of Mines and Geology, 2001, “State of California Special Studies Zones, City
and County of San Francisco Quadrangle Official Map,” 17 November 2001.
California Geological Survey (2008). “Guidelines for Evaluating and Mitigating Seismic Hazards
in California.” Special Publication 117A.
Cao, T., Bryant, W. A., Rowshandel, B., Branum D. and Wills, C. J. (2003). “The Revised 2002
California Probabilistic Seismic Hazard Maps.”
Lee & Praszker (1985). “Geotechnical Investigation, Marine World Executive Office Park,
Redwood City, California.”
Lienkaemper, J. J. (1992). “Map of Recently Active Traces of the Hayward Fault, Alameda and
Contra Costa counties, California.” Miscellaneous Field Studies Map MF-2196.
Seed, R. B. et al. (2003). “Recent Advances in Soil Liquefaction Engineering: A Unified and
Consistent Framework.” 26th Annual ASCE Los Angeles Geotechnical Seminar, Long Beach,
California, 30 April.
Treadwell & Rollo, Inc. (2001). “Environmental Site Characterization, Proposed Oracle Child
Care Center, Redwood City, California.” Project Number 1633.11.
Treadwell & Rollo, Inc. (2002). “Geotechnical Study, Oracle Child Care Center, Site Number 2,
Redwood City, California.” Project Number 1633.11.
Toppozada, T. R. and Borchardt G. (1998). “Re-Evaluation of the 1836 “Hayward Fault” and the
1838 San Andreas Fault earthquakes.” Bulletin of Seismological Society of America, 88(1), 140159.
Townley, S. D. and Allen, M. W. (1939). “Descriptive Catalog of Earthquakes of the Pacific
Coast of the United States 1769 to 1928.” Bulletin of the Seismological Society of America,
29(1).
Wesnousky, S. G. (1986). “Earthquakes, Quaternary Faults, and Seismic Hazards in California.”
Journal of Geophysical Research, 91 (1312).
Working Group on California Earthquake Probabilities (WGCEP) (2007). “The Uniform California
Earthquake Rupture Forecast, Version 2.” Open File Report 2007-1437.
Youd, T. L. and Garris, C. T., (1995) “Liquefaction-Induced Ground-Surface Disruption,” Journal
of Geotechnical Engineering, 121(11), 805 – 809.
Youd, T. L. and Idriss, I. M., (2001), “Liquefaction Resistance of Soils: Summary Report from
the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of
Soils,” Journal of Geotechnical and Geoenvironmental Engineering, 127(4), 297 – 313.
Youd, L. T. and Carter, B. L. (2005), “Influence of Soil Softening and Liquefaction on Spectral
Acceleration,” Journal of Geotechnical and Geoenvironmental Engineering, 131(7), 811-825.
FIGURES
SITE
0
1000
2000 Feet
Approximate scale
ORACLE EDUCATION FACILITY
SITE LOCATION MAP
Date 06/19/15 Project No. 730163312 Figure 1
EXPLANATION
SB-9
SB-11
SB-7
SB-1
Approximate location of boring by Treadwell & Rollo,
Inc., March 2001
TB-8
Approximate location of boring by Lee & Praszker,
1985
SB-5
SB-4
SB-12
SB-10
SB-8
SB-6
SB-2
TB-8
TB-9
SB-3
SB-1
PROPOSED BUILDING FOOTPRINT
TB-10
TB-11
TB-12
SITE PLAN
0
Reference: Base map from a drawing titled "Oracle Educational Facility" by BKF, dated 6/8/2015.
