Utilizing shallow seismic refraction in defining the geotechnical properties of the foundation materials: A case study at New Minia City, Nile Valley, Egypt

Abstract

The main objective of this paper aims to estimate the geotechnical parameters necessary for engineering constructions. For this purpose, thirty flat seismic refraction profiles were carried out in the study area northeast of New Minia City to describe the geotechnical properties of the subsoil for construction purposes. Both compressional (P) and shear (S) waves were detected and interpreted. The results show that the near surface section of the study area consists of two layers, the first layer of soil (sand from recent deposits), traversed by the second layer (sand and fragments of limestone) and changed laterally into fossiliferous limestone layer. Additionally, a number of engineering parameters for the second layer, such as elastic moduli (Poisson's ratio, bulk's modulus, rigidity modulus and Young's modulus), competence scales (material index, concentration index, stress ratio, and density gradient) and bearing capacity (ultimate and allowable) are determined. It was found that, the P-wave seismic velocities range from 2800 to 4500 m/s and the S-wave seismic velocities range from 1600 to 2750 m/s. Also, concluded that the values of Concentration Index, Material Index, Density Gradient, and Stress Ratio are ranging from 4.8 to 11.1, −0.053 to 0.603, −0.819 to −0.59, and 0.11 to 0.357, respectively. High difference between these two values reflects lithological, structural and textural variations occurred in rocks existed in the investigated area.The seismic velocity values and engineering parameters indicate that the bedrock at northwest and southeast of the study area have low competent rock quality, while the rest of the area have high competent rock quality. So, the suggested area for construction activities was about 9,489,876 m2 from total area 11,770,966 m2.