Applying Geophysical Methods for Site Characterization: A Case Study in Selangor, Malaysia

Abstract

Subsurface conditions play a critical role in the structural integrity of foundations. Traditional drilling methods often offer limited insights, creating a need for complementary techniques that provide more comprehensive subsurface imaging at lower costs and greater efficiency. This study integrates geophysical methods-specifically Seismic Refraction and Electrical Resistivity Imaging (ERI-to conduct a pre-foundation site assessment at MAHSA University in Bandar Saujana Putra, Malaysia. Geologically, the area is characterized by the Kenny Hill Formation, an Upper Paleozoic sedimentary sequence overlain by alluvial soils. Seismic Refraction was used to determine subsurface layering and material velocities, with geophones capturing refracted wave data to construct velocity and depth profiles. The ERI survey employed the Wenner and Schlumberger configuration to map resistivity variations, indicating soil composition and geological features. Interpretation of seismic and resistivity data revealed details on soil strength, weathering profiles, and rippability, enhancing site suitability assessment. The analysis identified three main material layers. The first layer, classified as Weathering Grade VI, consists of completely weathered material decomposed into soil, reaching a depth of about 6–9 meters. With a Weathering Grade V classification, the second layer is also considered rippable and extends beyond 15 meters in depth. Finally, denser material was found below 15 meters, classified as Weathering Grade IV; this layer is moderately weathered, still rippable, but approaching a marginal level. Results highlight the value of integrating geophysical methods in foundation engineering, offering improved reliability over conventional soil testing by delineating soil-rock interfaces and subsurface heterogeneities critical for foundation stability.