History, Art and Engineering

Transcription

COVER_UKA5_tr 23-01-2015 12:08 Pagina 2
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Introduction
You don't often come across a thesis whose subject is humanistic but whose focus
is technical, namely the history of foundation technologies, as it is a topic more
commonly discussed in the corridors of engineering faculties.
The Trevi Group Academy, whose key objective is to further knowledge of foundation
technologies, jumped at the chance to support a work dealing with a “history” of this
kind.
The opportunity presented itself thanks to Giulia, whose essay gives a true insight
into our world and whose point of view and language are deliberately free of the
technical references and jargon so typical of our sector. We believe this work will
appeal to a wide audience, not just those who are already familiar with the subject.
The tone is that of a fast-paced narrative and it flows easily, giving a glimpse of the
commitment of the Trevi Group staff to develop technologies and apply them in a
vast range of projects: from foundation work in the true sense of the word, to the
preservation of historical and artistic treasures.
And it is in this last field that the work becomes even more fascinating.
Two case histories, two symbols of the history and culture of mankind, one (the Tower
of Pisa) linked to the Western world and the other (the Buddhas of Bamiyan) to the
East, are testimony of the synergy between technological innovation and the protection
of our cultural and artistic heritage. The objective here is to preserve two sites on the
List of World Heritage in Danger.
Alessandra Trevisani
Academy Director
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Table of Contents
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Chap.1. Ground Engineering: Our (Hi)story
5
Chap. 2. Engineering, Foundations, Art:
Stories from the Past
7
Chap. 3. The Trevi Group and Soilmec S.p.A.:
a Success Built on Solid Foundations
35
Chap. 4. History, Art and Engineering:
the Trevi Group's Main Restoration Projects
47
4.1 The restoration of the
Leaning Tower of Pisa
50
4.2 The Buddhas of Bamiyan
60
Chap. 5. In conclusion
67
Chap. 6. References and Websites
68
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1.
Chap.
Ground Engineering:
Our (Hi)story
If you let your mind wander over human history, you will probably realize that one
of the main aspects of life that attracted early human efforts was the construction
of buildings. After the caveman era, men struggled to improve their building skills,
erecting houses and structures using more and more sophisticated materials to
ensure their stability and safety. Over history, materials have ranged from straw to
stone, to reinforced concrete in most recent times. With the creation of villages,
towns and cities, the concept of “building” has extended to our present elaborate
structures. This web of buildings is where we conduct our everyday lives. Good
building skills mean concern for safety, stability and a quality environment. This
issue has been crucial since the most ancient times: the Roman architect Vitruvius
claimed that firmitas (firmness), utilitas (utility) and venustas (delight) are essential
qualities to a structure. In his famous De Architectura, Vitruvius stated: “All structures
must be built with due reference to durability (firmness), convenience (utility), and
beauty (delight). Durability will be assured when foundations are carried down to the
solid ground and materials wisely selected from a wide range of sources; convenience,
when the arrangement of the apartments is faultless and presents no hindrance to
use, and when each class of building is assigned to its suitable and appropriate
exposure; and beauty, when the appearance of the work is pleasing and in good
taste, and when its components are in due proportion according to correct principles
of symmetry”.
Now, let us focus on foundations, which are key structures both in architecture and
in the building industry. Their name speaks for itself: “foundations” are the basis we
build upon. Not only does this concept concern buildings, as in this case, but it also
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extends to any kind of project, or even the development of an idea. Nothing can be
constructed without perfectly designed and stable foundations. Throughout history,
engineering, architecture and technology have substantially contributed to the
development of safer and more stable foundations. How have we achieved such
excellent results?
In 2012, the Trevi Group, international leader in the ground engineering industry, and
Soilmec S.p.A., its mechanical division, shattered a record by excavating a slurrytrench panel 250 meters underground. A long journey, starting many centuries ago,
led to this achievement, and the Trevi Group has taken the most recent and significant
steps on this path. Follow us in this journey back in time, recalling the historical
periods and the thousands of people that have contributed to writing a chapter of
this story. Its most remarkable chapters are still right here, in front of your eyes (and
Gualdo’s Test Field - Gualdo di Roncofreddo (FC) Italy
-250 m “World Drilling Record”
below your feet).
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2.
Chap.
Engineering, Foundations, Art:
Stories from the Past
This story begins in 2980 B.C., when the Egyptian architect Imhotep was appointed
by King Djoser to build a special type of tomb called a mastaba to show the world
the power of the king. No one could have known at the time, but this was a turning
point in history: King Djoser's tomb of Saqqara was the earliest large-scale cut stone
construction ever built. Standing 59.94 meters high, it consisted of layers of limestone
of decreasing size, built on top of one another. The only available means for workers
for smoothing the limestone blocks must have been mere pickaxes. Since tools for
the lifting and carrying of rough materials did not exist, a significant amount of
manpower was needed to physically carry around sand and stones, with the aid of
baskets or temporary ramps. A few tools and a lot of sweat and labor were the only
means available at the time.
Imhotep was thus the first architect in history to build a stone construction. However,
in 2570 B.C., the architect Hemiunu also marked a turning point in
building history when he designed a tomb for pharaoh Khufu,
in the Egyptian town of Giza. This gigantic and internationally
reputed construction is the Great Pyramid, one of the
Seven Wonders of the Ancient World. A height of 146.6
meters, one hundred thousand workers, twenty years
of work: these numbers are even more staggering if you
consider that workers physically carried around the heavy
limestone which this amazing pyramid is made of. The
builder-in-chief chose to build it upon the Giza Plateau for a
very specific reason: since many monumental tombs had collapsed
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before because of the soft ground, the firm limestone soil of the site could not be a
more appropriate base for the pyramid. The choice of the right spot and the smoothing
of the soil allowed this gigantic structure to stand the test of time.
From the 16th century B.C., Greece became the most prominent hive of ideas and
innovations in the engineering industry. The figure of the Egyptian builder-in-chief
was replaced by the Greek architekton (“master builder”), applying the principles
of early engineering science to the managing of manpower. Modern engineering
science, which would ultimately simplify and improve our daily (and working) lives,
was taking shape. The first port in history, on the island of Samos, was built focusing
on functionality. Since it facilitated maritime trade activities, it became a model for
many other ports. Meanwhile, extraction and mine building techniques were developed
and astonishingly deep wells (as deep as 115 meters underground) were built in
Laurium for the extraction of minerals. This was a particularly tough challenge if you
consider that the stony soil could only be removed with the aid of pickaxes and
chisels. Around the middle of the 3rd century B.C., Archimedes conceived the screw
pump, also called “Archimedes' screw”, for draining land underneath the sea.
Archimedes' screw is still used today for rural and irrigation activities. In fact, though
the ancient engineers did not have as much scientific knowledge as we have today,
some of their “ideas” are still in use and bear evidence of remarkable foresight,
combined with a touch of luck.
After 31 B.C., during the Roman empire, the combination of lime and volcanic dust
led to the creation of hydraulic cement, which hardens when combined with water.
Aqueducts and bridges were indeed the most important structures of this period.
For instance, the most famous Roman builder Appius Claudius (who also built the
Via Appia) built the Roman aqueduct called Aqua Appia under the Romans. In 15
B.C, Vitruvius wrote the aforementioned milestone book De Architectura, describing
engineering development. Vitriuvius explained the design of Roman bridge foundations
- for example, the remarkable Milvian Bridge of Rome, built in 109 B.C., which has
been bearing all kinds of weights throughout the centuries. Workers used ropes to
lift piles of specific dimensions and used pumps to drain water, replacing it with such
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materials as mortar or sand. Then, they drove piles into oak cofferdams secured to
the ground and surrounded them with stones in order to ensure the longevity and
stability of the structure. The Romans also invented the arch, improving the firmness
of bridges, and aqueducts and theaters as well. The arch bears heavier weights by
exploiting the pressure of the stones upon each other, while the traditional monolith
is more likely to collapse. The qualities of the arch are exemplified by the Ponte Pietra
(Italian for “stone bridge”), the only Roman bridge still standing in Verona, Italy.
Cathedrals and fortified castles flourished during the Middle Ages, from the 5th to
the 15th century. It might be interesting to note that the colossal and magnificent
cathedrals of this period were often built on poor soil. Foundations would not be laid
deep into the ground, making it more difficult to bear the weight of those huge
structures. This might be one of the reasons for the inclination of the Tower of Pisa,
built in the middle of that period, in 1174. We will describe this particular case later
on. However, the construction of some other cathedrals was definitely more successful.
In The Cathedral Builders, the French historian Jean Gimpel stated: “the foundations
of the cathedrals are laid as deep as 10 meters (the average depth of a Paris
underground station) and in some cases there is as much stone below ground as
can be seen above”. Many Gothic cathedrals have endured wars and natural
phenomena, reaching outstanding heights in a mixture of beauty and technique. The
Cathedral Basilica of Saint-Denis, built in 1136 in a suburb of Paris, is an excellent
example as it is one of the first truly Gothic buildings.
Just like cathedrals, fortified castles also flourished during the medieval period.
