Liquefaction potential assessment of the DMDP area of Bangladesh using CPT-based methods

For the last few decades, for the liquefaction susceptibility assessment of a location, Standard Penetration Test (SPT) based methods have been generally practiced. In this research, the liquefaction potential of Dhaka Metropolitan Development Plan (DMDP) area has been analyzed using three existing Cone Penetration Test (CPT) based methods. CPT (CPTu and SCPT) data have been collected from 546 locations of the DMDP region covering 1530 square kilometer area and have been analyzed to assess the liquefaction potential. Bangladesh is located in the junction of Indian and Eurasian plate, which makes this country vulnerable to earthquakes. A magnitude 7.5 earthquakes and Peak Ground Acceleration (PGA) value of 0.21 g at the surface have been used to evaluate the liquefaction susceptibility of the region using the three CPT-based techniques and another CPT-based technique has been employed to evaluate the liquefaction susceptibility of the region using variable surface PGA based on Modhupur scenario. Liquefaction potential maps have been proposed and compared for these four methods. It has been found that more than 60% of the study area falls within the LPI range which indicates moderate to relatively high liquefaction vulnerability. The liquefaction susceptibility of the three methods has been found to be in agreement and possible reasons of deviation in any particular method have been explained. Also, Ishihara 1985 proposed LPIISH has been estimated and compared with Iwasaki’s LPI values. It has been observed that the difference in results using LPI and LPIISH are not significant. The seismic microzonation and liquefaction analyses will help engineers, planners and relevant professionals to get prior idea about the seismic vulnerability of any part of the DMDP region and take measures beforehand to avoid any damaging consequences.