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

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 (q c), and shear-wave velocity (V s) 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 (M w). 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, q c, and V s 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.