Model Tests of Subsidence of the Reinforced Soil over Voids

Geosynthetics have been used as reinforcement layers to bridge over underground voids or sinkholes and to support upper soil mass. In such applications, the geosynthetics (acting as tensioned membranes), together with the soil arching, sustain the stability and mitigate the subsidence of the soil mass. An experimental study was conducted to investigate the subsidence of the soil mass induced by the permissible deformation of the geosynthetic reinforcement. The study was conducted in a container with dimensions of 875×625×50 mm³ (L×H×W) with 7 trapdoors at the bottom. One of the trapdoors at the bottom of the container can be lowered to induce differential settlements. The soil was simulated by aluminum bars that have various diameters but uniform length of approximately 50 mm. The aluminum bars were intentionally used as the substitutes of soil particles to simulate the two-dimensional (2D) situations. A layer of geotextile was place underneath the "soil fill" to serve as the reinforcement. During the tests, the trapdoor was lowered and the induced movements of the "soil particles" and the deformation of the geosynthetic layer were recorded and quantified by the photogrammetry methods. The subsidence profiles at different elevations were developed. It was found that subsidence was decreased hyperbolically in the vertical direction and the lateral influence range appeared to be bounded by the active soil zone (i.e., within the two planes of 45+φ/2).