Interaction between Groundwater and Rock Fractures under Stress and Seepage Based on Extractive Water Resource Utilisation

Abstract

In the fragile mining areas of western China, the contradiction between coal mining and water resource protection coexists prominently. Facing this issue, it is necessary to understand the dynamic relationship between mining-induced shear stress and groundwater seepage, as well as the fracture morphology of the overlying strata. In this study, the seepage characteristics of rough fractures within the rock mass are thoroughly investigated, with an emphasis on studying the effects of shear stress and seepage erosion. This research is carried out through seepage experiments and 3D fracture morphology scanning, and the research results are mainly as follows: (a) Rocks with higher shear strengths show less fluctuation in changes in fracture morphology and seepage velocity. (b) The permeability of sandstone and concrete fractures is inversely proportional to the shear stress. The layering of coal greatly limits seepage through the fractures and the permeability of coal is about one-tenth of the permeability of sandstone and concrete under the same conditions. (c) The mechanism of erosion damage to the rock by water-force coupling is the result of the shear and extrusion generated by rock fractures and the transport of rock particles. Changes in fracture erosion and seepage characteristics brought about by the damage will mutually promote and intensify the erosive effect of water force. (d) The degree of change in fracture morphology (fracture damage) under the same conditions is coal > concrete > sandstone. There are differences in the response of different types of rock to the shear stress–seepage erosion, but all show obvious changes in fracture damage and seepage characteristics.