Study On Coal Seam Floor Water Resisting Key Strata Instability And Water Inrush Risk

Coal seam floor water inrush is a kind of rock mass instability phenomenon under mining activities,which seriously threatens the safety of coal mine production.For a long time,scholars at home and abroad have made remarkable achievements in the deformation and destruction of shallow and horizontal seam floor,water inrush mechanism and water inrush evaluation,which have played an important guiding role in the safe mining of coal seams in confined water.However,with the increase of mining depth,these theories are gradually not suitable for deep seam mining.Therefore,theoretical analysis and numerical simulation facies are adopted in this paper.Combined with the method,the instability of water-proof seam floor and the risk assessment of water inrush from floor in deep coal seam are systematically studied.The specific research results are as follows:1.Through the analysis of geological conditions and hydrogeological conditions such as stratum,structure,aquifer and groundwater level recharge in the study area,it is determined that the water inrush source threatening the floor water inrush in Yangcheng Coal Mine is Ordovician aquifer,and the fracture structure also increases the probability of floor water inrush in three coal seams to a certain extent.2.Based on the thin plate theory of elasticity mechanics,the mechanical model of key aquifer stratum of coal seam floor is established,and the deflection variation law of the model is analyzed.Combined with Mohr-Coulomb strength criterion,the hydraulic criterion of coal seam floor inrush is deduced,which provides a theoretical basis for the instability of key aquifer and the establishment of evaluation index system of water inrush.3.According to the orthogonal experimental design,the numerical simulation of floor water inrush criterion under different mining conditions in Yangcheng Coal Mine is carried out,and the range analysis of the simulation results is carried out.The sensitivity order of each factor in floor water inrush criterion is determined,and the risk evaluation index of floor water inrush is determined in combination with the second chapter of this paper.4.Using principal component logistic regression analysis method,comprehensive evaluation method and water inrush coefficient method to determine the relevant weights of the main control factors of floor water inrush,and combining with vulnerability index method to establish the corresponding water inrush evaluation model.Through the evaluation of the comparison model,the results show that:the precision of comprehensive evaluation method>the precision of principal component logistic method>the precision of water inrush coefficient method.The comprehensive weighted vulnerability index model not only takes into account the sensitivity of the main controlling factors of floor water inrush,but also follows the objectivity of the original data.The evaluation results are more scientific and accurate,which can provide theoretical basis for safe mining in confined water of Yangcheng Coal Mine.