Soil liquefaction occurs when saturated, loose soils lose strength and behave like a liquid due to increased pore water pressure caused by seismic activity like earthquakes. This can damage structures through loss of bearing capacity, lateral spreading, sand boils, and settlement. Methods to reduce liquefaction risks include avoiding susceptible soils, deep foundations, soil improvement techniques like vibro-compaction and stone columns to densify soils, and designing liquefaction-resistant structures.

1. SOIL LIQUEFICATION
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2. CONTENTS
 INTRODUCTION
 OBJECTIVE
 MECHANISM OF SOIL LIQUEFICATION
 TYPES OF LIQUEFICATION
 EFFECTS OF LIQUEFICATION
 METHOD TO REDUCE LIQUEFICATION
 CONCLUSION
 REFERENCES

3. INTRODUCTION
 Liquefaction is the phenomena when there is loss of strength in saturated and cohesion-less soil
because of increased pore water pressures and hence effective stress is reduce due to dynamic
loading.
 During liquefaction the water pressure become high enough to counteract the gravitational pull
on the soil particles and effectively float or suspend the particles.
 Then soil particle move freely with respect to each other. due to this the strength of soil
decreases and the ability of a soil deposit to support foundations for buildings and bridge is
reduce.
What is soil liquefaction:-

4. OBJECTIVE
• To understand the liquefaction.
• The process that causes the soil to collapse and liquefy during an earthquake.
• Which soil are most susceptible to this occurrence.
• To find out which soil are strong on their own or could be combined with another soil to
make it more stable during an earthquake.
OBJECTIVE

5. ( Soil before liquefaction )
Loosely packed grains
of soil are held
together by friction.
Pore spaces filled with
water.
( Soil after liquefaction )
Shaking
destabilizes the
soil by increasing
the space
between grains
and soil flow like a
liquid

6. TYPES OF LIQUEFACTION
Flow liquefaction :-
Flow liquefaction is a phenomenon in which the static
equilibrium is destroyed by static or dynamic loads in
a soil deposit with low residual strength. It occurs
when the static shear stresses in the soil exceed the
shear strength of the liquefied soil.
Cyclic mobility:-
• Cyclic mobility is a liquefaction phenomenon,
triggered by cyclic loading, occurring in soil
deposits with static shear stresses lower than the
soil strength.
• Deformation due to cyclic mobility develop
incrementally because of static and dynamic
stresses that exist during an earthquake.

7. EFFECTS OF LIQUEFACTION
The ground can liquefy and lose its ability to support structure.
The ground can slide down very gentle slopes. It is mainly caused by cyclic
mobility. Lateral spreading causes damage to foundations of buildings, pipelines,
railway lines and cause shaking at pile due to increased lateral loads.
Loss of bearing strength:-
Lateral spreading:-
Lateral spread at budharmora ( Bhuj ,2001)

8. Sand boil :-
Sand-laden water can be ejected from a buried liquefied
layer and erupt at the surface to form sand volcanoes. The
surrounding ground often fractures and settles.
Flow failures:-
Flow failures are the most catastrophic ground failures
caused by liquefaction. These failures commonly
displace large masses of soil laterally. Flows develop in
loose saturated sands or silts on relatively steep slopes.

9. Ground oscillation :-
Where the ground is flat or the slope is too gentle to allow lateral displacement, liquefaction at depth
may decouple overlying soil layers from the underlying ground, allowing the upper soil to oscillate
back and forth and up and down in the form of ground waves. These oscillations are usually
accompanied by opening and closing of fissures fracture of rigid structures such as pavements and
pipelines.
Flotation:-
Light structure that are buried in the
ground(like pipeline sewers and nearly
empty fuel tanks) can float to the
surface when they are surrounded by
liquefied soil.
( Manhole ) ( Lifted up manhole )Settlement:-
Liquefied ground reconsolidates during an earthquake, the ground
surface may settle and the underlying liquefied soil become more
dense.

10. METHODS TO REDUCE LIQUEFACTION
 Avoid liquefaction-susceptible soil :-
The first possibility is to avoid construction on liquefaction susceptible soil.
 Build liquefaction-resistant structures:-
It may be possible to make the structure liquefaction resistant by designing
the foundation elements to resist the effects of liquefaction . Structure that
possesses ductility, has the ability to accommodate large deformations,
adjustable supports for correction of differential settlements
 Shallow foundation aspects:-
• It is important that all foundation elements in a shallow foundation are
tied together to make the foundation move or settle uniformly, thus
decreases the amount of shear force induced in the structural elements
resting upon the foundation.
• A stiff foundation mat is a good type of shallow foundation. Which can
transfer loads form locally liquefied zone to adjacent stronger ground.
Mat foundation

11. Deep foundation aspect
Liquefaction can cause large lateral loads on pile
foundations. Piles driven through a weak,
potentially Soil layer to a stronger layer not only
have to carry vertical loads form the superstructure,
but must also be able to resist horizontal loads and
bending moments induced by lateral movements if
the weak layer liquefies. Piles of larger dimensions
and/or more reinforcement can achieve sufficient
resistance

12. Soil improvement techniques against liquefaction:-
The main objective of soil improvement techniques used for reducing
liquefaction hazards is to large increases in pore water pressure during
earthquake shaking by improving the strength, density, and drainage
characteristics of soil.
Vibro-compaction :-
Vibro-compaction involves the use of a vibrating prone
that can penetrate granular soil to depths of over 100
feet. The vibration of the probe cause the grain
structure to collapse thereby densifying the soil
surrounding the probe.

13. Dynamic compaction:-
Densification by dynamic compaction is performed
by dropping a heavy weight of steel or concrete in a
grid pattern form heights of 30 to 100 feet.
Compaction grouting:-
Compaction grouting is a technique whereby a
slow-flowing water/sand/cement mix is injected
into loose sand under high pressure. Gout does
not enter soil but forms a bulb that compact and
densify the soil by forcing it to occupy less space.

14. Stone column:-
Stone columns are columns of gravel constructed in the ground. Stone columns can be
constructed by the vibro-compation method. In this approach the steel casing is driven into the
soil and gravel is filled in from the top and tamped with a drop hammer as the steel is
successively withdrawn.

15. CONCLUSION:-
• It can clearly be concluded that the ill effects caused by liquefaction have
devastating damages to structures built on liquefied soils. Hence the various
methods in which the severity of damage as a result of liquefaction can be
reduced.
• The behavior of soils under the influence of loading forces and soilwater
interactions

16. REFERENCES:-
• International Journal of Advanced Research in Basic Engineering Sciences and Technology (IJARBEST)
Parametric Study on Liquefaction ofAleru River Sand G. S. Kalyani, Assistant Professor, Department of
Civil Engineering., CMR Institute of Technology, Medchal,Telangana (India).
• Youd, T. L., and Hoose, S. N. (1978). "Historic ground failures in northern California triggered by
earthquakes." U.S. Geological Survey professional paper 993.
• Liquefaction and Deformation of Soils and Foundations Under Seismic Conditions Ricardo Dobry
Rensselaer Polytechnic Institute, Troy, NewYork.