Correlating Ground-Penetrating Radar Data with Geotechnical Data

We investigated a significant correlation between Ground-Penetrating Radar (GPR) combined with down-hole seismic technique and geotechnical data (boring log and Standard Penetrating Test) to examine geophysical data as an important aid tool in interpreting geotechnical parameter. GPR data provide geotechnical engineers with continuous layering information, whereas down-hole seismic test (DHT) delivers geotechnical parameters such as Poisson's ratio σ, Young Modulus E, Shear modulus and Bulk moduli. By combining these data with boring log and standard penetrating Test (SPT) data, a comprehensive estimation about geotechnical parameters can be achieved. We conducted GPR measurement with 100 MHz shielded antenna in two profiles (inline and cross-line) centered at a borehole. We conducted also SPT to measure soil strength and boring to know the lithology. Intensive examination reveals that GPR technique should be applied to extend the meaning of geotechnical parameter value around and between boreholes. From case study at ITB site, we found some interesting result. Whereas both GPR and down-hole seismic data can reveal hard soils with SPT value of more than 60 corresponding to silty sand, GPR data can detect the interface between silty clay and clayey silt layers that cannot be detected from SPT. This study reveal the potential use of GPR technique as a tool for investigation of subsurface that can be elaborated to the exploration of shallow coal seams in subsurface as well to that of valuable minerals.