Architects preferred stones to build castles on promontories, where visibility is
maximized. These castles provided further military protection against catapults, for
peasants and especially aristocrats. The 20 meter-deep ditch and double doors of
the French Château de Coucy made it an impregnable castle. Its donjon, standing
over 55 meters, is still the highest one in Europe and served as a shelter for the
landlord in the event of an attack.
Between the 15th and the 17th century, a combination of architectural techniques,
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Archimede di Siracusa
(Syracuse, c. 287 BC - c.212 BC) was an Ancient Greek mathematician, physicist, engineer,
inventor, and astronomer. Generally considered the greatest mathematician of antiquity
and one of the greatest of all time, the contributions of Archimedes ranges from geometry
to hydrostatics, from optics to mechanics.
In 235 BC during a trip to Egypt he invent the Archimedean screw, also called screwpump, is a machine used for transferring water from a low-lying body of water into irrigation
ditches. Until this moment the irrigation water was being raised from ditches into fields
by hand-lifted buckets, a slow and hard method. Archimedes' screw consists of a screw
(an inclined surface wrapped around a central post or pillar) inside a hollow pipe. The
screw is turned usually by a windmill or by manual labour. As the shaft turns, the bottom
end scoops up a volume of water. This water will slide up in the spiral tube, until it finally
pours out from the top of the tube and feeds the irrigation systems.
Today the Archimedean screw was replaced by water wheels and powered
pumps but the principle of Archimedes invention had lasting value and the
main concept, use the screw to lift a liquid or a granular m a t e r i a l
(sand, gravel or crushed solid), was extended to various
modern application. In the foundation technology field was
developed a method for large diameter piles construction
named CAP.
Cased Auger Piles (CAP) are performed by means
of a continuous flight auger housed inside a steel
casing. During drilling phase the excavated material
is loaded onto the flight to be transported to the top
of the casing, exploiting the Archimedean screw
principle, to be discharged on ground through a Spoil
Chute. Reached the required depth the auger and
the casing are extracted while the concrete is poured
throughout the internal hollow pipe. Finally if required,
the steel reinforcement (cages, profiles or beams)
is lowered into the fresh concrete.
Rif. Bibliografici: 100 Greatest Science Inventions of All Time; Di Kendall F. Haven
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Soilmec’s drilling equipment
includes a wide range of models
characterized by the CAP/CSP
technology, such as the
SR-100 reaching a maximum
depth of 28 metres.
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engineering science and the aesthetic “whims” of art was taking shape. During this
period, the architect Filippo Brunelleschi designed the Basilica of Saint Mary of the
Flower (Florence, Italy), while further historically remarkable bridges were being built.
However, foundation techniques were still far from perfect. For example, placing
piles for the foundations of the Rialto Bridge in Venice, completed in 1591 by the
architect Antonio da Ponte, was a tough challenge: the ground was too marshy and
soft. The architect Vincenzo Scamozzi even claimed that the bridge could collapse
at any moment. Although the Rialto Bridge is still standing today, time and use have
caused minor collapses during the last few years - the last one, in 2011, involving
one of the columns. Too little knowledge about foundation techniques also caused
several problems during the construction of cofferdams for the foundations of the
Pont Neuf, in Paris. Dating back to the 16th century, it is the oldest standing bridge
across the River Seine. Even though engineers prepared wooden models of cofferdams,
the water flow pressure and the lack of piles made the bridge so unstable that the
foundations had to be repaired before being completed. However, the Pont Royal,
built between 1685 and 1689, represents an example of extraordinary bridge
construction, where open caisson foundations were installed for the first time. The
top of the open, watertight cofferdams was left above the water surface and piles,
embedded into the cofferdams, were surrounded by a group of tubes. The bridge
remained so stable that its designer, the Dominican priest and designer François
Romain, gained much popularity among the engineers of the time.
During that same period, another remarkable French structure was being completed.
Louis XIV had demanded the construction of the Canal du Midi to boost and speed
up trade without passing through the Straits of Gibraltar. This 240-km-long canal
connects the Atlantic Ocean to the Mediterranean. At first, it seemed such an
impossible task that its complex design was refused by several designers but,
eventually, engineer Jean-Paul Riquet developed and successfully completed the
project. Today, the Canal du Midi has several dams and over 100 locks, measuring
30 meters in length and 5.8 meters in width.
During the 18th century, foundation theory and techniques were being developed.
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For the first time, the engineer Hubert Gautier described mechanical engineering
applied to bridge construction in his Treatise on Bridges (1716). In this treatise,
Gautier illustrated the history of bridge construction techniques and materials until
his time, dedicating an entire chapter to foundations, discussing the best dimensions
for piles and arches and describing his own on-site experiences. Gautier argues that
there as many types of foundations as there are types of soil and structures that can
be built, and encourages designers to always be careful, go on-site to carry out indepth investigations and be collaborative with workers. He eventually affirms that:
“when preparing a project, designers should follow a precise chronological order,
just as if they had to build the structure with their own hands. Bridge engineering is
one of the most difficult matters, therefore they must be particularly careful. In order
to evaluate a project objectively, everything should be clear. Excess and extravagance
should be left apart and problems should be highlighted, especially as far as
foundations are concerned”. This is the first detailed book that we have on the
preparation of foundations.
During the 18th century, an Italian engineer called Jean-Baptiste de Voglie marked
a turning point in the history of foundation engineering. In 1753, during the construction
of the foundations of the bridge of Saumur, France, for the first time he laid caissons
instead of cofferdams. Caissons are used when excavating and preparing foundations
under the water surface: the air is pumped until reaching a pressure higher than that
of the weight of the water and, when pumped air drains the water, the installation
of foundations can begin. Workers go back to the surface by slow decompression,
just as divers do. Although it is a complex procedure, it has been effective for
centuries. For example, the foundations of the Westminster Bridge were prepared
by installing a caisson into the excavated ground under the River Thames: workers
placed a stone pile into the caisson only after draining the water inside.
However, foundations were neither deep nor durable. To make sure that foundations
remained stable while laying the caisson, De Voglie instructed that the tubes be cut
directly under the water of the Saumur with a special waterproof saw. Foundations
could thus be laid in the deepest point in the ground ever reached - at least until
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1811, when the French engineer Claude
Deschamps used the same method to
install caissons 4 meters underground.
During the 19th century, the laying of
caissons became a commonly used
method when preparing underwater
foundations. Progress in technology
allowed for the development and
improvement of their composition and,
in 1839, another French engineer called
Jacques Triger used compressed-air
caissons (or pneumatic caissons) for the
first time to lay foundations under the
water. This type of caisson allows
foundations to be laid deeper
underground than the more traditional
cofferdam. Workers use a compression
and decompression chamber to go inside
the caisson and dig in smaller and smaller
areas of the soil. When workers go back to the surface, the lack of pressure pushes
the caisson downwards. The digging continues when the pressure level is raised,
and so forth. For the first time, caissons were made of concrete.
In the meantime, the American engineer James Finley patented a type of bridge that
would serve as a model for projects in the United States and in the rest of the world.
In fact, he had invented the suspension bridge, a particular kind of structure that
bears heavy weights, railways included. The pedestrian part of the bridge is supported
by a system of rigid cables secured to structures built on piles or to cables at the
two ends of the bridge. Finley built the first suspension bridge in Pennsylvania, in
1801: it was the Jacob's Creek Bridge - which, unfortunately, was demolished 30
years later. Finley's dream was to build a low-maintenance structure, which would
not require expensive construction materials and would be simple enough to serve
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as a model for other bridges and other projects. He achieved his goal by using
inexpensive, long-lasting forged steel cables, which served a dual purpose. On the
one hand, they made the bridge deck - the roadway surface of the bridge - so flexible
that it could bear heavy weights. On the other hand, they made the bridge rigid
enough to prevent it from bending even with strong winds.
In 1869, a German engineer living in the U.S. designed another, more famous
suspension bridge and made his fortune with this type of structure. In fact, John
Roebling designed the Brooklyn Bridge, connecting the boroughs of Manhattan
and Brooklyn in New York. Unfortunately, he died soon after the beginning of the
construction and his son Washington Roebling took his place.
First, workers
prepared the
84-meter-high
towers which
the
would
cables
be
anchored to:
foundations
therefore had
to be laid
particularly
deep into the
ground. They
built a wooden
caisson and a
steel caisson
for each tower. Compressed-air caissons were used to dig into the soil, while slowly
placing the caisson. No one was aware of the consequences that changes in pressure
could have on health: workers going inside the caissons ended up suffering from
serious physical diseases, and Washington Roebling, who regularly supervised the
construction, soon got ill. Construction work continued anyway, until completion.
When Washington became unable to supervise the construction, it was a woman
who took his place: his wife Emily.
The granite towers were built in a Gothic style that combined functionality and
aesthetics. Eventually, workers prepared four, 5,000-meter-long cables and secured
them to the anchorages on the bridge towers. The main structure was made of steel
girders attached to wires. Completed in 1883, the Brooklyn Bridge has a span of
almost 2 kilometers and has long been the longest suspension bridge in the world.
