The fracturing characteristics of rock mass of coal mining and its effect on overlying unconsolidated aquifer in Shanxi, China

Abstract

Due to coal mining taking place on a large scale in northern China, it is inevitable that wide-spread dewatering occurs in the aquifers overlying the resulting goaf. The purpose of this paper is to protect the groundwater of overlying unconsolidated aquifers. Based on physical model experiment, seepage experiments, and numerical simulation, this paper determines the patterns and distribution of the overburden rocks in the goaf, establishes the correlation between the fracture ratio and the hydraulic conductivity of the rock mass, and characterizes the groundwater flow pattern. The results show that (1) the residual fracture occurring ratio within the residual fracture zone is approximately 1.82 times that of the fracture compaction zone and 1.93 times that of the coal wall support zone; (2) the hydraulic conductivity of the rock mass in different parts of the goaf increases with increasing fracture ratio, the relationship of the two follows a power curve; (3) the predicted groundwater levels from numerical simulation is good fit with the measured and indicates that the hydraulic conductivities derived from seepage experiments are rational. We demonstrate how a laboratory-scale physical model can be used effectively to verify existing conceptual models in such a way that the impact of coal mining on groundwater resources can be predicted for similar regions.