Simulation And Vulnerability Evaluation Of The Influence Of Fault On Water Inrush From Coal Seam Floor In Panjiayao Coal Mine

Existing research shows that more than 80%of water inrush from coal seam floor is caused by faults.Therefore,it is very important to study the influence of faults on water inrush from coal seam floor.The existing evaluation models partially consider the influence of fault scale,but the influence of dip angle is rarely mentioned.In addition,the weight of each factor in the model mostly adopts constant weight,which can not reflect the influence of sudden change of index value,which weakens the control effect of a factor to a certain extent.Therefore,this paper focuses on the problem of water inrush from the coal mine floor,and takes panjiayao mine field in Datong coal field as the research object.Based on the comprehensive data of mine geology and hydrogeology,the factors of mine water filling are analyzed,and the main controlling factors of floor water inrush during No.5 coal mining are screened and determined.Focusing on the distribution characteristics of faults in the study area,the influence of different fault drop and dip angle on floor water inrush is quantitatively described by using FLAC^3D simulation software.Then,based on the interval variable weight model of incentive and punishment mechanism,the vulnerability of water inrush from coal seam floor is evaluated.The results show that:（1）The main water filling aquifer of panjiayao mine field is Ordovician limestone aquifer,and the water filling channel is fault fracture zone.Water inrush from coal mine is controlled by the characteristics of water filled aquifer,water resisting layer and structure.Among them,water pressure,water richness and permeability coefficient characterize the characteristics of aquifer;Equivalent thickness of the effective waterproof layer and thickness of brittle rock in the effective waterproof layer characterize the characteristics of water resisting layer;The structures are characterized by collapse-column,fault distribution characteristic and fault scale index.（2）Different fault dip angles and fall have different effects on water inrush from coal seam floor.With the decrease of fault dip angle,the influence range of floor water inrush continues to expand,showing a power function relationship L=45.750（πα/180）^-2.536;With the increase of fault drop,the influence range of floor water inrush is also expanding,which also shows a power function relationship L=6.684H^0.710.Based on this,the statistical model of influence range,fault dip and drop is summarized.（3）Based on the interval variable weight vulnerability evaluation model of incentive and punishment mechanism,the risk of water inrush from coal seam floor is divided into five areas:safe area,safer area,transition area,more dangerous area and dangerous area,the area proportion is 23.53%、11.37%、10.20%、16.08%、38.82%.By comparing and analyzing the evaluation results of variable weight and constant weight models,it is found that the overall distribution trend of water inrush risk areas is consistent.However,there are obvious differences at the abrupt changes of local faults,indicating that the variable weight model effectively highlights the control effect of faults on water inrush,and better describes the water inrush situation of regional floor,which is more in line with the reality.