100 Feet
Approximate scale
Date 06/22/15
Project No. 730163312 Figure 2
i
om
ay
Sutter
Placer
3
El Dorado
Yolo
y
alle
at V
Gre
lle
vi
er
rb
Ga
a-
a
ess
rry
Be
ekCre
ng
nti
Hu
m
ca
aa
M
Lake
y
alle
at V
Gre
ll
Co
Mendocino
4a
nd
nA
Sa
Napa
Sonoma
Grea t
s
rea
Sacramento
ley
Val
4b
a
Nap
k
ee
Cr
t
Wes
ers
dg
Ro
Amador
Solano
y
alle
at V
Gre
Green
in
Po
Calaveras
5
es
ey
y
Valle
tR
Marin
n
Sa
Contra
Costa
An
dr
s
ea
M
ou
nt
SITE
Di
Th
r
d
ill e
nv
ee
Gr
ar
yw
Ha
San
Francisco
ab
lo
San
Joaquin
us
t
nn
Co
ted
ec
PA C I F I C
Alameda
OCEAN
Stanislaus
Great
Valley 8
nne
Co
ta
-S
ha
s
o r io
Vi
s
ra
ve
reg
M
on
te
ala
lC
ta
To
G
San
San
Mateo
nn
on
cte
d
Santa
Cruz
Magnitude 6 to 6.9
n
a
e
rg
Ve
e-
be
Sa
San
Benito
Monterey
ien
Qu
s
le
County Boundary
A
dr
Za
ea
ya
s
nt
y s
re
te cito
on r
M Tula
yBa
Fault
Sa
n
t
ali
ti g
Or
Magnitude 7 to 7.4
Magnitude 7.5 to 8
Merced
Santa
Clara
Magnitude 5 to 5.9
Great
Valley
9
Earthquake Epicenter
Fresno
Notes:
1. Quaternary fault data displayed are based on a generalized version of U.S. Geological
Survey (USGS) Quaternary Fault and fold database, 2010. For cartographic purposes only.
2. The Earthquake Epicenter (Magnitude) data is provided by the USGS and is current
through 08/24/2014.
0
3. Basemap hillshade and County boundaries provided by USGS and California
Department of Transportation.
4. Map displayed in California State Coordinate System, California (Teale) Albers,
North American Datum of 1983 (NAD83), Meters.
10
20
40
Miles
q
MAP OF MAJOR FAULTS AND
EARTHQUAKE EPICENTERS IN
THE SAN FRANCISCO BAY AREA
Date 06/19/15
Project No. 730163312
Figure
3
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
Not felt by people, except under especially favorable circumstances. However, dizziness or nausea may be experienced.
Sometimes birds and animals are uneasy or disturbed. Trees, structures, liquids, bodies of water may sway gently, and doors may swing
very slowly.
Felt indoors by a few people, especially on upper floors of multi-story buildings, and by sensitive or nervous persons.
As in Grade I, birds and animals are disturbed, and trees, structures, liquids and bodies of water may sway. Hanging objects swing,
especially if they are delicately suspended.
Felt indoors by several people, usually as a rapid vibration that may not be recognized as an earthquake at first. Vibration is similar
to that of a light, or lightly loaded trucks, or heavy trucks some distance away. Duration may be estimated in some cases.
Movements may be appreciable on upper levels of tall structures. Standing motor cars may rock slightly.
Felt indoors by many, outdoors by a few. Awakens a few individuals, particularly light sleepers, but frightens no one except those
apprehensive from previous experience. Vibration like that due to passing of heavy, or heavily loaded trucks. Sensation like a heavy
body striking building, or the falling of heavy objects inside.
Dishes, windows and doors rattle; glassware and crockery clink and clash. Walls and house frames creak, especially if intensity is in the
upper range of this grade. Hanging objects often swing. Liquids in open vessels are disturbed slightly. Stationary automobiles rock
noticeably.
Felt indoors by practically everyone, outdoors by most people. Direction can often be estimated by those outdoors. Awakens many,
or most sleepers. Frightens a few people, with slight excitement; some persons run outdoors.
Buildings tremble throughout. Dishes and glassware break to some extent. Windows crack in some cases, but not generally. Vases and
small or unstable objects overturn in many instances, and a few fall. Hanging objects and doors swing generally or considerably.
Pictures knock against walls, or swing out of place. Doors and shutters open or close abruptly. Pendulum clocks stop, or run fast or slow.
Small objects move, and furnishings may shift to a slight extent. Small amounts of liquids spill from well-filled open containers. Trees and
bushes shake slightly.
Felt by everyone, indoors and outdoors. Awakens all sleepers. Frightens many people; general excitement, and some persons run
outdoors.
Persons move unsteadily. Trees and bushes shake slightly to moderately. Liquids are set in strong motion. Small bells in churches and
schools ring. Poorly built buildings may be damaged. Plaster falls in small amounts. Other plaster cracks somewhat. Many dishes and
glasses, and a few windows break. Knickknacks, books and pictures fall. Furniture overturns in many instances. Heavy furnishings
move.
