GIS-based soil bearing capacity zonation maps for the Dhaka metropolitan development plan (DMDP) area, Bangladesh

This study develops soil bearing capacity zonation maps for the Dhaka Metropolitan Development Plan (DMDP) area in Bangladesh. A total of 360 borehole records from different locations within the region were compiled and analyzed. The mapping was carried out in ArcGIS 10.5, utilizing the Ordinary Kriging interpolation method. This research has developed 4 (four) shallow foundation bearing capacity zonation maps for the DMDP area at 1.5 m and 3.0 m depth and 2 (two) pile capacity zonation maps at 12.0 m and 20.0 m depth based on SPT-N₆₀ values.Precast pile size of 12″×12″ was used for the calculation of pile capacity at 12.0 m and 20.0 m depth, respectively. The accuracy of the zonation maps was evaluated by comparing estimated pile capacities at 12.0 m with pile load test results at seven locations. The analysis yielded an RMSE (Root Mean Square Error) of 5.76%, MAE (Mean Absolute Error) of 4.61, a coefficient of determination (R²) of 0.6, and a correlation coefficient of 0.77. The allowable bearing capacity in the study area is significantly influenced by soil type and shallow soil conditions. The bearing capacity zonation maps will assist geotechnical designers in the initial selection of the site and depiction of encountered strata. The map conserves time and resources by providing a fundamental overview of the preliminary foundation design, covering the estimated cost.