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It was a masterpiece of bridge foundation engineering of the time and was the
very first time that compressed-air caissons were used for a large-scale structure,
with such modern and resistant materials.
It is not a widely known fact, but during that same period an unknown French engineer
was getting more and more attention and gaining expertise in the engineering of
metal structures. He had supervised the construction of the iron bridge in Bordeaux,
France, at the age of only 26, and he had set up his own workshops, creating all
sorts of metalwork. But he would gain outstanding visibility only in 1889, in the event
of the Universal Exposition in Paris. It was Gustave Eiffel, who is considered the
father of metal constructions and who designed the famous Eiffel Tower, which
became a symbol of the Ville Lumière. The Eiffel Tower took only two years to build
and is still the highest building in Paris. Its construction was definitely not an easy
challenge. The numbers speak for themselves: 18,038 metal pieces, 300 on-site
employees, 50 engineers, 2,500,000 iron rivets. The foundations of the Eiffel Tower
are its pièce de résistance, even though they took only 5 months to build. Eiffel
carried out preparatory drills to test whether the ground could bear the weight of the
structure. The soil of Champ de Mars was composed of a layer of clay covered by
a layer of sand and gravel of different dimensions. It was ideal for laying good
foundations. When compressed-air caissons had been prepared and filled with
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John Roebling
(Muhlhausen, (June 12, 1806 - July 22, 1869)
John Roebling (June 12, 1806 - July 22, 1869) was a German-born American civil engineer.
He settles in the United States in 1831 and he started working as engineer in the State
administration. He works on roads and canals, and from this experience decides in 1841
to create a small factory that twist steel wire into cables. His engineering activity begins
in 1844 and became famous for his wire rope suspension bridge designs and especially
for the Brooklyn Bridge.
The single greatest wonderment of the Brooklyn Bridge is not its size, beauty, function
or even technology, but the fact that it was created by hand. Roebling used innovative
techniques such as erecting towers with a pneumatic caisson method and anchorages
for securing the wire cables. Caissons are large wooden boxes that serve as the foundation
for the bridge's two towers. The caissons were filled with compressed air when the
workers entered them. Inside the air lock of the caissons,
workers dug out the mud from underneath
the river until they reached solid
bedrock. From
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here, the caissons were filled with concrete and the foundation was completed for the
towers. Despite the goodness of the method the compressed air in these caissons may
result in health damage so that his son Washington, who conducted work after the death
of John, was partially paralyzed cause of decompression sickness. "Inside the caisson
everything wore an unreal, weird appearance. There was a confused sensation in the
head, like the rush of many waters. The pulse was at first accelerated, then sometimes
fell below the normal rate. The voice sounded faint unnatural, and it became a great effort
to speak. What with the flaming lights, the deep shadows, the confusing noise of hammers,
drills and chains, the half-naked forms flitting about, if of a poetic temperament, get a
realizing sense of Dante's inferno. One thing to me was noticeable - time passed quickly
in the caisson." - E.F. Farrington, mechanic for the Brooklyn Bridge
With the growth of drilling machines also the foundation techniques of major works in
water were strongly evolved towards the use of bored piles. The most commonly used
technique for pile boring is with Kelly bar and permanent steel casing by using drilling
rig mounted on pontoons, or spuds driven into the seabed, depending on a head of water.
The Vasco da Gama Bridge is one of the most important infrastructural projects on water
carried out in Europe. The bridge, with its 18 Km of extension, develops along viaducts
for about one third of its whole length completing the road system that surrounds Lisbon
city and represents an important junction for the crossing of Portugal and Spain, along
the North-South direction. The foundations adopted for viaducts were of two types large
diameter bored piles and steel driven piles ranging from 800 to 2200 mm diameter
to a depth of 79 m executed from pontoons designed to satisfy all different requirements
in terms of production phases and various tasks in a safe job site.
The Vasco da Gama bridge in figures:
148
124
3
16400
80000
Bored Piles Ø 2200 mm
Bored Piles Ø 2000 mm
Load testing on bored piles on water
Steel Sheet Piles
Dredging
110
3450
11300
6700
5200
Driven Piles
Deck Surface
Underwater laying of geotextiles
Underwater laying of concrete
Steel pipes construction
Rif.Bibliografici:
DESIGN AND DESIGNERS by Michel Virlogeux
www.brooklynbridgeaworldwonder.com
Vasco da Gama bridge by Trevi Spa
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concrete, they were set only 15 meters deep into the ground, even though the weight
of the structure was expected to be significant. Once foundations had been completed,
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pieces were assembled using a timber
scaffold. In the record time of 21 months considering the limited resources available
during that period - the tower was
completed. Standing around 304 meters
high (without the antenna spire), the Eiffel
Tower was criticized by several artists at
the time of its construction and it still is by
some Parisians. Yet it has inevitably become
a symbol of French architecture for people
around the world. Furthermore, it held the
record of the tallest building in the world
until 1930, when the Empire State Building
was constructed in New York (381 meters
high). Maintenance is its main problem:
every piece must be checked and painted daily throughout the year in order to
prevent the ironwork from rusting.
By then, the pneumatic caisson technique was a well-established practice. Four
years after the construction of the Eiffel Tower, in 1893, this procedure was used for
the first time to lay foundations for an apartment building: the Empire State Building
in New York. Its architects, Kimball and Thompson, were among the first in Manhattan
to use the steel frame technique, which allows for the construction of taller buildings.
Today, the Empire State Building is still considered one of the most beautiful buildings
in New York for its flawless, neoclassical architecture. Architecture and art critic
Montgomery Schuyler even defined the archway of the Empire State Building as
“one of the finest examples of architecture in town”. The development of foundation
and construction techniques led to the creation of functional buildings or bridges
that also shaped the city skyline. The combination of technical accuracy and aesthetics
allowed for increasingly safe, stable and beautiful constructions.
During the 20th century, the use of pneumatic foundations was still widespread in
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New York. This technique was used to lay the foundations for the Empire State
Building, but also for other structures, such as the Mutual Life Building (1900), the
Hudson Terminal (1906), the Federal Reserve Bank Building (1924) and the Verizon
Building (1926). However, the rocky soil was still a source of problems. When erecting
residential buildings, concrete tubes were often preferred, because they can penetrate
a wider range of materials and, more importantly, be installed deeper into the ground
(up to 30 meters). This procedure consists of sinking steel tubes into the ground,
emptying them completely and filling them up with concrete. In 1920, the same type
of foundations were prepared for the famous building of the Bank of Manhattan at
number 40, Wall Street. This was one of the tallest skyscrapers in the world, before
the construction of the Chrysler Building.
As far as bridge foundations are concerned, pneumatic foundations were temporarily
left aside to develop other, more innovative techniques, such as the artificially built
sand island method. Here, the caisson is installed by using a cofferdam full of sand
as a barrier and the open-dredging method. In 1935, the artificially built sand island
method was used to install 51.8-meter-long caissons to the same depth for the Huey
P. Long Bridge, spanning the Mississippi River in New Orleans. Foundations could
not be installed into the clay soil with traditional techniques. In The Huey P. Long
Bridge, a book dedicated to the history of the bridge, Tonja Koob Marking and
Jennifer Snape affirm: “when a downstream Mississippi River railroad bridge was
initially conceived in 1892, the soft, deltaic soils and difficult river environment made
its construction a near impossibility with existing methods. The final plan, developed
30 years later by bridge engineer Ralph Modjeski, pushed the limits of civil engineering
design and construction to make the bridge a reality. Bridge engineers still use some
of Modjeski's ideas almost 80 years later”.
In 2011, the American Society of Civil Engineers awarded the Huey P. Long Bridge
the National Historic Civil Engineering Landmark, which is granted to historically
significant structures in the United States and in the world, especially as far as civil
engineering is concerned. This designation has also been awarded to the Panama
Canal and to the Eiffel Tower.
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The artificially built sand island technique was used for another important American
bridge: the Bay Bridge of San Francisco. Completed in 1935, this 8-km-long
suspension bridge connects Oakland to San Francisco. As had happened with the
Huey P. Long Bridge, at first the project of the structure appeared an impossible
idea. The water was 30 meters deep in some areas; the bridge had to span a massive
area; traditional foundation techniques were not suitable for the San Francisco Bay
ground. The Bay Bridge is therefore an innovative structure from different points of
view. First of all, its foundations required the construction of the biggest caisson ever
built (28 x 60 meters). The construction of the center anchorage required 55 steel
tubes full of compressed air to be embedded into a caisson and installed into the
Bay ground. A special clam-shaped digging apparatus, called a “clamshell”, was
dropped through the steel tubes to dig into the Bay mud.
The first steel tube was installed into the ground to the desired depth, capped and
filled with compressed air. The other steel tubes were installed in the same way. With
this technique, the caisson could be sunk 67 meters below the water level. The Bay
Bridge therefore shattered the record for the deepest foundations in the world - at
least until the Forties. All the towers (a total of four) were built by sinking a group of
steel piles into the ground to create a watertight cofferdam, draining the water and
installing the foundations. Hammerhead cranes located upon the towers were used
to create the steel structure. Finally, the construction of the Bay Bridge shattered
another record as it required the building of a tunnel through the Yerba Buena Island,
to connect the East and the West Bay. This tunnel is listed in the Guinness book of
World Records as the largest tunnel in the world, measuring 26 meters in width and
17 meters in height.
