Extended Abstract Volume of International Geotechnical Engineering Conference on Sustainability in Geotechnical Engineering Practices and Related Urban Issues, September 23-24, 2016, Mumbai, India.
Liquefaction Susceptibility of Soils in Kutch Region
Majid Hussain i) and Ajanta Sachanii) i) Ph.D. Research Scholar, Civil Engineering, IIT Gandhinagar, Palaj, Gandhinagar, 382355, India. Email:
[email protected] ii) Assistant Professor, Civil Engineering, IIT Gandhinagar, Palaj, Gandhinagar, 382355, India. Email:
[email protected]
Keywords: Liquefaction Potential, SPT, Simplified Procedure, Kutch Region, Gradation.
EXTENDED ABSTRACT Liquefaction is the loss of strength and stiffness in saturated soils under dynamic loading conditions. Earthquake induced liquefaction is a common phenomenon in regions with soil strata comprising of loose to medium dense sand/silt and shallow water table. Liquefaction susceptibility of a given soil strata depends on various factors: initial stress state, seismic load and duration, soil gradation, density, particle size & shape, drainage conditions, stress history, ageing, soil fabric, particle cementation etc. Extensive liquefaction was observed during Bhuj Earthquake 2001 including damage in dams, embankments, ports, bridges, buildings and pipelines over a radius of 400 km from the epicenter. Kutch Earthquake 1819 also resulted in widespread liquefaction including sand boils, lateral spreading of embankments, ground cracking and water spouts etc. Hengesh et al. (2002), Sitharam et al. (2001), Sitharam et al. (2004) reported widespread liquefaction in Bhuj Earthquake 2001. Detailed geotechnical studies regarding liquefaction susceptibility of soils in the region is still unexplored. Liquefaction damage in Kutch region during past earthquakes requires in-depth experimental studies including evaluation of liquefaction potential. Present study aims to conduct an extensive experimental investigation of soils from Kutch region. 32 soil samples from different locations at different depths were collected from the region, and detailed geotechnical investigation of all soil samples was carried out. Location of sample collection sites using GPS Visualizer is shown in Fig 1.Ten soil strata including five earthen dam sites within 200km from the epicenter (Bhuj earthquake 2001) were selected for the current study. These five dams experienced damage
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due to liquefaction and related failures during; Chang Dam, Suvai Dam, Fathegarh Dam, Tappar Dam and Shivlakha Dam. Samples were collected at depth ranging from 0.5m to 2.5m from the ground surface. Garmin GPS etrex10 was used to measure coordinates of each site during the sample collection. Geological investigation of all ten sites was also carried out including onsite determination of in-situ bulk density, in-situ water content, and depth of water table. Water table depth at the time of sample collection was observed to be in the range of 0.5m to 2.5m, or greater in few locations. Experimental results obtained from basic geotechnical investigation of 32 samples are presented in Table 1, which was further used to determine the liquefaction susceptibility of Kutch region. Tsuchida (1970) provided two range of grain size distribution (GSD) for liquefiable soils: a) Range A: Boundaries for most liquefiable soils, b) Range B: Boundaries for potentially liquefiable soils. Fig 2 shows GSD of soils collected from Kutch region along with range A and range B. 25 soil samples were observed to have non-plastic fines ranging from 9% to 81%. 15 soil samples showed silt content less than 20%, and only 6 soil samples exhibited clay content. Fig 2 shows that GSD of 24 soil samples appeared inside the Range A and 25 soil samples inside the Range B. GSD of 7 soil samples appeared outside the Range A & Range B indicating the soil samples not being susceptible to liquefaction. Most of the soils from Kutch region were classified as silty sand (SM). In the present study, liquefaction potential of 32 soil samples collected from different sites and different depths of Kutch region was determined for 7.5M & 8.5M earthquake using Simplified Procedure (Youd et al. 2001). SPT data was used to determine the liquefaction potential, which is the ratio of CRR (Cyclic Resistance
Majid Hussain
Extended Abstract Volume of International Geotechnical Engineering Conference on Sustainability in Geotechnical Engineering Practices and Related Urban Issues, September 23-24, 2016, Mumbai, India.
