A Comprehensive Evaluation of Void Detection in Mechanically Stabilized Earth Walls

Mechanically stabilized earth (MSE) walls are extensively used in highway projects due to various advantages over traditional gravity wall systems. They may, however, exhibit instability due to loss of backfill materials, rebar corrosion, inadequate reinforcement, insufficient drainage, and other factors. Traditional destructive testing for void detection can compromise the structure’s integrity, resulting in costly repairs. This study introduces an integrated approach of nondestructive testing (NDT) for void detection on two MSE walls in Mississippi using uncrewed aerial vehicles (UAVs), light detection and ranging (LiDAR), ground-penetrating radar (GPR), and spectral analysis of surface waves (SASW). High-resolution UAV photos detected surface deterioration. GPR test results revealed voids adjacent to both MSE walls extending up to 2.4 m depth. SASW results revealed gaps in the dispersion curves at void locations. Additionally, the average surface wave velocity contour generated from the SASW results showed increased velocity in the presence of voids compared to the surrounding areas. SASW and GPR results were consistent with the site investigation results. However, GPR provided more detailed information on the depth of voids, and SASW identified some voids not detected by GPR. After repair, LiDAR monitoring detected no further movement in either of the MSE walls. The study highlights that while individual NDT techniques are effective, the integrated approach using GPR, SASW, LiDAR, and UAVs enhances accuracy in void detection and establishes a more comprehensive framework for infrastructure monitoring, which enables opportunities for early problem detection, leading to reduced repair costs and overall improvement of long-term structural performance.