The need for new connections facilitating trade encouraged the creation of new,
remarkable structures: for example, the Panama Canal, connecting the Atlantic Ocean
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to the Pacific Ocean and cutting across the Isthmus of Panama in Central America.
In 1907, engineer John F. Stevens and colonel George Washington Goethals supervised
the construction of this colossal structure, measuring almost 80 kilometers in length.
The digging was the most complex part of its construction: workers excavated 200
million cubic meters of soil and sand and built locks of over 20 meters in height. The
construction of the Panama Canal required a total of more than 30 years from design
to inauguration. Problems encountered during the digging encouraged the development
of studies on soil mechanics and soil composition.
One of the main differences between past and present foundations is our greater
knowledge of soil behavior and its different responses according to its geographical
area. A significant contribution to gaining more knowledge in this field was given by
a man who was born in Prague during the 19th century and worked at the M.I.T. and
at Harvard. Commonly considered the father of soil mechanics, Karl Terzaghi wrote
Soil mechanics in engineering practice, which is still essential reading for engineering
experts all around the world. But let us take a step back: first, what is soil mechanics?
By definition, it is a discipline of civil engineering which studies soil and rock behavior
in relation to engineering activities, on a scientific and mathematical basis. As you
may have noticed during this journey throughout the history of great structures, many
bridges, cathedrals and buildings collapsed or were irreparably damaged because
foundations were installed with no regard for the type of soil of the site. Otherwise,
they would still be standing today. Entire structures were compromised because no
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one took care to think about their “base”. It is essential, instead, to have a deep
knowledge of the soil, so that it is possible to anticipate its reactions and its behavior
and build more solid bases for more durable structures. Karl Terzaghi played a
significant role in stressing the importance of this kind of study. He investigated the
composition of soil for the first time and, in 1948, elaborated the principles of soil
mechanics. He also expressed the concept of effective stress - “a force acting on
soil particles” - as the interaction between solid particles and water in unsaturated
soil pores. Terzaghi was aware of the lack of resources of his time, but he was also
convinced that in-depth knowledge of soil behavior was key to development in civil
engineering, even without high tech means.
By investigating the mechanisms underlying soil behavior, especially in the long term,
Terzaghi developed methods to keep these mechanisms monitored and ensure the
stability and safety of foundations in every type of soil. In the preface to Soil mechanics
in engineering practice, he wrote: “in the overwhelming majority of jobs, no more
than an approximate forecast is needed. If such a forecast cannot be made by simple
means, it cannot be made at all. If it is not possible to make an approximate forecast,
the behavior of the soil must be observed during construction work, and the design
may consequently have to be modified in accordance with the findings. These facts
cannot be ignored without defying the purpose of soil mechanics”. Simple means,
knowledge and awareness: it is certainly better if high tech means are available, but
research and a scientific and accurate approach provide the base for a stable and
resistant structure.
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During the last 50 years, this new awareness has led to real, apparent development
in soil mechanics, in the building industry, in foundation engineering and in architecture.
Let us take, for example, skyscrapers. The race to build the tallest building required
larger, safer, more durable foundations. In 1931, the Empire State Building of New
York was completed. Everyone knows it as the highest skyscraper in the world until
the construction of the Twin Towers of the World Trade Center, in the Seventies.
In Skyscrapers and the men who build them, William Starrett argues that the building
of skyscrapers is a “strife against the elements”, since “foundations are planned
away down in the earth alongside the towering skyscrapers already built. Water,
quicksand, rock and slimy clays bar our path to bedrock”. Designed by Shreve, Lamb
& Harmon, the Empire State Building stands 381 meters high (without its antenna
spire). The architectural firm laid concrete foundations around 17 meters deep
underground. Hundreds of workers dug into the rocky soil to make sure that the
huge steel structure would be perfectly supported.
In New York, everyone seems to want to touch the sky: the World Trade Center was
built during this period. This complex of 7 buildings includes the Twin Towers, which
have sadly become famous for being destroyed in the September 11th attacks of
2001. Each stood over 410 meters high. Minoru Yamasaki & Associates and Emery
Roth & Sons designed their extraordinary foundations, laid over 21 meters deep into
the rocky soil. Over 914 cubic meters of gravel and rocks were removed to make
way for these foundations, measuring 298.7 meters in length and 155.4 meters in
width. Bentonite slurry trench cutoff walls were used to create underground walls
preventing damage to the foundations of the surrounding buildings and streets. In
the United States, the foundations of the “WTC” are called “the bathtub” because
of their huge dimensions protecting Lower Manhattan from possible flooding from
the Hudson River. Even though they were quite fragile, the foundations did not break
following the collapse of the towers. However, they did cause problems during the
reconstruction of Ground Zero. Trevi Icos, the subsidiary U.S. Company of the Trevi
Group, contributed to the consolidation of this area, which is meaningful both for the
American community and for the entire world.
Today, many of the great structures which strike the eye of even the most inexperienced
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observer are mostly located in the Eastern part of the world. In the United Arab
Emirates, Dubai's Burj Khalifa skyscraper, opened to the public in 2010, is currently
the highest building in the world (828 meters high with the antenna spire); not to
mention the Mecca Royal Hotel Clock Tower in Mecca, Saudi Arabia, standing 601
meters high with the antenna spire. They both required on-site investigations and
soil sampling before the foundations and the supporting structure could be built. The
Taipei 101 building (508 meters high) of Taiwan, the third tallest building in the world,
required the same kind of procedure. In this case, engineers carried out loading tests
and test installation of pieces before installing the 30-meter-deep pile foundation.
However, the most remarkable development in foundation engineering is the one
that cannot be seen with the naked eye: the one that hides below the ground. The
commitment, dedication and attention of all the people working today to build more
solid and sophisticated foundations are the engine to this development. As we have
already mentioned, in 2012 the Trevi Group shattered the record for the deepest
foundations ever laid. Reaching a depth of 250 meters underground, the Tiger
hydromill, designed by Soilmec, reached limits never thought possible before. Clearly,
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challenges in soil mechanics can be met and overcome, especially as far as hydraulic
infrastructures are concerned. We are reaching new, incredible limits, not only those
stretching out to the sky, but also those we have below our feet, supporting our
houses, our offices and our great structures.
What does the future hold for foundation engineering? The history we have seen
together teaches us to always remember knowledge and techniques from the past,
but also never to “lie down”. Curiosity about evolution and progress is key to achieving
important goals that can only be accomplished with teamwork, research and the
development of new technologies. As you will have learned by now: something great
and durable can only be created on the most solid of bases.
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Skyscrapers
Since the medieval age the men desire to build the tallest tower but the height of these
buildings was limited by how massive and heavy they had to be at the base. During the
XIX century the ability to mass produce steel, the invention of safe and efficient elevators
and the development of improved techniques for measuring and analyzing structural
loads and stresses allows to build structures up to the sky: the Skyscrapers.
Designing a skyscraper involves creating a structure that not
only support vertical load, the engineers must ensure that
the building will not be toppled by a strong wind, and also
that it will not sway enough to cause the occupants physical
or emotional discomfort. The construction process can be
divided in three stages: Substructure, superstructure and
exterior construction. The foundations, either piles or caissons,
penetrate through upper layers of soft soil and stretches
down all the way to bedrock. Metal pilings connect the
substructure floor with the bedrock layer of underground to anchor the building above.
Once the steel is in place, the entire structure is covered with concrete. The superstructure
of a skyscraper is its steel skeleton. Vertical metal columns are linked with horizontal
beams to create solid and flexible frameworks for each floor. Biggest buildings also have
diagonal beams running between the girders to give extra strength to the skeleton. The
exterior walls themselves merely enclose the structure. They are constructed by attaching
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panels of such materials as glass, metal, and stone to the building's framework.
At the beginning of the twentieth century starts the race for the world's tallest building
in all the United States, the corporations built skyscrapers for the promotional value to
increase name recognition. A real estate boom occurred in the US after the end of the
First World War, with a particular surge in the construction of new skyscrapers in New
York and Chicago. In a couple of years between 1930 and 1931 was a real “playoff game”
with field goals and surprise ending. The gravity became obsolete. As a proud reaction
to the Wall Street crash of 1929 the Bank of Manhattan Company completed in outstanding
production time the construction of
the tallest skyscraper of New York.
Under the supervision of architect H.
