Influence of high salt mine water storaged in underground reservoir of coal mine on Groundwater

Taking the underground reservoir of Lingxin coal mine as the engineering background,the two factors affecting the adjacent aquifer were analyzed during the construction and operation of underground reservoir in the coal mine.First,the overburden fracture caused by the repeated mining will lead to the aquifer,which will have the first impact on the groundwater resources in the mining area.Second,in the process of high salt mine water injected into the underground reservoir,due to the effect of concentration gradient,the mineral ions will mainly diffuse along the fracture channel,which may have a secondary impact on the underground water resources in the mining area.These two factors are closely related to whether the mining fracture forms a through seepage channel.Based on the above analysis the evolution law of the fracture network and the characteristics of the seepage channel of overburden rock under the condition of repeated mining were analyzed through the solid liquid coupling similarity model test,and based on the discrete element method,the distribution characteristics of fracture network and the influence of repeated mining on the upper protected aquifer were further analyzed.The results show that the fractures in overlying strata in the goaf are interconnected and extend to the K4 aquifer under repeated mining and have little influence on the K3 aquifer after the completion of mining in No.1 mining area.Combining the characteristics of fracture network obtained by similarity simulation and numerical calculation,the seepage and diffusion processes of highly mineralized mine water in mining induced fracture network were simulated by using the Open GeoSys multi-field coupling numerical simulation software,and the pollution risk of mine water to the upper protected aquifer in the sealed reservoir after mass separation was analyzed.The results show that under the condition of water injection,only a small amount of mine water will be diffused into the K3 aquifer within 50 years when the highly mineralized mine water fills the gap space between the goaf and the K4 and K3 aquifers.