Mapping of Soil Bearing Capacity in Butuan City, Agusan Del Norte, Philippines using Geographic Information System

Abstract

Soil bearing capacity is critical for the success of infrastructure projects and foundational design. This study utilizes Geographic Information System (GIS) software to generate soil bearing capacity maps for Butuan City, Agusan Del Norte, Philippines, based on Standard Penetration Test (SPT) borehole logs from various sectors. The study addresses the challenge of limited geotechnical data in urban areas by providing a reliable method for mapping soil bearing capacity using sparse data. Thematic maps were produced using interpolation techniques: Inverse Distance Weighted (IDW), Empirical Kriging, and Spline. Results indicated soil bearing capacity values ranging from 58.09 kPa to 87.40 kPa at 1.5 m and 165.53 kPa to 238.31 kPa at 3.0 m depth. IDW interpolation emerged as the most accurate method, confirmed by high Pearson’s coefficient values and lower root mean square error (RMSE), mean absolute error (MAE), and Relative Mean Error (RME) metrics. The integration of GIS and IDW interpolation fills a significant knowledge gap, enabling the creation of detailed and dependable soil maps. These maps are crucial for geotechnical and civil engineers to perform preliminary assessments and make immediate decisions in urban planning.  Regular updates are recommended as new Standard Penetration Test (SPT) data becomes available to ensure map accuracy and relevance.