Craig Severance the construction
of the Trump building (also known
by its address: 40° Wall Street) began
in May 1929 and the Bank's opening
day was the 26 May 1930, only 12
m o n t h s a f t e r. T h e b u i l d i n g
architecturally can be considered a
modern interpretation of French
Gothic. From the center of its giant
base rockets the tower that culminates in a green-colored metal cap to a height of 283
m divided in 71 floors. Unfortunately for Severance in the same period was commissioned
to his ex-partner William Van Alen the design of the Chrysler building. Walter Percy
Chrysler (1875-1940) was born in Wamego, Kansas, and early in life became a machinist
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and toolmaker. After a rapid climbing on Buick and General motor companies he took
charge of the Maxwell-Chambers motor company and after five years reorganized it under
the name of Chrysler Corporation in 1925. For Walter P. Chrysler building the tallest
building in the world was a status symbol. The foundation work began on 11 November
1928, the weight of rocks and soils removed from the site was 75000 tons and after
excavation the concrete was poured to a depth of 21 m below Lexington avenue. The
steel superstructure erection started on March and the last structural beam was placed
on September with an incredible production of four floors completed per week. The
exterior is an art deco tour-de-force, its abundance of Nirosta steel makes for one of the
most compelling skyscraper surface anywhere. The 40° Wall Street building rose seventy
stories, 282 m tall and the Chrysler was slate at 77 stories, 262 m. For an instant it
appeared that Severance won but the unthinkable happened. Secretly the 55 m long steel
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spire was transported and assembled inside the Chrysler tower. Just few month after the
40° Wall Street building opening day the Chrysler's spire was lifted at the building's top
and in about ninety minute the yearlong contest was decided: the Chrysler Building with
its 319 m was officially declared the “World's Tallest Building”. The Chrysler is a monument
to an age; it is the silver trinket on Manhattan's bracelet but It would not keep this title
for long: one year later the Empire State Building was erected.
The Empire State building project was commissioned to the renowned New York architecture
firm of Shreve, Lamb & Harmon. The site chosen for the skyscraper was occupied by
the original Waldorf-Astoria hotel.Demolition of the hotel commenced on October 1929
and the Empire State building foundation work started on 17 March 1930. Enormous
blocks of concrete were placed 17 m below the sidewalk and served as bases beneath
the largest steel columns ever fabricated, each weighing over twelve tons to the foot. The
skyscraper is an Art Deco colossus, its curtain wall was composed of Indiana limestone,
stainless steel, aluminium, granite and glass. The Empire State building was opened to
the public with great fanfare on 1 May 1931. For the first time the number of floors in a
skyscraper would contain three digits and with 102 floors and 443 m height the Empire
State building became the world's tallest skyscraper for nearly 40 years until the construction
of the World Trade Center's North Tower in late 1970.
Rif. Bibliografici:
The American Skyscraper, 1850-1940:
A Celebration of Height by Joseph J. Korom
www.madehow.com/Volume6/Skyscraper
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MT-22 “ Pali Trevisani”
One of the first crawler type pile-driving machines
ParteDUE_UK 22-01-2015 15:47 Pagina 1
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3.
Chap.
The Trevi Group and Soilmec S.p.A.:
a Success Built on Solid Foundations
The Trevi Group is a world-wide leader in the foundation equipment and geotechnical
engineering industry both for its services and for specialized sector machinery and
equipment supplied by its mechanical division Soilmec S.p.A.. The company is one
of the leaders in the petroleum industry well drilling sector.
A great story is better savored from the beginning: the journey towards success is
made of many, individual steps. Davide Trevisani took the first step when he
established the Trevi Group with the name “Impresa Palificazioni Trevisani Geom.
Davide” in Cesena, in 1957. No one could have imagined that a combination of
determination, dedication to excellence and commitment to success would lead the
company to the achievement of internationally admired success. All
those steps would write essential chapters in the history of the
Group. Let us have a look at some of the milestones in the
history of the Trevi Group so far.
The great turning point for the international growth of
the company begins with the building of the foundations
of Apapa Road, in Nigeria. It is a central artery close
to the city of Lagos and it connects the port city to the
rest of the country: thousands of people use it every day.
This was the first large-scale international project of great
responsibility. It is further proof that commitment to what we
believe in and passionate collaboration lead to extraordinary
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accomplishments. Further development of innovative technologies is a
natural response to this success. Davide and his brother Gianluigi therefore
decide to establish Soilmec S.p.A., providing cutting-edge equipment
for the ground engineering industry.
During the Seventies, the Trevi Group was able to deal with many different
challenges. In 1971, the company obtained a contract for the constraction
of the foundation piles for the bridges on the 5,000-kilometer-long
Paraná River, running through Brazil, Paraguay and Argentina. It is a
mostly navigable river, mainly used for fishing-related activities. Pilotes
Trevi sacims was founded during this period: it has provided special
foundations and other infrastructure for over 40 years. The Group prepared
the foundations for the Zárate-Brazo Largo road and railway suspension
bridges, connecting the cities of Zárate and Brazo Largo. The structure
is today an important - and colossal - road link between the southern
part of Entre Ríos and the north of Buenos Aires. Furthermore, they were
the first large span cable-stayed bridges in the world, a particular type
of suspension bridge where cables anchored to piles support the bridge
deck. The Trevi Group shattered an important record with the installation
of piles of 2.2 meters in diameter to a depth of 74 meters below the water
surface. Needless to say, the company kept obtaining contracts in
Argentina - providing over 300 interventions to the present day. One
example is the contract for the construction of foundations for the RosarioVictoria Bridge (2003) connecting the city of Rosario (province of Santa
Fe) and Victoria (province of Entre Ríos), which required the underwater
installation of 630 piles measuring over 50 meters in length; or the
construction of several dams, such as the Los Caracoles dam in the
province of San Juan (2007).
In 1976, the Trevi Group obtained the contract for the construction of
new platforms for the port of Bandar-Abbas, the most important port
city in Iran on the Straits of Hormuz, at the entrance to the Persian Gulf.
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Although the Khomeinist revolution interrupted the execution of works, the Iranian
Port Authority appointed the Group to expand the port in 2001, showing how the
company was able to build good customer loyalty. Today, the new commercial port
of Bandar Abbas, called “Shahid Rajaee Special Economic Zone”, covers an area
of 20 km2 and provides advanced structures allowing huge quantities of goods to
be stocked and ships to be loaded and unloaded quickly.
During 1979, the Trevi Group developed several innovative technologies. The company
designed and patented cutting-edge Vibrotrevi, allowing piles to be cast driven in
situ without soil removal. This driven pile reaches maximum depths of 25 - 27 meters,
with diameters ranging from 335 to 610 millimeters. Furthermore, the Trevi Group
designed the Trelicon technology, a pile that avoids decompressing the soil and
using bentonite mud for drilling. Its most appealing qualities? It is perfect for drilling
in urban areas, as it eliminates vibration and reduces noise emissions; it greatly
simplifies the disposal of debris and allows for a much wider range of diameters and
lengths.
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A new important contract led to a successful collaboration with Ing. Giovanni Rodio
& C., one of its competitors at the time: the construction of the Khao Laem Dam,
in Thailand. The dam was built on the Quae Noi River, a few hundred kilometers from
Bangkok and close to the Burmese border. Thailand wanted to reduce its dependence
on oil imports by fostering better exploitation of its water resources. The dam, with
a concrete lining measuring 90 meters in height and 1,000 meters in length, supplies
electric power and water for irrigation to a wide area of the country. The Trevi Group
carried out drilling and grouting work for the construction of appropriate abutment
tunnels, while Trevi-Rodio prepared the diaphragm wall (a special type of concrete
wall) and carried out drilling and grouting work for the construction of the dam. This
collaboration led to the acquisition of Ing. Giovanni Rodio & C. by the Trevi Group,
further improving its competence. The Società “Ing. Giovanni Rodio & C. Impresa
Costruzioni” was a leading company in the civil engineering sector at its very
beginning. Founded in 1921, it was the first company to put civil engineering theories
into practice, due in part to the friendship between engineer Karl Terzaghi and
Giovanni Rodio. The Trevi Group and Rodio achieved perfect synergy as they shared
an international vision and dedication to the development of innovative technologies.
Ing. Giovanni Rodio & C. had patented the “lubricated pile”, a particular type of pile
which endures soil settlements and conceived the first thixotropic and chemical
blends improving the characteristics of the soil. He also held the Rodio-Dehottay
patent concerning the use of carbon dioxide to freeze the soil - used in 1937 for
work at the Ara Pacis Augustae of Rome, installed large-scale piles and designed
small-scale piles called Tubfix Micropiles. Today, the Trevi Group uses Rodio's past
experience in this sector with renewed energy.
These are only the first steps towards further extraordinary accomplishments. Before
1990, the Group had already patented the Reinforced Protective Umbrella Trevi
Method, a special technology for drilling tunnels in loose ground with equipment
designed by Soilmec S.p.A.. During that year, technologically advanced Japan
imported the Trevi Method and equipment for the realization of the Hasaki Tunnel
& Bridge, a complex project for the construction of bridges and tunnels on the
Hokuriku Expressway, close to the port city of Niigata.
