Numerical Simulation Study On The Damage Of Inclined Coal Floor With Fault Structure And The Law Of Water Inrush Under The Influence Of Different Factors

Coal resources occupy an important position in the energy field of our country,and play a positive role in promoting the economic development of our country.The safe production of coal mines is a link that can not be ignored in the process of national economic development.However,the problem of mine water disaster has been affecting the safe mining of coal resources,and poses a major threat to the economic benefits of coal mining enterprises and the life safety of underground workers.Through the analysis of previous mine water inrush accidents,it is found that the working face with fault structure is most prone to water inrush,and the existence of fault structure makes it easier for confined water to be introduced into the stope.Previous researchers have done a lot of work on the mechanism of mine fault water inrush and achieved good research results,but these research results are mainly aimed at horizontal and near-horizontal coal seams.However,there is little research on fault water inrush in inclined face with fault structure.Therefore,in this paper,through the combination of theoretical analysis,numerical simulation and water-bearing transient electromagnetic detection of the floor of inclined working face,starting with the main control factors affecting the floor failure depth of coal seam inclined working face under the joint action of mine pressure and confined water,the law of fault water inrush under the condition of mining with pressure in deep inclined working face is studied,and the following results are obtained.(1)Based on the previous research results,the fault water inrush mechanism of inclined coal seam with fault structure is theoretically analyzed.The main controlling factors affecting the failure depth of coal seam floor are obtained,such as coal seam dip angle,coal seam buried depth,aquifer water pressure and so on,and the main controlling factors affecting fault activation are fault dip angle,fault drop,width of broken zone and coal seam mining depth.and the influence of fault dip angle and coal seam mining depth on fault activation is more obvious.From the point of view of mine pressure,the conditions for the occurrence of fault water inrush are obtained,that is,the failure depth of the floor caused by mining in the working face can not be less than the depth of the intersection between the peak stress line of the floor and the fault.The confined water has the function of guiding and scouring and expanding the diameter of the coal seam floor.Under the influence of the coal seam mining disturbance,the stress field of the floor strata and the dynamic equilibrium system before the seepage field are destroyed,and the stress field changes accordingly.The seepage field and stress field need to experience many times of coupling before they can reach the dynamic equilibrium again.(2)Three influencing factors of coal seam floor failure depth,coal seam dip angle and confined water pressure are selected from the factors affecting coal seam floor failure depth obtained from theoretical analysis.Taking the 21310 fault-bearing structural face of a coal mine in Ningyang,Shandong Province as the geological background,the model is established by FLAC3D software,and the influence law of floor failure depth and fault water inrush under different coal seam burial depth,different coal seam dip angle and different water pressure are studied by numerical simulation.It is found that under the condition of different coal seam dip angle,when the coal seam inclination angle is 30°,the failure depth of the coal seam floor is the largest and the plastic zone of the floor leads to the fault first;under the condition of different mining depth,the failure depth of the coal seam floor increases with the increase of the mining depth,and the deeper the mining depth is the more likely the floor fault water inrush is;the greater the confined water pressure is,the deeper the floor failure depth is,the more prone to fault water inrush accident.(3)Based on the detection results of transient electromagnetic method on the floor of 21310 inclined face,combined with the results of theoretical analysis and numerical simulation,two kinds of water disaster prevention and control schemes of fault coal pillar and hydrophobic depressurization are established for 21310 inclined face with fault structure.Through the prevention and control effects of the two schemes,It can be seen that reasonable coal pillar width and reducing confined water pressure can effectively ensure the safe mining of the working face.