Model Tests of Subsidence of the Reinforced Soil over Voids

Abstract

Geosynthetics have been used as reinforcement layers to bridge over underground voids or sinkholes 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 mm 3 (L×H×W) with 7 trapdoors at the bottom. The one of the trapdoors at the bottom of the contained 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 twodimensional (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+/2.

Application of a Geotextile in the Treatment of Post-Subsidence in Karst Areas

“…The trends of parabolic curves of vertical deflection of geotextile for different anchorage lengths are similar. Le et al [15] also found that the measured shape of the geosynthetic matched well with the parabolic curves. The greatest value for deflection exists at the center of the subsidence area.…”

“…To overcome these disadvantages, geosynthetic products have been increasingly used to create reinforced soil structures [10][11][12] and have been used as reinforcement layers to treat subsidence caused by sinkholes. A geosynthetic product acts as tensioned membrane that is combined with soil aching to support the upper soil mass [13][14][15][16], which has proven to be an effective alternative measure.…”

“…It was pointed out that the geocell mattress should spread beyond the void at least a distance equal to the diameter of the void. Le et al [15] found that the deformation of a geosynthetic basal reinforcement approximated a parabolic or circular curve by model tests of subsidence with reinforced soil over a void.…”