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Two years later, Trevi Construction Co. Ltd. of Hong Kong, part of the Trevi Group,
was awarded two contracts for the construction of the Ertan Dam on the Yalong
River, in the People's Republic of China. It was a unique opportunity to compete in
markets in the East. First, the company prepared an impervious diaphragm wall for
upstream and downstream cofferdams; secondly, it carried out the consolidation,
waterproofing and drainage of the foundation rock of the dam. The electric power
plant houses six generators supplying power equal to 3300 MW: it is the largest and
most powerful power plant in China. The Group availed itself of an international team:
engineers coming from all continents worked to complete this massive structure,
measuring 240 meters in height and 774,7 meters in length. It is one of the ten tallest
dams in the world. This intervention was a milestone in the history of the Trevi Group,
as it shattered several records. During the same period, more precisely in 1994, the
Trevi Group participated in a culturally significant - and purely Italian - project: the
consolidation of the Tower of Pisa, a building of great historical value and one of
the most outstanding symbols of Italy in the world. We will talk about this later: the
fine connection between technological innovation and art deserves further in-depth
consideration.
However, the restoration of the Tower of Pisa was not the only remarkable restoration
the Trevi Group contributed to. Its participation in the construction of the new Library
of Alexandria in Egypt, in 1996, showed how seriously the company considers the
safeguarding of the cultural and artistic heritage. Everyone knows the history of this
library: founded during the 3rd century B.C. under the reign of Ptolemy II Philadelphus,
it housed a breathtaking amount of erudite books. This precious treasure was entirely
destroyed by a fire, probably before the 7th century A.D. In 1990, the Egyptian
government in cooperation with UNESCO announced plans to revive the Library by
restating its cultural legacy to the entire world. With cutting-edge architecture, the
Bibliotheca Alexandrina rises again like a phoenix from the ashes. In the heart of
Alexandria, a large city overlooking the Mediterranean Sea, the new library acquired
around four million books and precious collections of Egyptian manuscripts. The
monolith and rough granite main building holds inscriptions in ancient and modern
letters in all the languages of the world; the entire steel frame structure has aluminium
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screens with double-glazed glass panels protecting the inside from the sunlight. The
overall structure of the Bibliotheca Alexandrina covers 85,000 m2 and contains huge
shelves for storing millions of books, a manuscript restoration laboratory - this was
one of the main functions of the ancient library - a large reading room (with 2,000
seats), a children's library, a science museum and a school of information science.
Contributing to the creation of this great, modern structure, the Trevi Group became
part of a remarkable cultural event renovating and celebrating an ancient institution
with a fresh, new vibe. The international perspective of the new Library of Alexandria
could make King Ptolemy II's dream of “collecting all the books of the world in this
library” come true in our time.
In 2003, the Trevi Group contributed to another remarkable intervention in collaboration
with UNESCO: the restoration of the Bamiyan Buddhas in Afghanistan. The
destruction of these two enormous statues by the Taliban regime put the stability of
the site in jeopardy. The Group restored the remains and prepared the area for future
reconstruction. We will talk about this later: the dedication of the Group to ensuring
the stability of the site deserves to be fully described.
During the last decade, the Trevi Group has performed a number of important
interventions, especially in the United States. The company contributed to the
construction of the Central Artery of Boston, also called “the Big Dig”, a real
“megaproject” to reroute the Interstate 93 (the chief highway through the city of
Boston) into a long underground tunnel (almost 6 kilometers). It was one of the most
complex infrastructure projects ever undertaken in the United States and it involved
two main projects. First, the existing six-lane highway was replaced with an underground
highway and two bridges spanning the Charles River in the northern part of the path;
secondly, the construction of a tunnel extended the Interstate 90 to Logan International
Airport.
In 2003, the Trevi Group contributed to the consolidation of the Walter F. George
and the Tuttle Creek dams. The first one is located in the 136-km-long Walter F.
George lake, at the boundary between the states of Georgia and Alabama. The project
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concerned the construction of a diaphragm wall located upstream of the dam on the
Chattahoochee River. The job was so successful - piezometric examinations showed
significant reduction in water infiltration - that the Group was awarded contracts for
the construction of three other dams. Walter F. George's diaphragm wall was plastic,
while the dam of the Tuttle Creek Lake, in Kansas, required the construction of 350
13.7-meter-long and 21-meter-deep cement bentonite walls perpendicular to the
axis of the dam. The contract also included the construction of a working platform,
the restoration of the downstream embankment and the overlay of the upstream face
of the dam.
In 2010, the Trevi Group performed interventions in two of the most important
universities in the United States, Harvard University and the Massachusetts Institute
of Technology (MIT). In the first case, the Group built a diaphragm wall for the
Harvard Art Museum (Massachusetts), designed by the famous architect Renzo
Piano. The museum was extended into a huge building housing three existing
museums: the Fogg Art Museum, Harvard's oldest art museum, with collections from
the Italian early Renaissance and the Pre-Raphaelites; the Busch-Reisinger Museum,
the only museum in North America dedicated to the study of art in German-speaking
countries in all media and in all periods; and, lastly, the Arthur M. Sackler Museum,
dedicated to Asian art, with collections spanning from Chinese bronzes to Buddhist
cave-temple sculptures. It was a challenging task protecting the historical and artistic
importance of the area while dealing with technical problems due to the complex
characteristics of the soil and the limited time available - work had to be completed
before the end of 2010. The successful completion of work is a further demonstration
of the technological skills and know-how of the Trevi Group. The company is in fact
also always particularly attentive to the protection of art. In Boston, the Trevi Group
was also appointed to construct diaphragm walls for the MIT, one of the most famous
research universities in the world.
In conclusion, we would link to stress the importance of an intervention which attracted
media attention from all over world. The Trevi Group constructed the diaphragm wall
for the foundations of the new transportation hub of the World Trade Center, with
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around 1-km-long pedestrian tunnels. As you can imagine, this project was loaded
with expectations, the need for excellence, and emotional factors linked to the
ideological importance of this site after the destruction of the Twin Towers in 2001.
Completed in 2007, works proved to be tricky not only on the emotional side, but
also on the practical side: the rocky underground soil of the site is composed of
inclined layers that are difficult to treat. And yet, once again, the Trevi Group met
and overcame the challenge. Customized machines designed by Soilmec S.p.A.
were imported to the Big Apple and precision and commitment made the project a
success. We can now say that the foundations of the new World Trade Center, and
the hope for the rebirth of the site, are stronger than ever.
Today, the Trevi Group, world-wide reputed leader in the ground engineering industry,
keeps growing, developing innovative technologies beyond imagination and operating
successfully in every part of the world. With 43 different nationalities, the number
of members of this large, international team keeps growing every year and, in 2012,
it reached 6,689 employees. What distinguishes the Trevi Group is its international
perspective: the drilling services divisions are located in the United States, Canada,
Panama, Colombia, Venezuela, Peru, Chile, Brazil, Argentina, Germany, Sweden,
Denmark, Austria, Italy, Turkey, Algeria, Nigeria, Angola, Mozambique, Iran,
Oman, the United Arab Emirates, Qatar, Kuwait, Saudi Arabia, Hong Kong, the
Philippines, Australia and New Zealand. Furthermore, the mechanical engineering
divisions are located in the United States, Colombia, Brazil, France, the United
Kingdom, Italy, Germany, Egypt, Iraq, Saudi Arabia, the United Arab Emirates, Russia,
Belarus, China, Hong Kong, Japan, India, Singapore and Australia.
This international perspective translates into dedication to the development of
innovative technologies in the ground engineering industry, ensuring maximum safety,
efficiency and respect. The Trevi Group has also participated in numerous international
charity projects named “Social Value”. This megaproject involved, for example, the
donation of a complete system for groundwater exploration and exploitation to create
drinking water wells in Sudan and Uganda for the “Water for life” project, support
to the Children's Home of Vayalur, India, for the “Mariella Children's Home” project,
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the construction and start-up of the new Nutrition Center and of a “water point” in
Cité Soileil, Haiti, and a graphic art competition on sustainability addressed to pupils
and students of the primary, secondary and high schools of Cesena for the project
“Colouring energy”. Ethics is one of the pillars of the Trevi Group: a trustworthy,
eclectic, but also “good” company.
The Trevi Group has taken part in projects not only where emotions, but also our
own past and its protection, are concerned. The company takes seriously the
safeguarding of historical heritage and shows it concretely. In the next chapter, you
will read about two special cases where Trevi Group used its competence to achieve
this essential and complex aim.
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4.
Chap.
History, Art and Engineering:
the Trevi Group's Main Restoration
Projects
Why is the past so important? Can the safeguarding of the past, our predecessors'
testimonies and the knowledge underlying our most important historical and artistic
heritage actually be useful to us?
These questions are pivotal to really understanding how much commitment and
dedication are required in the safeguarding and restoration of historical heritage.
Throughout our journey from the very first types of foundations to today's more
modern and sophisticated ones, we have seen how every step taken by men and
women in human history has contributed to laying one more brick in the gigantic,
never-ending edifice our past represents. What would this building be without
foundations? What if no one kept them monitored to prevent them from being
damaged or worn out?
Here lies the importance of our past. Discoveries from the earliest ages may gain
new interest as fast as they had been forgotten. As we mentioned, some foundation
engineering techniques that were used centuries ago are still used today: they have
been updated, improved and developed. Humankind has always been able to create
great things that are still - and must be - standing in front of us.
