The presentation deals with various ground improvement techniques which can be employed on a liquefiable foundation of any structure.

1. “Case Studies on Ground Improvement
Solutions to Mitigate Liquefaction”
PRESENTED BY,
H.C.SUMANTH
18GACV3003
3RD SEMESTER M.TECH
GEOTECHNICAL ENGINEERING
UVCE, BENGALURU

2. CONTENTS
• INTRODUCTION
• LITERATURE REVIEW
• GROUND IMPROVEMENT SOLUTIONS
• CASE STUDIES
• CONCLUSIONS
• REFERENCES

3. INTRODUCTION
• An earthquake is the shaking of the Earth resulting from
the sudden release of energy in Earth’s lithosphere that
creates seismic waves.
• Despite of significant development in technology and
engineering services, earthquakes cause major destruction
of various types of structures and cause havoc to the
society.
• Phenomenon where strength and stiffness of a loose,
saturated cohesionless soil is reduced by earthquake
shaking is known as Liquefaction.
• During Liquefaction, pore water pressure increases in
undrained shearing process causing a reduction in
effective stress which in turn reduces the shear strength.

4. Figure 1. Liquefaction flow failure at the lower San Fernando
Dam Due to the 1971 San Fernando earthquake

5. Figure 2. Failure of Upstream slope of lower san Fernando
dam due to liquefaction of granular hydraulic fill

6. Figure 3 Uplifted sewage manhole during the 2004 Niigata earthquake
Figure 4 Liquefaction induced failure of apartment and bridge during
2004 Niigata earthquake

7. • Liquefaction failure due to earthquake causes
1.Catastrophic failures
2.Failure of important utility structures like dam, bridge,
highways etc.
3.Failure of underground pipelines and services and
many more..
• Hence, there is a need to mitigate the potential hazard
caused by liquefaction of sand and silty sand soils by
adopting suitable mitigation techniques.

8. LITERATURE REVIEW
• Ronald D Andrus et al., 1995: Soil densification method
is generally considered highly reliable, and the standard
remedial measure against liquefaction. It reduces the void
space of the soil, thereby decreasing the potential for
volumetric change that would lead to liquefaction.
• Mohtar et al.,2013: Ottawa sand premixed with 10%
bentonite suspensions showed a large increase in
liquefaction resistance. Further with addition of 0.5%
Soidum Pyrophosphate (SPP) viscosity dropped to a
value that allowed delivery of the bentonite into the sand
matrix through permeation.

9. • Huang et al.,2014: Currently anti-liquefaction research is
faced with three main problems:
1. How to achieve non-disruptive mitigation of liquefaction
risk at developed sites susceptible to liquefaction, especially
under vulnerable structures.
2. How to achieve liquefaction mitigation in large areas at low
cost
3. How to combine liquefaction mitigation with environmental
friendliness and low-carbon economy
• Madan Kumar Annam et al., 2015: The presence of liquefiable
soil does not mean that one has to abandon the site or install
deep foundations. In seismic zones with liquefiable soils,
ground improvement technique provides technically sound and
cost effective solutions.

10. GROUND IMPROVEMENT SOLUTIONS
1. Densification
Figure 5 Vibro-Compaction
Figure 6 Vibro-Replacement

11. Table 1. Densification methods

12. 2. Solidification
Table 2. Solidification methods

13. 3. Drainage
Table 3. Drainage methods

14. 4. Dewatering
Table 4. Dewatering methods

15. 5. New methods:
a. Passive site stabilization : Colloidal silica grouting,
bentonite suspension grouting.
b. Bio-cementation
c. Induced partial saturation: Air Injection, Biogas
d. Mitigation using tire chips

16. CASE STUDIES
Case study 1: A School Building, Noida, UP, India
• Soil investigation at the proposed school building site
revealed that loose to medium fine sand exists upto a depth
of 9m below the existing ground level
• The sand layer is susceptible to liquefaction
• Project falls under Seismic Zone IV
• Vibro compaction technique was used to densify the sand
and improve N value (preferably more than 20 as per
design)
• Plate load test was performed at site to assess the treated
ground.

