Geotechnical Engineering Journal of the SEAGS & AGSSEA ISSN 0046-5828
Vol. 51 No. 4 December 2020
CPT & SPT Tests in Assessing Liquefaction Potential
Ripon Hore, Sudipta Chakraborty, M. R. Arefin, and M. A. Ansary
ABSTRACT: The purpose of this research is to estimate the earthquake induced liquefaction potential of selected reclaimed areas of Dhaka city based on both Cone Penetration Test (CPT) and Standard Penetration Test (SPT). CPT and SPT data have been collected from ten (10) selected reclaimed areas of greater Dhaka city. The filling depth of the reclaimed areas varies from 1.5 to 13.5 m from the existing ground level (EGL). The values of peak ground acceleration (amax) and the magnitude (M) have been taken as 0.15g and7.5 respectively for the liquefaction analyses. The range of SPT-N, Cone tip resistance (MPa), local friction (kPa) and friction ratio varies between 1~42, 0.17~18.58, 0~273.2 and 0~9.34 respectively of the ten (10) selected sites of Dhaka city. Liquefaction potential has been estimated based on both CPT and SPT data. It has been observed that in reclaimed areas of Dhaka city especially for the locations reclaimed by dredged soil up to a filling depth of 1.5 to 4.5m there is high probability of liquefaction occurrence. In most of the cases, liquefaction zone for CPT have been observed in two different depth zones. On the other hand, liquefaction zone for SPT have been observed in only one zone. The highest value of Liquefaction Potential Index (LPI) for CPT and SPT are 21 (Bramangaon) and 28 (Purbachal) respectively. The lowest value of Liquefaction Potential Index for CPT and SPT are 3 (Kawran Bazar) and 1 (Kawran Bazar) respectively. The low liquefaction potential zone value has been found along the center and north south alignment of Dhaka City. The high potential zone has been found in the outer periphery of the study area.
KEYWORDS: Liquefaction potential, Soil profile, CPT, SPT, Cone tip resistance, Sub soil characteristics.