Ratio) and CSR (Cyclic Stress Ratio). Table 1 shows liquefaction potential of Kutch soil samples for seismic events of 7.5M and 8.5M in terms of factor of safety (FOS). Fig 3 and Fig 4 exhibit liquefaction potential of Kutch region at a depth of 1.5m for 7.5M & 8.5M earthquake respectively. High liquefaction potential (low FOS) was observed for all the locations for 7.5M earthquake. With increase in magnitude from 7.5M to 8.5M, the liquefaction susceptibility of soil strata at 1.5m was observed to be increased. For 7.5M earthquake, most of the Kutch soil strata were observed to be susceptible to liquefaction except Chobari and Banniari at 2.5m depth. Soils with loose to medium density were found to be more susceptible to liquefaction such as Khadir, Kharoi, Suvai Dam. FOS values for 8.5M earthquake were found to be decreased at a given site indicating more susceptibility to liquefaction. Most of the failures were reported on the upstream slopes of the dams despite being empty at the time of earthquake 2001. This was because of the shallow foundation were located on saturated soils, which liquefied and caused large deformations. On the upstream foundation soils, liquefaction manifested itself as longitudinal cracks, a common failure pattern in all the dams. At present situation, these dam sites (Chang Dam, Suvai Dam, Fathegarh Dam, Tappar Dam and Shivlakha Dam) were determined to be susceptible to liquefaction, as shown in Table 1. Suvai dam was found to be at the most critical situation for liquefaction in future earthquakes. Other dams also exhibited critical situation for liquefaction at most of the depths (Table 1). Liquefaction susceptibility was not considered in the original design of these earthen dams, which led to the severe damage in these dams due to liquefaction. In the remaining five locations, water spots & sand boils were reported during earthquake 2001. Oriented fissures and intervening cracks spreading over ground surface were observed within 12m wide zone at Kharoi, south of Manfarra village (Singh et. al 2005). Results from the present experimental study of these sites were observed to be in accordance with the reported failures during the earthquake 2001. Liquefaction susceptibility study based on GSD & Simplified Procedure (Youd et al. 2001) exhibited high liquefaction potential of soils in
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most of these sites. The experimental findings from this study regarding geotechnical properties & liquefaction potential of Kutch Region could be further used to mitigate the liquefaction effects in Kutch region in future earthquakes.
Fig.1. Map showing sample collection sites of Kutch Region
Fig.2. GSD of soils collected from Kutch Rgion at different depths ranging from depth of 0.5 m to 2.5 m
Majid Hussain
Extended Abstract Volume of International Geotechnical Engineering Conference on Sustainability in Geotechnical Engineering Practices and Related Urban Issues, September 23-24, 2016, Mumbai, India.
Table 1. Liquefaction Potential of Kutch Region for 7.5 and 8.5 magnitude earthquake
Sample Name Chang Dam S1 (Location1) S2(Location 2) S3(Location 2) Kharoi S4 S5 S6 Suvai Dam S7 S8 S9 Fatehgarh Dam S10 S11 S12 Chobari S13 S14 S15 Khadir S16 S17 S18 Tappar Dam S19 S20 S21 Bodharmora S22 S23 S24 Banniari S25 S26 S27 S28 Shivlakha Dam S29 S30 S31 S32 Abstract ID:[Type here]
