Correlation between N-SPT value and shear wave velocity for clayey soil

Abstract

Shear wave velocity (Vs) is an important parameter for tunnel design to evaluate seismic site classification and earthquake hazard at a site. Unfortunately, determining in situ shear wave velocity for large areas is expensive and takes a long time. To overcome these problems, a correlation between the standard penetration test (N-SPT) and Vs is made in order to facilitate predicting Vs from the N-SPT value. N-SPT data were obtained from a total of 41 boreholes ranging from 40 to 85 m in depth. Shear wave velocity was obtained from seismic downhole tests and seismic refraction. The correlation between N-SPT and Vs in this study has a coefficient of regression (R2) value of 0.901. The correlation in this study is validated using normal consistency ratio, comparison between Vs predicted and Vs measured and a scaled error percent graph. The correlation in this study can be used as a predictor to estimate shear wave velocity for initial design before a survey is conducted.