Zoning of soil shear strength parameters (Case study: Kermanshah)

In order to know the site, obtaining soil strength parameters is necessary and at the same time costly and time-consuming. In this research, using 135 geotechnical boreholes drilled in Kermanshah, zonation of soil shear strength parameters (friction angle and cohesion) using ArcGIS software and ordinary kriging interpolation method (with spherical, exponential, and Gaussian semi-variograms), Up to a depth of 9 meters in three-meter intervals has been done and using the root mean square error (RMSE) and mean absolute error (MAE), the best model for predicting the characteristics has been selected. Based on the error evaluation indicators, the best variograms for zonation friction angle and cohesion at depths of 0 to 3 m is Gaussian, 3 to 6 m is exponential and 6 to 9 m are Gaussian and spherical, respectively. According to the results, mainly with increasing depth, angle of friction and cohesion (shear strength) has increased and the northern and southwestern parts of Kermanshah, compared to other regions, have soil with higher friction angle and lower cohesion (coarse-grained), and the northwestern parts of the city have clay and alluvial soils that the results are confirmed by the passage of the Qarasu river through this area and the location of the northern and southern regions of Kermanshah at the foot of the mountain.