The Trevi Group is engaged in preventing important evidence of our past from being
lost. The Group has performed several interventions for this purpose, among which
two deserve particular attention. Firstly, the restoration of the foundations of the
Leaning Tower of Pisa, from 1990 to 2002, in Italy. Secondly, the stabilization and
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recovery project on the archaeological site of two Buddha statues in the Bamiyan
Valley, Afghanistan, in 2001. This possibly lesser-known structure perfectly represents
the importance and urgency of international safeguarding of historical and artistic
heritage. Located far from each other and with different cultural backgrounds, the
West and the East share the same mission: protecting their historical and artistic
heritage beyond present political or economic issues.
We are responsible for our identity, but our predecessors have also contributed to
defining it. UNESCO (United Nations Educational, Scientific and Cultural Organization)
created the World Heritage List including Piazza dei Miracoli and the Tower of Pisa
and supported the restoration of the Buddhas of Bamiyan.
The World Heritage Convention of 1972 describes a World Heritage site as “the link
between past, present and future generations”. These words perfectly summarize
the importance of the safeguarding of the historical and artistic heritage that has
been left to us. The Trevi Group is committed to keeping this link strong and intact.
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4.1
The Restoration of the Leaning Tower of Pisa
The cathedral of Santa Maria Assunta, the Baptistry of Saint John, the Campo Santo
and the famous campanile, more commonly known as “The Leaning Tower of Pisa”,
may seem to defy the laws of gravity to a tourist who does not know much about
architecture and engineering. Italian poet Gabriele d'Annunzio was so impressed by
the breathtaking beauty of these monuments that, in the novel Forse che sì forse
che no, published in 1910, he wrote: “the Ardea hovered in the sky of Christ, over
the meadow of Miracles”. From that moment on, everyone started calling the cathedral
square of Pisa “Piazza dei Miracoli” (“square of Miracles”): its extraordinary monuments
are as unique as miracles.
The most remarkable miracle is in fact the Leaning Tower of Pisa, which has been
proposed as one of the Seven Wonders of the World. As an internationally renowned
building, hundreds of thousand of tourists visit it every year, take pictures in front of
it and send home postcards of it. Unique and special as only great monuments (or
miracles) can be, the Leaning Tower of Pisa has become a symbol. And yet, there
was a time when this historically and artistically valuable structure was put in jeopardy:
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the Trevi Group's technologies and machines became essential
to bringing the monument back to its original splendor and
safety.
The Leaning Tower of Pisa is the campanile of the cathedral
of Santa Maria Assunta overlooking the famous Piazza dei
Miracoli. Its construction began in 1173. Though the identity
of its creator is still uncertain, the name of Bonanno Pisano
was found on an urn in the tower during an archaeological
dig: the creation of the monument is thus usually attributed
to the Italian sculptor. Work was interrupted a few years
later, while the third floor was being completed. The reasons
behind the interruption are not clear: some people argue
that the main cause was foundation failure, while others
claim that political or economical issues brought the
construction to a stop. However, it seems that, just a short
time after the beginning of the construction, the first three
floors already showed an inclination. In 1275, engineer
Giovanni di Simone took charge of the project and mostly
completed work by adding three more floors. Apparently,
it was an attempt to “correct” the inclination of the tower,
as can be assumed by studying the inclination starting
from the third floor. Work was not fully completed until the
middle of the 14th century, when Giovanni Pisano built the
bell-chamber.
The Tower stands around 60 meters high. It is composed
of a cylindrical masonry body surrounded by loggias with
arches and columns. The structure is subdivided into eight
segments called “orders”, including the
ground floor, six galleries and the
bell-chamber. This open bell-
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chamber is linked to the ground floor and to the Sala
del Pesce (“Fish Room”, named after a bas-relief
depicting a fish) by three staircases, the last of
which is a spiral staircase of 293 steps leading to
the top of the Tower.
The ground below the Tower consists of a wide
range of soil layers. The underground soil is
generally composed of silts, clays and fine sands.
The different layers can be divided into three different
“complexes”: the first one is called Complex A and
is composed of silts, clays and sands extending to
a depth of about 10 meters underground. Below the
southern part of the Tower, the sand layer tends to
get thinner and more compressible: this could be the
main cause of the initial inclination of the Tower.
Reaching a depth of about 40 meters underground,
Complex B is mainly composed of clays, while Complex
C consists of lower sands reaching to a depth of around
70 meters.
There are two possible causes of the inclination of the
Tower of Pisa. Firstly, the fine sands of the underground
soil are usually more compressible. Secondly, the weight
of the Tower caused a deformation in the ground right
below itself, and the layers of soil separating upper
sands from clays is minimal. Therefore, the inclination
of the Tower was not due to a failure of the foundation
soils, but to the characteristics of the site where the
Tower was built.
As we have seen, the inclination of the Tower
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of Pisa became apparent just a short time after its construction and a long before
its completion. This is why several commissions have been formed throughout the
centuries in order to find a solution to the problem, while preserving the integrity of
the monument. It certainly was a difficult task, so difficult that several commissions
were formed until the most recent times without finding any good solution. The very
first commission was formed in 1292 by two magistri lapidum and a magister lignaminis
- experts in masonry and wooden buildings - and it proved to be particularly helpful
as it prepared a formal minute describing precise measurements which would be
useful in the future. In 1840, a second commission was appointed to drain a “catino”
(“basin”) that had just been excavated in an attempt to “counterbalance” the weight
of the Tower. However, the work did not meet with success. In 1902, the collapse
of the tower bell of the St Mark's Cathedral in Venice was the straw that broke the
camel's back: commissions have followed one another ever since, in a desperate
search for a solution.
In 1965, the first commission counting among its members a group of geotechnical
engineers was formed, headed by physicist Giovanni Polvani. This commission
managed to gather the majority of the data about the Tower of Pisa we have today.
However, even though an international tender was called, no contractor was really
acknowledged to be capable of performing the stabilization work of the Tower without
putting its historical and artistic value in jeopardy. But time was running out: in 1989,
the Torre Civica of Pavia collapsed bringing a number of victims, increasing the
pressure for safer monuments. In 1990, the International Committee was able to put
theory into practice. The heterogeneity of its members was its main quality: it was
an international team, with skilled restorers, geotechnical engineers, and art historians.
The Committee was assisted by the Consorzio Progetto Torre di Pisa, which was
appointed to carry out studies and monitor the site. Science and history thus met
for the first time: the synergy between these apparently different fields was key to
the extraordinary restoration of the Tower.
The race against time had begun. But things could not be done too fast: a combination
of efficiency and effectiveness was required. The Committee soon identified two
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main issues to be dealt with: firstly, the stress in certain areas of the Tower, which
could have led to sudden collapse of the entire elevated structure; secondly, the risk
of the Tower collapsing in the event of failure of the foundation soils.
The Committee immediately ensured the safety of the area with temporary measures,
implementing permanent stabilization actions. To achieve this, in 1992, the first
“cornice” was hooped with steel strands. Once the most stressed areas of the
structure were identified, they injected cement grouts and inserted a number of
stainless steel reinforcement bars to consolidate the masonry.
In-depth investigations on the underground soil and on the inclination of the structure
showed that a slight reduction of the inclination would be sufficient to halt its progress.
The Committee decided to reduce the inclination of the Tower of Pisa by one-half
of one degree by inducing a controlled settlement at the north side of the foundation.
This project would improve the safety of the structure, but it was also respectful of
its integrity and its historical value. After examining several possible ways of achieving
this result, the Committee opted for the method of underexcavation, consisting of
controlled extractions of small volumes of soil below the foundation level.
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The task was so complex that it required further precautions before work directly
on the Tower was begun. In a secluded corner of Piazza dei Miracoli, a large-scale
experimental foundation was built in order to study the consequences of the procedure
on the soil. Despite the positive results obtained at this stage, the Committee could
not be certain of how the actual procedure would have affected the structure. For
everyone working on the site, dedication and care were the keywords: the most
important thing was to protect the Tower and avoid damage that could irreparably
affect its cultural value. For this reason, a provisional safeguard system was installed,
consisting of two backstays - structures made of stainless steel cables preventing
the inclination of certain areas of a building - connected to the Tower at the thirdstorey level and to two metal frames located north of the Tower. During the spring
of 1999, the safeguard system allowed for safe preliminary (and limited)
underexcavation. Results were positive: the stabilization of the Tower of Pisa was
successful and, since September of that same year, movements of the Tower have
ceased. The following phase was the final excavation, which lasted one year, from
2000 to 2001. Final underexcavation work is best summarized by these numbers:
38 cubic meters of soil were removed, 30% of which from below the foundation
and 70% from north of it, with maximum penetration below the foundations at
a depth of 2 meters. This procedure produced such extraordinary results that
temporary structures, such as the circumferential hoops and the safeguard backstays,
could be removed even before the completion of the work. The anchor frames of
the safeguard system were the only structure that was not removed: they are still
discretely located behind the Opera Primaziale, as a testimony of the great commitment
and dedication demonstrated during those 10 years of work to protect not simply
a building, but a true symbol.
