Assessment of Liquefaction Potential Index for Sylhet City considering Maximum and Average Amplification Factor

Md. J. B. Alam; Shriful Islam; Nur M. R. Hoque; Shilpy R. Basak; A. I. Shuvo; S. K. Das

doi:10.37591/joge.v8i2.5426

Abstract

Soil liquefaction often occurs in saturated or partially saturated silty or sandy soil when an earthquake generates dynamic cyclic stress in the soil mass, reducing shear strength and stiffness. This study aims to assess the seismic soil liquefaction hazard potential for Sylhet City using shear wave velocity profiles of 49 boreholes. Factor of Safety (FOS) was evaluated taking into account shear wave velocity and maximum intensity of surface acceleration corresponding to Srimangal earthquake of magnitude 7.6. FOS maps with colour index based on maximum and average amplification were generated. The central-western part and central-eastern parts of the city show a minimum FOS of 0.31-0.8. Spatial distribution of clustered LPI values using GIS was analyzed considering a threshold value LPI of 5 for the liquefaction to be initiated for Sylhet City. The developed contour maps also depict the site-specific liquefaction intensity based on the LPI values of each borehole. The liquefaction potentiality of the city area varies from very low to low, low to high, and very high. Keywords: Liquefaction potential index, Shear wave velocity, Factor of safety, Cyclic stress ratio, Amplification factor.