Evaluation of liquefaction-resistance of soils using standard penetration test, cone penetration test, and shear-wave velocity data for Dhaka, Chittagong, and Sylhet cities in Bangladesh

Abstract

The evaluation of liquefaction-resistance for saturated loose sandy and silty soils up to a depth of 20 m is an important component of geotechnical site characterization in an earthquake-prone region. In the present study, the standard penetration-test blow count (SPT-N), cone penetration test (CPT) tip resistance (qc), and shear-wave velocity (Vs) data of near-surface soils from Dhaka, Chittagong, and Sylhet cities were used to evaluate the liquefaction-resistance by a simplified procedure. At each site in the cities, the liquefaction-resistance is evaluated using a peak horizontal ground acceleration of 0.15, 0.20, and 0.25 g for a scenario earthquake of magnitude 7.5 (Mw). Then, the liquefaction potential index (LPI) is calculated for each site using the safety factors of liquefaction-resistance and thickness of liquefiable soil layers to predict the severity of liquefaction. The results indicate that sand boils (LPI > 5) and lateral spreading (LPI > 12) will be generated due to liquefaction in the Holocene saturated sandy and silty soils in Dhaka, Chittagong, and Sylhet cities. The evaluation of liquefaction-resistance using the SPT-N, qc, and Vs data shows considerable variation in the prediction of safety factor and LPI. Therefore, it is necessary to use two or more in situ test data to properly evaluate the liquefaction-resistance of soils for an area; and the simplified procedure needs to be used carefully. The results of the liquefaction-resistance of soils can be used to improve the ground condition in Dhaka, Chittagong and Sylhet cities for the construction of earthquake-resilient structures and future urban development.