Application of MASW and ERT methods for geotechnical site characterization: A case study for roads construction and infrastructure assessment in Abu Dhabi, UAE

Abstract

In this study, the active multichannel analysis of surface waves (MASW) and the electrical resistivity tomography (ERT) were applied in Abu Dhabi City for road site characterization. The objectives were to detect the bedrock topography, to identify the weakness zones and to evaluate the nature of the soil. Forty-eight lines of MASW and three profiles of ERT were conducted in the study area. The shear waves velocity (Vs) values show that surface and very near-surface materials having very low Vs values (<180 m/s) and encountered as a thin continuous layer and in others as isolated lenses at 4.0 m to 5.0 m in depth. In general, the surface sediment materials in the studied area related to earth and infill material (loose to a very loose sediments) material except the top soil layer in some places. The cone penetration test (CPT) and standard penetration test (SPT) values confirmed the variations in rigidity suggested by the velocity models (N-value 5 and 8). Low shear wave velocities (180–360 m/s) and low CPT/SPT value encountered from the surface to 6.0 m depth were found to be related to less-consolidated soil. Below the top layer, the soil becomes stiffer with shear wave velocities between (360–750 m/s) and SPT value greater than 50. The highest shear wave velocity (Vs >750 m/s) was encountered at depth of 17 m and extends to the penetration depth of about 20 m. This deepest layer correlated to denser bedrock. Furthermore, the inverted resistivity models generally show that the resistivity values in the study site are low. However, three main distinguished resistivity zones were revealed across all profiles in the study area. The results of both MASW and ERT were compared and integrated, providing a good image of the soil properties and bedrock, and their reliabilities were verified with borehole data.