Research And Application Of Support Technology For Large Deformation And Fractured Mining Roadway In Xin'an Coal Mine

Coal resource is the basic energy in our country.The annual coal mining volume is about 3.5 billion tons,and the length of mining roadway is about 13,000 kilometers.Up to 80%of coal mine accidents occur in mining roadway.Maintaining the safety of mining roadway is the most important task of coal mine safety.At the level of-380m in Xin'an Coal Mine,the surrounding rock of the mining roadway is loose and fragmented,the integrity is poor,the supporting parameters are unreasonable,the roof sinks seriously,the displacement of the two sides is large,the repairing rate of the roadway is high,the amount of engineering is large and the cost is high,which seriously affects the normal excavation and safe production of the roadway.Therefore,it is of great significance to study the support technology of large deformation and fragmentation mining roadway in Xin'an Coal Mine.The main contents and conclusions of this paper are as follows:(1)The engineering geological survey of 2301 working face of Xin'an Coal Mine was carried out.The typical rock of roadway,coal,medium sandstone and siltstone,were selected to carry out mechanical tests under natural and saturated conditions.The results show that the uniaxial compressive strength and modulus of elasticity of rock samples decrease under saturated condition,the change rate of uniaxial compressive strength of coal No.3 is the largest,and that of elastic modulus of medium sandstone is the largest.With the increase of confining pressure,the ultimate compressive strength and residual strength of rock samples increase.By simulating the temperature and relative humidity of the underground,three rock samples were cured and uniaxial compression tests were carried out.The results show that the water content of three rocks increases with time,and the water content of coal increases the fastest.With the increase of curing time,the peak strength decreases gradually,and a turning point appears.After the turning point,the peak strength decreases rapidly,and weathering effect on the three rocks is obvious.(2)According to the idea of coupling support and the choice of support form of roadway,the scheme of active-passive coupling support with bolt-mesh-cable-shotcrete and I-beam is determined.FLAC is used to simulate the parameters of bolt and cable support in mining roadway,and the variation law of stress and displacement in surrounding rock of roadway is analyzed.The parameters of roadway support are obtained as follows:The specification 22*2300mm threaded steel resin bolt is adopted,the row spacing between top bolts is 750*1600mm,the row spacing between top bolts is 850*1600mm,the row spacing between top bolts is₁7.8*8000mm,the row spacing is 1500*1600mm,the row spacing is 17.8*4500mm,and the row spacing is 850*1600mm;the head of I-shaped steel shed is 3500mm,the shed leg is 280mm,and the shed spacing is 1600mm,which is located in the middle of the bolt and anchor cable.(3)The active-passive coupling support technology is applied to the trench along 2301 working face.Three monitoring sections are selected to monitor the displacement values of the two sides of the roadway and the roof and floor.The displacement values of the two sides of the three stations are larger than the displacement values of the roof and floor.After the excavation of the roadway is completed,the time for the surrounding rock of the roadway to stabilize is about 14 days.According to the convergence criterion of roadway stability,the convergence deformation of roadway surrounding rock is within the allowable convergence range,and the roadway is judged to be in a stable state.