Study On Overburden Rock Mining Effect And Water Gushing Of The Fourth Aquifer In 32 Mining Area Of Xutuan Coal Mine

After the completion of mining in 32 Mining Area of Xutuan Coal Mine in Huaibei,the water inflow in the goaf is stable at about 50m³/h,and the water inflow source is mainly the fourth aquifer,which increases the mine drainage and sewage treatment cost,and improves the mine production cost.Therefore,grouting treatment is needed,and the determination of water gushing channel is the key of treatment technology.Taking 32 Mining Area of Xutuan coal mine as the research object,based on the systematic collection and sorting of mine geology,hydrogeology and exploration drilling data,this paper comprehensively uses the methods of mathematical statistics,theoretical calculation and numerical simulation to analyze the engineering geology,hydrogeological characteristics and coal seam occurrence in the research area.The development characteristics of water conducting fracture zone in overburden of complete roof structure and fault roof structure are studied,and the damage effect of fault on the fourth aquifer basement under mining conditions is discussed.Combined with the fault development and geophysical exploration results,the water inflow channels in the study area are predicted and divided into types,which provides a basis for the water inflow control of the fourth aquifers in the area.The main achievements and understandings are as follows:（1）The distribution characteristics of lithology,thickness,unit water inflow and permeability coefficient of the fourth aquifer in 32 Mining Area are systematically analyzed.On this basis,the subjective and objective weights of each main control factor are determined by AHP method and entropy weight method respectively.The comprehensive weight of each main control factor is determined by multiplication synthesis normalization method,and then the water yield of the fourth aquifer in 32Mining Area is evaluated and divided by Arc GIS software.According to this,the four water bearing capacity of coal mine was divided into four levels:the stronger water rich area,the medium rich water area,the weaker rich water area and the weak rich area.（2）The engineering geological characteristics of overburden of 3₂coal seam in 32Mining Area are analyzed,and it is determined that the area belongs to medium hard overburden structure type.（3）Two engineering geological models of complete roof structure and roof structure with faults are established.Considering the factors of mining thickness and fault drop,the mining effect of overburden is numerically simulated,the development height of water conducting fracture zone of various models is obtained,The destructive effect of faults on the basement of the fourth aquifer is revealed,and the activation degree of faults with different fall is analyzed.（4）Based on the numerical simulation,theoretical calculation and the measured results of adjacent mining areas,the height distribution trend of overburden water conducting fracture zone in 32 Mining Area is comprehensively determined.And the thickness of residual water resisting layer before and after considering the influence of faults in 32 Mining Area is obtained.The fault strength index is selected as the prediction index to delineate the fault structure development area within 32 Mining Area.Combined with the development degree of fault structure and geophysical exploration results,the fourth aquifer water inflow channel is predicted,and two aquifer water inflow channel models such as fault activation type and the fourth aquifer basement fault failure type are established.Figure[46]Table[13]Reference[114]...