A Study on the Effect of Field Procedure Corrections of SPT- N Values on the Liquefaction Resistance of the Subsoil Strata along the Coastline of Visakhapatnam

Abstract

The effects of liquefaction are often catastrophic, so evaluating the liquefaction potential of the subsoil strata is necessary to characterize their behaviour under dynamic loading, particularly earthquakes. Several laboratory tests are in use to evaluate the liquefaction potential of the soils. However, for improved accuracy, data from field tests are extensively being used to determine the liquefaction resistance of the ground. Over the years, several SPT- N-based methods were developed to assess the liquefaction resistance of sub-soils. Nevertheless, several studies reported the liquefaction potential of the soils without taking into consideration the field procedure corrections of standard penetration resistance (N), which may have a significant influence on the liquefaction evaluation. Hence, in the present study, the effect of SPT N field procedure corrections on the liquefaction resistance of the subsoil at the ten study areas selected along the coastline of Visakhapatnam is investigated. The Factor of Safety (FoS) against liquefaction is evaluated as per IS 1893(2016) and Idriss & Boulanger (2008) methods based on corrected and uncorrected standard penetration resistances and different input ground motions. The corresponding liquefaction potential indices (LPI) are determined from the Iwasaki et al. (1978) method to analyse the damage potential of the liquefaction. The study indicated that the field procedure corrections substantially affect the liquefaction resistance, as upon applying corrections to SPT N, the subsoil profiles at most study areas showed susceptibility to liquefaction, which are otherwise non-liquefiable.