Liquefaction potential mapping of Newtown-Rajarhat area, Kolkata, India, using deterministic and reliability analysis

摘要

The region of Newtown-Rajarhat is undergoing a massive industrial and residential growth and as the area has layers of sand and silt mixed with clay and organic matter, it is essential to determine its liquefaction potential. In this study, the deterministic methods proposed by Boulanger and Idriss (Evaluating the potential for Liquefaction or Cyclic failure of silts and clays, 2004; CPT and SPT based Liquefaction Triggering Procedures, 2014) were utilized to evaluate the liquefaction potential of the study area using 101 borehole data for earthquake magnitudes (M-w) of 6 and 7. The parameter uncertainties were identified and a reliability analysis was performed to represent the liquefaction potential in terms of reliability index and probability of liquefaction. Using First-Order Second-Moment (FOSM) method, contour maps were prepared for depths of 7 and 15 m for both the earthquake magnitudes. It was concluded that the study area is most vulnerable to liquefaction at a depth of 7 m in the regions of Newtown, Rajarhat and Sector V.