Seepage prevention of mining-disturbed riverbed

Abstract

Coal mining under a body of water introduces a potential risk of water inrush to the mine. Based on the practice of coal mining near the Jinsha river in Gansu province, China, and focused on the seepage prevention of the mining-disturbed riverbed, the surface movement, failure characteristics of the overburden strata, and water percolation induced by mining underneath the river have been investigated by means of in situ monitoring, physical modeling, and discrete element numerical simulation. A flexible anti-seepage scheme, Four Element Structure (FES), is put forward to protect the riverbed from seepage, and the structure can harmonize and buffer the mining-induced deformation of the surface land. Upward from the bottom of the riverbed, FES is composed respectively of: Reinforcement layer, which plays the roles of strengthening the riverbed, buffering the deformation, and enhancing the integrity of the riverbed; Bedding course layer, which prevents the anti-seepage layer from folding damage due to dislocation and sharpness in the riverbed, meanwhile it can absorb localized deformation; Anti-seepage layer, which is a major anti-seepage texture made by geo-membrane with the properties of water proof, a high strength, good flexibility and ductility; Protective layer, which covers the geo-membrane by a layer of precast reinforced concrete bricks to fix and protect the anti-seepage layer. In addition, treatment principles are proposed for reshipping of the river path in plane, the stream gradient along the longitude and the shape of cross section of the riverbed, and a comprehensive seepage prevention system is established.