This seminar presentation discusses soil liquefaction, including when it occurs, susceptible soil types, how it works, examples of where it has occurred, and methods to mitigate it. The presentation contains 18 slides covering an introduction to liquefaction, when it occurs due to reduced effective stress or cyclic loading, soils susceptible to it, how seismic waves cause densification and increased pore pressure, examples like the 1964 Niigata earthquake in Japan, techniques to mitigate it like vibro-compaction, dynamic compaction, and stone columns, and conclusions about analyzing and remediating liquefaction-prone sites.

1. A SEMINAR ON
SOIL LIQUEFACTION
Presented by: Guided by:
SHAIK AHMED JAWAD Dr. ABU SAYEED MOHAMMED
USN:1HK14CV044 HOD
8 Sem Civil Department Civil Department
SLIDE NO 1

2. CONTENTS
 Introduction
 When does it occur?
 Soils susceptible to liquefaction
 How it works?
 Places where soil liquefaction had occured
 Clip On San Francisco Earthquake 1906
 How to mitigate Soil Liquefaction
 Conclusion
 References
SLIDE NO 2

3. What is Soil Liquefaction?—Soil liquefaction is a
phenomenon whereby a saturated or partially
saturated soil substantially loses strength and stiffness in
response to an applied stress, earthquakes, etc.
It is a major cause of structural damage during
earthquake
INTRODUCTION
SLIDE NO 3

4. WHEN DOES IT OCCUR??
When the effective stress of soil is reduced to
essentially zero, which corresponds to a complete
loss of shear strength
Initiated by
– Monotonic Loading
– Cyclic loading
SLIDE NO 4

5. SOILS SUSCEPTIBLE TO LIQUEFACTION
• The soils whose factor of safety is less than 1
• Cohensionless soil or non-plastic silt soils
• Any loose soil that has the tendency to get
compressed once sheared
• Saturated loose state of soil which can generate
vital pore water pressure on application of load
SLIDE NO 5

6. HOW IT WORKS??
When the seismic waves pass through the soil, the
vibrations cause the individual grains in the soil to
– move around and
– re-adjust their positions
This ultimately results in decrease in the volume of
the soil mass as
– the grains pack more tightly together and thereby
the porosity also decreases
SLIDE NO 6

7. HOW IT WORKS??
Thus, the pore water pressure increases such that it
counteracts the gravitational pull on the soil particle
Eventually, Soil Liquefaction occurs.
SLIDE NO 7

8. PLACES WHERE SOIL LIQUEFACTION
OCCURED
Niigata Earthquake, Japan in 1964
Alaska Earthquake in 1964
San Francisco in 1906
Calaveras Dam, California in 1918
Great Hanshin Earthquake in 1995
SLIDE NO 8

9. Niigata Earthquake, Japan in 1964 SLIDE NO 9GOOGLE

10. Alaska Earthquake in 1964 SLIDE NO 10GOOGLE

11. SLIDE NO 11YOUTUBE

12. HOWTOMITIGATELIQUEFACTION
a. Improving soil propertiesby:
 Vibro-compaction
 Dynamic compaction
 Compactinggrouting
 Stonecolumns
b. Lowering ground watertable:
SLIDE NO 12

13.  Vibro-compaction :-Vibro-compaction involvesthe useof a
vibrating prone that can penetrate granular soil to depths of
over 100 feet. The vibration of the prone cause the grain
structure to collapse thereby densifying the soil surrounding
theprone.
SLIDE NO 13
GOOGLE

14.  Dynamic compaction:- Densification by dynamic compaction is
performed bydropping aheavy weightof steelor concreteinagrid
patternfromheightsof 30to 100feet
SLIDE NO 14
GOOGLE

15.  Compaction grouting:-Compaction grouting is a technique
wherebyaslow-flowing water/sand/cementmixis injected into
loose sand under high pressure. Grout does not get mix with
thesoilbut formsabulb thatcompactand densifythesoil
SLIDE NO 15
GOOGLE

16. Stonecolumn:-Stonecolumnsare
columns of gravel constructed in
the ground. Stone columns can
be constructed by the vibro-
compaction method. In steel
casing 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.
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SLIDE NO 16 GOOGLE

17. CONCLUSION
The analysis is carried out on four liquefaction susceptible sites in VIZ., Kutch,
Bhuj, Delhi and Lucknow and the suitable remediation is designed for each site.
The two sites with less deep active zone around 6m are remediated through
dynamic compaction with specifications as above mentioned.
The other two sites with active zone extending up to around 18m is
remediated through vibro stone columns with specifications.
Sites are being improved in its bearing capacity and the settlement is also
reduced by remediations.
SLIDE NO 17

18.  Analysis of Liquefaction Prone Area in India and Its Remediation
(IJRASET)
 Japan Society of Civil Engineers, 1995, "Preliminary Report on The
Great Hanshin Earthquake, January 17,1995”
 Fang, Hsai-Yang, Foundation Engineering Handbook, 2nd ed., 1990
 Kawasumi-Hirosi (editor), General report on the Niigata earthquake of
1964, 1968
 Kramer, Steven L., Geotechnical Earthquake Engineering, Publ. Prentice
Hall, 1996
REFERENCES
SLIDE NO 18

19. SLIDE NO 19