UTILIAZTION OF GEOPHYSICAL AND SEDIMENTOLOGICAL STUDIES IN THE ESTIMATION OF THE SUBGRADE SOIL IN BURAYDAH CITY, KINGDOM OF SAUDI ARABIA

With the continuous increase in population and economic and vital activities in Saudi Arabia and the entire world, there has become a significant increase in the construction activities. So, an appropriate investigation was carried out to assess the geotechnical parameters to verify the suitability of Buraydah area for the urban extension using shallow seismic refraction technique and sedimentological studies. For this purpose, fifteen seismic refraction spread and fifty nine sediment samples conducted in the study area. The sedimentological study includes; grain size analysis, to evaluate the textural parameters and statistical measurements to describe the depositional pattern of the studied sediments in the area. The statistical parameters include; graphic mean size varying from (-1.7ϕ) to (0.44ϕ), the sorting (σI) ranges from (1.3ϕ) to (2.2ϕ), the skewness (Sk) ranges from (-0.08ϕ) to (0.97ϕ), and the kurtosis (Kg) ranges between (0.57ϕ) to (2.2ϕ). In addition, this study was supported by microscopic analysis. Thefoundation material indices of shallow seismic refraction technique show that thecalculated values of Poisson’s ratio that founding within all layers throughout the study area is (0.24), the calculated material index values is (0.05) andthe estimated concentration index values is (5.2). The ultimate bearing capacity values of the surface layer where the values are ranged between 0.09 Kg/cm2 and 136 Kg/cm2, the second layer ranged from 2.87 Kg/cm2to 185 and the third layer values are ranged between 1.9 Kg/cm2 and 185 Kg/cm2.