Clay soil porosity estimation using seismic P- and S-wave velocities along Isfahan Metro Line 2

Abstract

To study how the soils, respond to an earthquake, seismic waves are frequently utilized. The purpose of this work is to build the porosity graphs based on the geotechnical parameters of the soils and forecast the porosity of shallow clay soils using seismic wave velocities that analyze the dynamic features of the soil. Compressional (P) and shear (S) wave velocities, seismic velocity ratio, Poisson ratio, bulk modulus, and shear modulus are the factors used to calculate porosity. In this work, porosity values are calculated using grain and dry densities of core samples taken from different boreholes within the study region, and bulk modulus, shear modulus, and Poisson ratio are calculated using P- and S-wave velocities obtained by utilizing the seismic-refraction method, as well as porosity values. The research region is in Iran; Isfahan Metro Line 2 and mostly consists of clay, silt, sand, and gravel deposits. Based on the values of the Poisson ratio, seismic P-wave velocity, seismic velocity ratio (V_p/V_s), and the stiffness of the clay soils, the data of the clay soils in the region were individually sorted. These characteristics were used to create novel multi-parameter relationships between clay soil porosity, seismic velocities, shear modulus, and the Poisson ratio. Using the error norm approach, the errors in the parameters utilized for each relationship were identified. The error norm technique's findings show that the shear wave velocity and shear module have the lowest error when calculating porosity. Therefore, it is advised to estimate porosity of shallow clay soils using the given correlations. These relationships can be used to assess the porosity of clay soil and to determine if the soil's pores are saturated with liquid.