Enhancement of a seepage control facility of an earth-filled dam that has a concrete face and a cutoff wall

Abstract

Introduction. When a rockfill dam with a concrete face is constructed on the earth foundation, its seepage control facility is complemented by a cutoff wall and an apron. Together they represent a complicated integrated seepage control facility. The performance of an integrated seepage control facility gains relevance, which is proven by the experience in the operation of a number of dams, whose concrete faces and cutoff walls may be in the adverse stress state. Towards this end, the authors studied the stress-strain state (SSS) of an integrated seepage control facility. Materials and methods. The study was conducted at the Miaojiaba rockfill dam that has an integrated seepage control facility. This dam is 111 m high and 348 m long; its riverbed is about 45 m thick. Numerical modeling using the finite element method was performed to study the spatial SSS of this dam. Measurements of the dam displacements were taken to calibrate the finite element model. Results. The SSS of the dam was analyzed to develop two alternative structural designs of an integrated seepage control facility. As for the first design option, each element (the face, the cutoff wall, the apron) is made of concrete. The analysis of this option has shown that compressive and tensile stresses, arising in the cutoff wall, exceed the strength of concrete. Besides, the cutoff wall gets separated from the foundation. Within the framework of the second option, the cutoff wall is made of clay-cement concrete. According to the results of the analysis, this design option ensures the sufficient strength of all components of a seepage control facility. Conclusions. To ensure the strength of a seepage control facility that has a concrete face, a cutoff wall and a connecting apron, the cutoff wall and the apron should be made of less rigid materials.