17. Figure 7. Graph showing performance of vibro compaction

18. Figure 8 Graph showing load intensity v/s settlement

19. Case Study 2: Product Packaging Unit, Babrala,
UP, India
Figure 9 Typical borehole log at Babrala

20. • Site was prone to liquefaction as it falls under seismic
Zone IV.
• Stone columns were installed for conveyer belt and
transfer tower foundations.
• Combination of stone columns and vibro compaction was
used for control room foundations
Figure 10 Combination of vibro compaction and stone columns

21. Figure 11 Pre and Post SPT comparision

22. Case Study 3: Power Plant at Goindwal Sahib,
Punjab, India
• A huge coal based power plant was proposed to be built
which consisted of boliers, electro static precipitators,
switch yards and power house building.
• Soil at this site was, 1.5 to 2m of silty sand. Followed by
fine sands up to 30m about 6% fines content.
• N value was 10 up to depth 4-5m (Loose sand).
• N value ranged from 15-25 up to 15m (Medium dense)
• N value was above 25 beyond 15m ( Medium dense to
dense sand).
• Loose sand was susceptible to liquefaction.
• Vibro Compaction technique was proposed to mitigate
liquefaction.

23. Figure 12. Twin Vibrators in action

24. Figure 13. The difference in levels achieved (about 1m) as
a result of vibro compaction

25. Figure 14. Pre and Post CPT results at ESP area

26. CONCLUSIONS
• The presence of liquefaction susceptible soil does not
mean that one has to abandon the site or install deep
foundations.
• In seismic vulnerable zones, ground improvement
solutions provide technically sound and cost effective
solutions.
• Vibro-replacement and Vibro-compaction are the basic
methods of increasing the density. These methods can be
adopted and cross checked by conducting SPT, CPT and
Plate load tests.
• New methods like passive site remediation using low
viscosity colloidal silica and bentonite suspensions can be
used to treat the liquefaction susceptible soil beneath
existing structure

27. REFERENCES
[1] C. S. El Mohtar, A. Bobet,M. C. Santagata, V. P. Drnevich, C. T. Johnston (2013),
“Liquefaction Mitigation Using Bentonite Suspensions”, Journal of Geotechnical
and Geoenvironmental Engineering.139:1369-1380.
[2] IS 1893-2016 (Part 1), “Criteria for Earthquake Resistance Design of Structures,”
Bureau of Indian Standard, New Delhi, India.
[3] Kramer, S.L. (1996), “Geotechnical Earthquake Engineering”, Pearson Education,
First Indian reprient 2003.
[4] Madan Kumar Annam, Raju V R (2015), “Ground improvement solutions to mitigate
liquefaction: case studies”, Keller Asia, The Master Builder.
[5] Maithili K L.,(2017), “A Discussion of Liquefaction Mitigation Methods”,
International Research Journal of Engineering and Technology (IRJET), ISSN: 2395-
0056
[6] Ronald D. Andrus, Riley M. Chung (1995), “Ground Improvement Techniques for
Liquefaction Remediation Near Existing Lifelines”, Building and Fire Research
Laboratory, National Institute of Standards and Technology, Gaithersburg, US
department of commerce.
[7] Seed H.B., Idriss, I.M (2001), “Simplified procedure for evaluating soil liquefaction
potential”, Journal of Geotechnical Engineering. Div., ASCE 97 (9), 1249-1273.

28. [8] The Japanese Geotechnical Society (2004), “Remedial measures against soil
liquefaction” (Revised version), Balkema.
[9] Towhata I (2008), “Mitigation of liquefaction-induced damage”, Geotechnical
earthquake engineering. Springer, Berlin, pp 588–642
[10]Vahab Besharat (2012), “The Methods of Remediation of Existing Underground
Structure against Liquefaction”, 15th World conference on earthquake engineering,
Lisboa.
[11]Yu Huang, Zhuoqiang Wen. (2015), “Recent developments of soil improvement
methods for seismic liquefaction mitigation”, Natural Hazards, Springer 76:1927–
1938.

29. THANK YOU