Study On The Mechanism Of Activated Water Inrush From Fault Floor In Deep Seam With Pressure Mining

Fault water inrush in coal mines has long puzzled coal mine safety production.There are many factors affecting the activated water inrush process of the floor fault.In order to solve the problem of activated water inrush from the floor fault,the geological structure,the original rock stress,the water pressure of the aquifer and the mining mode should be taken into consideration,and the systematic study on the activated water inrush from the floor fault is carried out.In this paper,the mechanical analysis,numerical solution,FLAC numerical simulation and engineering practice are combined to study the fault activation and the mechanism of the water inrush in the bottom of the stope.The main research results are as follows:(1)Based on the theory of semi infinite body,the mechanical model of fault activation mechanism of coal seam floor is established,and the formula of any point shear stress on the fault under the action of ore pressure is derived.The geological parameters of the working face are put into the shear stress calculation formula,and the shear stress of the fault is drawn with the change curve of the working face.It can be intuitively shown that any factor changes the shear stress on the broken plane.(2)The influence of fault drop,fault dip and aquifer water pressure on activation water inrush from mining fault on confined aquifer is obtained by FLAC3D numerical model software..(3)According to the actual geological conditions of Yangcheng coal mine 1311 working face,the FLAC numerical calculation model is set up.Through the analysis of the vertical stress,shear stress,plastic zone and pore water pressure in the process of working face,it is determined that the water inrush accident is easy to occur in the working face.The maximum damage depth of the 1311 working face is 33.77 m,which is close to that obtained by numerical simulation..(4)The actual geological parameters of the 1311 working face are put into the fault activation process.The maximum damage depth on the fault is 31.84 m,which is close to the measured value of 33.77 m and the 34.84 m obtained by the numerical simulation.In order to reduce the risk of water inrush in 1311 working face,according to the actual situation of mining face and the previous study,the measures of setting up waterproof pillar are put forward,and the size of waterproof coal pillar is 26 m by calculating and setting the 1311 working face.