Production of maps for bearing capacity of the shallow foundation in Baghdad city using SPTs and MATLAB software

Abstract The standard penetration tests are considered one of the most important tests to determine the bearing capacity of the soil. In this research, a set of objective maps and equations were produced to estimate the bearing capacity of shallow foundations based on the results of SPTs conducted in Baghdad Governorate. The work includes drilling 213 wells 10 meters deep below the surface of the earth, and conducting three standard penetration tests (SPT) on each well at depths of 1.5, 6 and 9 m. The bearing capacity of the shallow foundations in the city of Baghdad was determined using the MATLAB program after the SPT values were corrected. Then several polynomial equations with multi-order interpolation are proposed to estimate the bearing capacity of the foundation, but the first-order polynomial equation is considered simpler and straightforward. Moreover, the root mean square error (RMSE) of all the proposed polynomial equations is almost the same. Thematic maps show the difference in the carrying capacity of shallow foundations across the total ground of Baghdad Governorate with respect to different depths. Then, a comparison was made between the calculated and estimated values of the foundation’s bearing capacity, where the results showed a discrepancy of 30% at a confidence level of 95%.