International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 09 | Sep 2025
p-ISSN: 2395-0072
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Assessment of Seismic Liquefaction through detailed Seismic Study of Soil- A case study Saurabh Kumar1, R. Roshan2, Azhar Ali3 1Saurabh Kumar – Assistant Manager, KEC International Ltd., Mumbai, India 2R. Roshan - Assistant Manager, KEC International Ltd., Mumbai, India
Azhar Ali - Assistant Manager, KEC International Ltd., Mumbai, India ---------------------------------------------------------------------------***---------------------------------------------------------------------Abstract - Soil liquefaction has caused several damages in the past to lifeline and structures. Liquefaction is a phenomenon 3
where soils suffer loss in shear strength due to cyclic loading such as an earthquake. The mapping of liquefaction of soil can be done using seismic, geotechnical, and topographical parameters. Obtaining a suitable seismic parameter is a key challenge that can aid to qualitative mapping of Liquefaction potential of a soil stratum. This paper presents a comparative study conducted at a site in Gujarat to evaluate the liquefaction potential of soil using two different techniques, involving the usage of the obtained Peak Ground Acceleration (PGA). Bhuj (2001) earthquake was one of the most devastating earthquakes that occurred in Gujarat in recent years with a magnitude of 7.7. The site is 105 km from the epicenter of Bhuj (2001) earthquake for which attenuation relationship is incorporated, and the PGA is assessed using Linear Ground Response Analysis using the SPT information. Plasticity of soil plays a key role in determining the Liquefaction potential of the soil stratum. This paper devises a significant impact in the field of liquefaction assessment for soils with moderate to high plasticity and intends to add to the body of knowledge on liquefaction studies. Keywords: Liquefaction, Plasticity, Clays, Sands
1. INTRODUCTION The strength and serviceability of a structure determine its stability. Liquefaction can lead to ground subsidence, lateral spreads, disruption of vital services, and significant damage to infrastructure. Cyclic liquefaction is a phenomena whereby cyclic loading, like an earthquake, resulting in loss of its shear strength partially or completely.
2. LITERATURE REVIEW The first conventional method to assess liquefaction using the Standard Penetration Test (SPT) was the streamlined process put out by Seed and Idriss (1982) [1]. Although liquefaction was long thought to be limited to sandy soil deposits, a few observations made after many earthquakes showed that it may also occur in fine-content soils with medium to low plasticity. The Haicheng and Tangshan earthquakes in 1975 and 1976 caused silty sand to liquefy into slightly sandy silt soils. Wang (1979)[2] was the first researcher to point out this phenomenon and proposed a criterion that clayey soils could only be liquefiable if all three of the following conditions were met- percent of particles less than 0.005 mm < 15%, liquid limit (LL) < 35% and ratio of water content and liquid limit (wc/LL) > 0.9 (Wang, 1979 [2]; Seed and Idriss, 1982 [1]). This standard was termed as Chinese criteria due to its origin. Threshold-level plastic soils are generally immune to flow liquefaction failures and the ensuing deformation and strength loss. The study's findings led to the conclusion that the liquefaction response of soil can be defined by a specific range of the plasticity index and the water content to liquid limit ratio. The study categorized liquefaction response into susceptible, moderately susceptible, and non-susceptible classes. Bray and Sancio (2006) [3] reviewed previous works and defined a new set of PI and wc/LL range criteria. Boulanger & Idriss (2006) [4] categorized soils as “sand-like” and “clay-like” considering their plasticity index values. The importance of PI as a parameter for analyzing the liquefaction potential of saturated clayey soils was verified by Gratchev et al. (2006) [5] The correlation between Cyclic Resistance Ratio (CRR) and SPT-N value is presented Indian Standard Code 1893 (Part 1): 2016 [6] . It is one of the most simplified approaches to determine the liquefaction potential of silt and sand. SPT–N values is one of the most popular, oldest, and frequently used in-situ tests for the subsoil investigation because of its simplicity. Factor of Safety (FOS) is calculated to determine the likelihood of liquefaction. FOS is calculated using SPT-N. SPT-N is the most common parameter for the prediction of liquefaction. FOS is the ratio of CRR to the Cyclic Stress Ratio (CSR) using equation (1). CRR is considered the fundamental parameter for the estimation of liquefaction, which is mainly observed
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