Depth (m)
Silt %
Clay %
0.5 0.5 1.5
11 15 17
6 3 2
0.5 1.5 2.5
13 9 11
5 3 2
0.5 1 1.5
21 19 14
7 5 3
0.5 1.5 2.5
61 42 20
38 3 2
0.5 1.5 2.5
42 42 36
2 7 5
0.5 1.5 2.5
17 22 9
2 3 2
0.5 1.5 2.5
24 14 14
18 14 10
0.5 1.5 2.5
21 46 57
8 19 23
0.5 1.5 2 2.5
81 68 26 13
2 27 6 8
0.5 1.5 2 2.5
25 9 18 50
4 2 7 22
Void Water Dry content density γd ratio (e) w% kN/m3 23ᴼ 27.94' N 70ᴼ 25.606' E 18.7 15.0 0.75 10.1 15.69 0.66 14.0 15.70 0.67 23ᴼ 28.367' N 70ᴼ 23.330' E 3.3 16.01 0.64 2.6 16.90 0.55 2.1 16.00 0.64 23ᴼ 36.428' N 70ᴼ 29.821' E 5.2 17.03 0.54 4.6 14.37 0.82 11.3 13.55 0.93 23ᴼ 41.369’ N 70ᴼ 48.057’ E 18.0 17.17 0.55 14.1 15.53 0.69 20.0 15.45 0.71 23ᴼ 30.722' N 70ᴼ 20.881' E 13.3 17.51 0.51 17.9 16.96 0.57 35.6 17.57 0.51 23ᴼ 50.82' N 70ᴼ 14.39' E 2.6 15.94 0.64 2.4 16.82 0.55 1.0 16.96 0.54 23ᴼ 15.017' N 70ᴼ 07.586' E 13.3 17.36 0.51 17.3 16.39 0.59 22.9 17.67 0.49 23ᴼ 20.634' N 70ᴼ 11.501' E 5.8 17.71 0.48 14.6 14.27 0.86 21.5 12.26 1.16 23ᴼ 24.299' N 70ᴼ 09.910' E 6.3 13.37 1.01 23.5 14.59 0.85 12.4 16.26 0.62 10.7 17.60 0.50 23ᴼ 24.659' N 70ᴼ 35.128' E 2.1 14.43 0.83 4.3 14.88 0.78 9.3 16.37 0.61 19.9 13.40 0.96
Majid Hussain
SPT N
FOS, 7.5 M
FOS, 8.5 M
14 10 16
0.42 0.66 1.02
0.33 0.51 0.78
16 4 6
1.03 0.35 0.44
0.79 0.27 0.34
16 14 1
0.48 0.40 0.14
0.37 0.31 0.11
NA 23 16
NA 1.22 0.49
NA 0.94 0.38
30 NA 30
2.57 NA 2.30
1.98 NA 1.77
10 2 4
0.74 0.35 0.38
0.57 0.27 0.29
14 16 27
0.64 0.53 1.35
0.49 0.40 1.04
14 16 2
1.20 1.21 1.16
0.92 0.93 0.90
2 NA 14 27
0.34 NA 1.08 2.37
0.26 NA 0.84 1.82
14 23 23 16
0.67 0.92 1.15 0.63
0.51 0.71 0.89 0.48
Extended Abstract Volume of International Geotechnical Engineering Conference on Sustainability in Geotechnical Engineering Practices and Related Urban Issues, September 23-24, 2016, Mumbai, India.
C:\Users\Meer\Desk top\Work \PhD\Testing\Data Files\A rcGIS plots\.ptmp55985\fig_1.5_7.5.jpg
C:\Users\Meer\Desk top\Work \PhD\Testing\Data Files\A rcGIS plots\.ptmp55985\fig_1.5_8.5.jpg
Fig.3. ArcGIS plot of Kutch Region at 1.5m depth for 7.5M
Fig.4. ArcGIS plot of Kutch Region at 1.5m depth for 8.5M
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5) Sitharam, T.G., Govindaraju, L. and Murthy, B.S., 2004. Evaluation of liquefaction potential and dynamic properties of silty sand using cyclic triaxial testing. Geotechnical Testing Journal, 27(5), pp.423-429 doi: 10.1520/GTJ11894 6) Srivastav, S.K., 2001, October. Bhuj earthquake of 26th January, 2001—some pertinent questions. In International Conference on Seismic Hazard with Particular Reference to Bhuj Earthquake of January 26 (pp. 3-5). 7) Tsuchida, H., “Evaluation of liquefaction potential of sandy deposits and measures against liquefaction induced damage.” Proceedings of the annual seminar of the Port and Harbour Research Institute, 1970, (3-1)-(3-33)(in Japanese) 8) Youd, T.L., Idriss, I.M., Andrus, R.D., Arango, I., Castro, G., Christian, J.T., Dobry, R., Finn, W.L., Harder Jr, L.F., Hynes, M.E. and Ishihara, K., 2001. Liquefaction resistance of soils: summary report from the 1996 NCEER and 1998 NCEER/NSF workshops on evaluation of liquefaction resistance of soils. Journal of Geotechnical and Geoenvironmental Engineering, 127(10),pp.817-833.doi:10.1061/(ASCE)1090-02 41(2001)127:10(817)
Majid Hussain
