GIS-Based Spatial Assessment of Preliminary Soil Bearing Capacity in Gapan City Using DPWH Geotechnical Data

This study evaluates the soil characteristics and spatial distribution of shallow soil bearing capacity in Gapan City, Nueva Ecija, to support preliminary geotechnical assessment and planning. Using secondary DPWH borehole records and QGIS-based Inverse Distance Weighted (IDW) interpolation, the research analyzes soil types and Safe Bearing Capacity (SBC) at 1.5m and 3.0m embedment depths. Findings show that soil bearing capacity improves by 15% to 40% as depth increases from 1.5m to 3.0m. At 1.5m, values range from 66.98 kPa to 110.214 kPa, whereas at 3.0m, values reach up to 127.68 kPa. The northern sector, including Gapan City barangays such as Pambuan and San Lorenzo, exhibits the lowest capacities at shallow depths. The resulting thematic maps classify Gapan City into low (65–74 kPa), moderate (74–92.9 kPa), and high (above 92.9 kPa) bearing capacity zones. The study concludes that deeper strata generally exhibited higher estimated bearing capacity values. These maps serve as a preliminary screening tool for engineers and planners, though the researchers emphasize that they do not replace the requirement for site-specific geotechnical testing for multi-storey or heavy infrastructure projects.