Study On Prediction,Evaluation And Application Of Faults Hydraulic Conductivity

The mining of coal seam is restricted by geological structure and hydrogeological conditions,especially the existence of water-conducting fault,which complicates mine hydrogeology,not only brings adverse influence to the efficient production of mine,but also increases the possibility of mine water inrush.Mine hydrogeologists have always attached great importance to the study of faults hydraulic conductivity,but due to its complexity,the problem has not been well solved,so the further study of faults hydraulic conductivity is of great significance to the prevention and control of mine water damage.By means of theoretical analysis,laboratory test and other comprehensive methods,this paper conducts a detailed study on coal faults hydraulic conductivity.Using the principle of similar material simulation and based on the displacement and seepage experiment,three samples with different lithologic ratios were selected,through the displacement and seepage experimental equipment designed by ourselves,the indoor simulation experiment of fault pressure,groundwater pressure and lithological composition of fault zone is designed to simulate fault hydraulic conductivity,and the influence characteristics of fault pressure,water pressure and argillaceous content on fault conductivity are obtained;taking into account the experimental results of fault hydraulic conductivity,the research status of fault hydraulic conductivity and sealing property,7 factors affecting fault conductivity were determined,including lithologic docking relationship,shale smear,fault mechanical properties,water pressure,plastic deformation of mudstone,fault zone argillaceous content,and rock cementation;Based on the simulation experiment of fault hydraulic conductivity,the influence factors and the research of fault hydraulic conductivity mechanism,the current research methods of fault hydraulic conductivity and fault closure are referred to,in view of the seven influencing factors,seven methods were proposed to predict and evaluate fault hydraulic conductivity jointly by using shale gouge ratio(SGR),shale smear factor(SSF),lithologic juxtaposition diagram,fault closure index,fault zone cementation degree analysis,mudstone plastic deformation index,and water-rock stress action index,the fuzzy analytic hierarchy process(AHP)was used to determine the weight of each index,and two comprehensive prediction and evaluation models of fault conductivity were established,namely,fault side water conductivity index C and fault vertical water conductivity index V.Taking Jining no.2 coal mine as an application,the fault development characteristics and fault development mechanism are emphatically analyzed according to the geological characteristics of the research area,and the faults are divided into two stages;the borehole stress relief method is used to measure the stress of three groups of rock in the study area,based on the mathematical model of fault hydraulic conductivity prediction and evaluation,the fault hydraulic conductivity prediction and evaluation of 21 faults in the study area were carried out,the results show that the fault's overall hydraulic conductivity is poor,only a few of them are good;it is verified by the actual exposure that the verification results are consistent with the evaluation results,indicating that the fault conductivity evaluation model is accurate.The study of this paper has guiding significance for mine water prevention and control in coal resources mining in the region with developed structure.