Frightens everyone. General alarm, and everyone runs outdoors.
People find it difficult to stand. Persons driving cars notice shaking. Trees and bushes shake moderately to strongly. Waves form on
ponds, lakes and streams. Water is muddied. Gravel or sand stream banks cave in. Large church bells ring. Suspended objects quiver.
Damage is negligible in buildings of good design and construction; slight to moderate in well-built ordinary buildings; considerable in
poorly built or badly designed buildings, adobe houses, old walls (especially where laid up without mortar), spires, etc. Plaster and some
stucco fall. Many windows and some furniture break. Loosened brickwork and tiles shake down. Weak chimneys break at the roofline.
Cornices fall from towers and high buildings. Bricks and stones are dislodged. Heavy furniture overturns. Concrete irrigation ditches are
considerably damaged.
General fright, and alarm approaches panic.
Persons driving cars are disturbed. Trees shake strongly, and branches and trunks break off (especially palm trees). Sand and mud
erupts in small amounts. Flow of springs and wells is temporarily and sometimes permanently changed. Dry wells renew flow.
Temperatures of spring and well waters varies. Damage slight in brick structures built especially to withstand earthquakes; considerable
in ordinary substantial buildings, with some partial collapse; heavy in some wooden houses, with some tumbling down. Panel walls
break away in frame structures. Decayed pilings break off. Walls fall. Solid stone walls crack and break seriously. Wet grounds and steep
slopes crack to some extent. Chimneys, columns, monuments and factory stacks and towers twist and fall. Very heavy furniture moves
conspicuously or overturns.
Panic is general.
Ground cracks conspicuously. Damage is considerable in masonry structures built especially to withstand earthquakes; great in other
masonry buildings - some collapse in large part. Some wood frame houses built especially to withstand earthquakes are thrown out of
plumb, others are shifted wholly off foundations. Reservoirs are seriously damaged and underground pipes sometimes break.
Panic is general.
Ground, especially when loose and wet, cracks up to widths of several inches; fissures up to a yard in width run parallel to canal and
stream banks. Landsliding is considerable from river banks and steep coasts. Sand and mud shifts horizontally on beaches and flat
land. Water level changes in wells. Water is thrown on banks of canals, lakes, rivers, etc. Dams, dikes, embankments are seriously
damaged. Well-built wooden structures and bridges are severely damaged, and some collapse. Dangerous cracks develop in excellent
brick walls. Most masonry and frame structures, and their foundations are destroyed. Railroad rails bend slightly. Pipe lines buried in
earth tear apart or are crushed endwise. Open cracks and broad wavy folds open in cement pavements and asphalt road surfaces.
Panic is general.
Disturbances in ground are many and widespread, varying with the ground material. Broad fissures, earth slumps, and land slips
develop in soft, wet ground. Water charged with sand and mud is ejected in large amounts. Sea waves of significant magnitude may
develop. Damage is severe to wood frame structures, especially near shock centers, great to dams, dikes and embankments, even at
long distances. Few if any masonry structures remain standing. Supporting piers or pillars of large, well-built bridges are wrecked.
Wooden bridges that "give" are less affected. Railroad rails bend greatly and some thrust endwise. Pipe lines buried in earth are put
completely out of service.
Panic is general.
Damage is total, and practically all works of construction are damaged greatly or destroyed. Disturbances in the ground are great and
varied, and numerous shearing cracks develop. Landslides, rock falls, and slumps in river banks are numerous and extensive. Large
rock masses are wrenched loose and torn off. Fault slips develop in firm rock, and horizontal and vertical offset displacements are
notable. Water channels, both surface and underground, are disturbed and modified greatly. Lakes are dammed, new waterfalls are
produced, rivers are deflected, etc. Surface waves are seen on ground surfaces. Lines of sight and level are distorted. Objects are
thrown upward into the air.
MODIFIED MERCALLI INTENSITY SCALE
Date 06/19/15 Project No. 730163312 Figure 4
APPENDIX A
BORING LOGS
APPENDIX B
SOIL CORROSIVITY TEST RESULTS
DISTRIBUTION
Electronic Copies to:
QUALITY CONTROL REVIEWER:
Richard D. Rodgers, G.E.
Managing Principal
Oracle

UPDATED GEOTECHNICAL STUDY Oracle

Transcription

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