Numerical Analysis of Embankments Supported by Geosynthetics over Drilled Shafts in Karst Terrains

This paper presents a new method to remedy a common sinkhole problem in karst terrains by using geosynthetics over drilled shafts to support an embankment. Numerical analysis using FLAC^2D software was conducted to verify the effectiveness of this method. In the numerical analysis, foundation soil, rock, and a drilled shaft wall were assumed to be elastic while embankment fill was assumed to be linearly elastic-perfectly plastic with a Mohr-Coulomb failure criterion. A geosynthetic layer above the drilled shaft wall was modeled using cable elements. The construction of the embankment was simulated in three stages. The numerical results include the settlement at the base of the embankment, the tension in the geosynthetic layer, and the axial force in the drilled shaft. A parametric study was conducted to investigate the effects of the void size and the tensile stiffness of geosynthetic. The numerical analysis demonstrated that this proposed method could be effective in maintaining the stability of the embankment over the sinkhole. This paper presents a preliminary study using geosynthetics and drilled shafts to mitigate the embankment over a small sinkhole. Further study is under way to investigate embankments over large sinkholes with multiple drilled shaft walls.