Settlement of soil

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Settlement of soil
GFS Univerzitet u Novom Sadu
WUS Austria

• By Sloboda Danijela,
• Vlaovic Goran,
• Zavisic Bojan and
• Merkovic Ivan

Teachers Dr. Petar Santrac Dr.
Ruza Ostrogonac
Date of presentation 21.12.2007.
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Settlement of soil (how and why it
happens) Any structure built on soil is subject
to settlement. Some settlement is inevitable and,
depending on the situation, some settlements are
tolerable. In designing a structure it is
commonly assumed that the foundation will not
move. Correspondingly, if cracks appear in the
structure it is assumed that the foundation did
move and that this is the sole cause of
cracking. As building loads are applied to the
ground an "immediate" settlement occurs as a
result of instantaneous compression of the soil.
Most immediate settlement may be accommodated
within the structure as it is built, and
fortunately much of the differential movement
occurs at this stage. Under certain conditions,
however, fine-grained soils will continue to
compress under constant load for many years. This
long-term compression is called "consolidation"
settlement and is caused by the squeezing out of
water from the pores in the clay. Differential
settlement occurs for a number of reasons -
Local variations in soil compressibility, -
Variation in thickness of compressible soil, -
Differences in footing sizes and pressures, -
Variation in applied loads, - Overlapping
stresses, - Differences in depth of embedment of
footings. -Soil Permeability -Soil Drainage
-Load to be placed on the soil -History of
loads placed upon the soil (normally or
over-consolidated?) -Water Table Types of
Settlement There are three basic types of
settlement uniform settlement, tilt, and
non-uniform settlement
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Types of
geotechnical testing The most common types of
geotechnical testing used to evaluate the modulus
of the soil are penetration tests such as the
Standard Penetration Test (SPT) or the Static
Cone Penetration Test (CPT). The standard
penetration test (SPT) is the most commonly used
in situ test. However, cone penetration test
(CPT) is becoming increasingly popular as an in
situ test for site investigation and geotechnical
design. There are number of testing but we are
going just to name some of them -analytic and
numeric methods - - Lines of equal vertical
stress caused by surface loads
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To decreases future settlements we have to
compacted soil, and here are some of machines
which we can do that
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Settlement of structures -The Palace of
Fine Arts in Mexico City, for example, built
sometime between 1900 and 1934 it was a
magnificent and strongly built structure. It was
built on grade, level with the square and other
buildings nearby.  But because of loose sand
permeated with water in the subsurface, the
massive structure sunk more than 340, 8 cm into
the ground!  (Luckily, it settled evenly
minimizing structural damage.)   Believe it or
not, in the 1960's the building moved again. 
This time it moved 365, 76 cm up!  The weight of
skyscrapers being built around the Palace had
pushed the subsurface water and soil around
sufficiently to raise the building.
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- In Winnipeg, an extension to a church was built
over an area in which the trees were cut down
immediately before construction. The floor slab
for the addition, which rested directly on the
ground, was heaved 15, 24 cm in two years, giving
an annoying discontinuity between the old and new
sections. -It is common in many of the heavy clay
regions of Canada for shallow foundations to move
up or down by several inches.
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Solution for settlement of soil -One of the
solutions is so called floating foundation. The
word "floating" is used in its literal sense.
When a body floats in water, it displaces a
volume of water the weight of which is equal to
the weight of the floating body. The Post Office
Building in Albany, New York, was one of the
pioneer North American buildings to be so
founded. There are now some Canadian buildings
floating on the soil beneath them, notably a fine
multi-storey building in Ottawa founded on clay.
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-examples of pile foundation and there range of
max load
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Pisas Tower This is the monument that, among
the others of the "Piazza dei Miracoli", stirs
the imagination of everybody, from the old to the
young. Firstly we like to give you some
information and events regarding its long
history. The construction of this imposing mass
was started in the year 1174 by Bonanno Pisano.
When the tower had reached its third storey the
works ceased because it had started sinking into
the ground. The tower remained thus for 90 years.
It was completed by Giovanni di Simone, Tommano
Simone (son of Andreo Pisano), crowned the tower
with the belfry at half of 14th century. The top
of the Leaning Tower can be reached by mounting
the 294 steps which rise in the form of a spiral
on the inner side of the tower walls. This very
famous work is of Romanesque style, and as
already stated dates back to the year 1174.
Cylindrical in shape it is supplied whit six open
galleries. This monument is not lacking in
elegance and lightness due to the arcades and
open galleries between one storey and another.
Although it can be considered a real masterpiece
of architecture, this monument is mostly famous
for its strong inclination. Regarding this
inclination it can be safely stated that it is
undoubtedly due to a sinking of the ground right
from the time of its construction. Therefore, the
assumption of those who desire to imagine that
great tower was built inclined is entirely
without foundation.
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-It is one of the most famous buildings in the
world. It has been built before hundreds years
ago. When three tops were over, they started to
swoop, so the tower started to list. Engineer,
who ganged its loch, says that the tower all the
time tends, it lurches for 2,5cm.Stalian expect
that the tower won't tumble.
Even today the great mass continues to sink very
slowly. It is a question of about 1 mm. every
year. Since nobody can state with mathematical
security that this sinking will continue in the
future at the present yearly rate, without its
ceasing, remedies by means of adequate measures,
based on scientific studies and projects, are
under consideration. In the meantime supervision
with instruments of very high precision is
continuously being carried out.
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These procedures and associated theoretical
considerations of soil action constitute the
modern science of Soil Mechanics. The proper
application of the results of such scientific
studies now enables the foundation engineer to
design a foundation for any given combination of
loads on even the most unpromising soil, as also
upon soils that have not caused problems when
utilized in more pragmatic ways.