The final work involved the consolidation of the Catino. The Committee decided to
connect it directly to the Tower, making it a sort of extension of the foundations of
the Tower. A circumferential element of the foundations was built and the continuity
of the floor of the Catino was restored. The oscillations of the ground water level
underlying the Tower, which is believed to be one of the main causes of its inclination,
were interrupted through a customized gravity drainage system. This system did not
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depend on its own pumping plant and allowed water entering the wells to be collected,
drained, pumped to the underground tank that collects rainwater from the Catino
and, finally, sent to the urban sewers. The system allows soil settlements to be
monitored and reduced, preventing inclination of the Tower caused by deformation
of the soil.
In 1995, the inclination of the Leaning Tower of Pisa (the angle of slant is now 3.97
degrees) was brought back to the level it was before the construction of the Catino,
which had seriously compromised its stability. It has never increased since. The
monitoring system installed during the operations was simplified to allow the monitoring
of the structure over time. This - still complex - system allows for monitoring of Tower
inclination, foundation movements, possible variations in crack width, variations in
structure body dimensions and seismic movements, all at the same time.
The Trevi Group met this challenge using its organizational and engineering skills in
order to protect the ideal of safeguarding historical and artistic heritage of objective
and emotional importance. For 10 years, the eyes of the entire world have been
focused on these works, where technology, science, expertise and heartfelt desire
acted in perfect synergy. The story we have told you was not merely the description
of an engineering intervention: it was the story of a rescue. The rescue of a monument
and something of limitless value: the value of history. Sometimes, only science and
expertise can protect beauty.
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4.2
The Buddhas of Bamiyan
This story begins in the Middle East, more precisely in Bamiyan, Afghanistan. The
climate in Bamiyan is unpredictable: the Valley is vast and dry, and surrounded by
mountains, but temperatures tend to fall several degrees below zero in winter. Bamiyan
is crossed by the Silk Road, a network of routes connecting Central Asia and China,
where trade between those worlds used to take place. Merchants and traders used
to travel through Bamiyan, but it was also a place where religious men traveled these were Buddhists, who eventually decided to move there and create cloisters
and places of worship. They were mainly hermit monks, living in an extremely
minimalist environment, sleeping in caves carved into the rock. Religious images
were essential for traditional daily worship rituals so they used to paint, carve and
dig into rock faces to shape them into religious images.
This is probably how the two magnificent tall Buddha statues were built. Sweat,
commitment and a strong faith brought about the construction of the Buddhas over
the course of two centuries, probably between the 3rd and the 5th century A.D.. The
region was wealthy, especially as far as culture was concerned: at the time, the
Kushans were in power and they deeply appreciated the value of culture. They built
schools, a cloister, and then, those gigantic statues, the first one standing over 38
meters high (Small Buddha). The second one (Great Buddha), standing 53 meters
high, was the tallest Buddha statue in the ancient world. They carved the statues
into the mountain, using mud and flake to add the details. It is also believed that the
Buddhas were covered in marvelous jewelry when they were first built.
However, the extraordinary construction of these statues is overshadowed by their
staggering destruction. During the 12th century, this culturally rich region fell under
the control of Islamic people, who did not appreciate religious images from other
religions. And yet, for several centuries, these great statues were left untouched:
after all, they did not depict gods but human beings, and they were constructed
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during a preceding period. Sultans and kings followed one another, but no serious
damage was caused to the Buddhas. They really did appear to be indestructible.
The veneration of icons and the icons themselves still constituted an unacceptable
insult to the Taliban, even though they dated back to 15 centuries earlier and there
were very few Buddhists left in that region. The decree issued by Mullah Mohammed
Omar did not prove very useful, though it stressed the importance of the safeguarding
of the two statues to facilitate tourism. The situation was degenerating and, apparently,
nothing could stop it: once music, sport and television had been prohibited, it was
a short step to the issue of the dreaded decree announcing the destruction of the
statues. On March 2001, the Mullah had changed his mind and, according to the
Times, he officially supported “execution”. No one would listen to the reprimands
of the international community or to the proposal to arrange for the transfer and
eradication of the statues. The threat of
the destruction of the Buddhas, which
had existed for 1500 years, led to an
international and domestic debate. While
the entire world looked in anxiety at the
future of the statues, a breach appeared
between the extremist and the moderate
sides of the Taliban regime. Perhaps, the
spark had been ignited by a singular event - rumor has it that a foreign delegation
had offered money to restore the statues and that this had made the Mullah angry,
as thousands of people were dying from hunger without receiving any humanitarian
aid. Or maybe it was just an attempt to assert the regime, to demonstrate something
to the whole world.
That spring, after heated debate, massive explosions destroyed the Buddhas. They
did prove to be very resistant in one way: the tall, strong hard-rock statues required
over a month to be almost completely destroyed with guns and dynamite. Some
details and parts are still visible today, such as the two huge niches in the rock where
the statues had been built.
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In 2002, international organizations started thinking about restoring the monuments
and taking safety measures in the area. Explosions had made the site unstable and
a sudden, even partial, collapse was believed to be imminent. In 2003, the area was
awarded an important international acknowledgment: inclusion on the List of World
Heritage in Danger. The reasons for inclusion are countless and apparent. Firstly,
the statues and the niches constituted a unique testimony to Buddhist art. Secondly,
their remains bear witness to how trading between Eastern populations traveling
along the Silk Road led to a multicultural evolution expressed through this form of
art.
It was high time to go from theory to practice. Archaeologists visited the site and
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examined the remains, trying to identify what could and had to be rescued; UNESCO
and the Japanese government - which provided funds - officially launched restoration
work. First of all, the Trevi Group carried out geological investigations on the soil of
the site, taking samples and performing laboratory tests and on-site inspections. Not
only were these works extensive and complex, they could also be dangerous: workers
could accidentally step on a landmine. Nevertheless, investigations carried on from
2002 until the completion of the restoration work. These showed that extreme
variations in temperature (hot and dry summers, cold and snowy winters) had to be
taken into account; that the rocks outcropping the area were mainly conglomerates,
especially siltstone - a particular type of sedimentary rock; and that water infiltration,
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gully erosion, and accumulation of mud are the main geomorphological processes
present in the area.
The results of the investigations led to the development of a feasibility study for the
consolidation of the Buddha niches and cliff. To achieve this, the installation of a high
precision crack monitoring system was required. This was essential for the preparation
of a temporary support infrastructure to keep the blocks stable, including during the
execution of work; to minimize the impact of drilling; and to proceed with the
stabilization of the back walls of the niches. Engineers, archaeologists and specialists
in the conservation of cultural property cooperated in perfect synergy.
Hence, the same story as that of the Tower of Pisa seemed to be repeating itself.
The restoration process was also a delicate and complex challenge in this case: even
the slightest mistake could have ruined months of investigations, commitment and
especially the integrity of the historical structure. In-depth knowledge of the
characteristics of the site and preliminary tests were required in order to address the
priority of safeguarding the artistic value of the structure. When “actual” consolidation
work began, everything was being kept under strict control. Professional climbers
operated directly on the cliff using anchors and grouting, and a special mixture
of mortar was created with the support of experts from ICOMOS - the non-governmental
international organization dedicated to the conservation of the world's monuments
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- in order to minimize the impact of anchor heads.
Consolidation and restoration work was completed in 2006. It allowed for stabilization
of the Eastern Giant Buddha's back wall and niche, while the Western Giant Buddha's
niche was protected against water and rock falls. The reconstruction can now be
seriously considered. The Trevi Group worked in collaboration with important
international organizations and with art and history experts from all over the world.
It stabilized the remaining structure and took safety measures to facilitate future
archaeological investigations. This intervention proved extremely successful: UNESCO's
technicians praised the Trevi Group for its innovative technologies and expertise.
Today, in the Bamiyan Valley, the shadows of the Buddha statues inside the empty
but stable niches bear witness to how it is always possible to rescue something from
destruction. The Trevi Group committed itself to protecting a story, to rescuing a
form of art. This is a further demonstration that when the worlds of technological
innovation, dedication, high-level technical skills and internationally acknowledged
know-how meet, there is no challenge that cannot be overcome.
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5.
Chap.
In Conclusion...
What is the spark that makes a company an internationally appreciated and reputed
“great company”, like the Trevi Group?
The answer undoubtedly lies in the story we have told you. The story of a company
which has always met even the most difficult challenges, facing them with the
enthusiasm of those who know they can win. The enthusiasm for a mission we believe
in, but also the many efforts made by all the people who have showed their commitment
to the company. Real “teamwork” that involves carrying out investigations and
projects, but also good administrative and organizational skills. Because nothing can
be built without good “foundations”. Solid foundations, which the Trevi Group has
always had, communicating this strength through its daily work.
The Trevi Group stands out as a shining example of an Italian company, bringing to
the rest of the world its strength, its forward-thinking and its dedication to technological
innovation. The Trevi Group has developed a global reputation for excellence thanks
to its solid foundations.
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6.
Chap.
References and Websites
References
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Websites
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Pollack, J. (2011). The Empire State Building. http://goo.gl/sKpp1
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la storia. http://goo.gl/9bKmHX
Romagna Oggi. (2013). Dagli USA commessa da 18 milioni di dollari per il Gruppo
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History, Art and Engineering

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