A field evaluation of peat settlement on road infrastructure: Integrating 2D electrical resistivity tomography (ERT) and geotechnical instrumentation

Abstract

Peat soils within Sarawak region pose significant challenges to road embankment construction due to their high compressibility, low shear strength, and spatial variability. This study employs 2D Electrical Resistivity Tomography (ERT) as a rapid, non-invasive technique to evaluate peat settlement behavior along the Sebuyau–Lingga (Package B1) section of the Sarawak Second Trunk Road (SSTR). Multiple ERT profiles were acquired across the alignment to delineate peat thickness, identify subsurface variability, and characterize soft ground conditions. In-Peat geomechanical monitoring data were integrated to correlate and validate resistivity interpretation. Results show a clear relationship between resistivity values and measured settlement magnitude, with low-resistivity zones corresponding to highly compressible peat layers. Field settlement observations further support these correlations. The integrated geophysical– geotechnical approach enhances the rapid detection of critical soft ground sections, improves investigation efficiency, and supports more informed design and construction decisions in peat-dominated terrain. Additionally, the resistivity method effectively differentiates between hard-filled embankment materials, peat, and clay, providing valuable subsurface characterization for construction control.