Empirical Correlation between Shear Wave Velocity (Vs) and Uncorrected Standard Penetration Resistance (SPT-N) for Dinajpur District, Bangladesh

In seismic analysis, shear wave velocity ("V" _"s" ) is a valuable parameter for measuring the site effect of earthquake microzonation. Various methods have been explored to measure this key factor directly. Since measuring shear wave velocity directly is time consuming and expensive, researchers in various regions have been attempting to update empirical relationships between shear wave velocity ("V" _"s" ) and other soil geotechnical properties such as SPT blow count, depth, vertical effective stress and so on. Geophysical tests associated with direct methods are not feasible in developing countries like Bangladesh, so the indirect method is more important. Due to the location of a fault line nearby, the Dinajpur district has previously undergone anomalous earthquakes. As a result, site characterization is important for enhancing seismic design considerations. Focused on an indirect approach, this paper mainly aims to propose a general correlation between shear wave velocity and standard penetration number in 13 upazilas of Dinajpur district for four soil categories (“all soils”, sand, clay, and silt). Finally, an approach was developed to find the overall correlations for the Dinajpur district by combining all of the data. The regression coefficient ("R" ^"2" ) values were observed to vary in between 0.04416-0.6134 for “all soils”, 0.0593-0.668 for sand, 0.5911-0.7149 for clay and 0.5547-0.6794 for silt. The correlations obtained in this study can be used for seismic hazard analysis in both the study region and other areas with identical soil strata.