Layered Flexible Reinforcement Technology For Long Distance Borehole Of Coal Wall In Large Mining Height Face

Along with the increase of coal seam depth and mining height working face in China,the coal wall and roof caving of working face have become the technical problems to be solved urgently in comprehensive mining technology of large mining height.Therefore,based on field investigation and relevant literature both at home and abroad on the basis of extensive research,in addition,16001 large mining height are broken as the engineering background of fully mechanized working face,By using the methods of theoretical analysis,laboratory test,numerical simulation,similar test and field measurement,some work has been done on prevention and control of large mining height coal wall face in thick seam.The main research results are as follows:?1?In order to realize the large mining height efficient safety mining,based on the large mining height are broken rest work another help mechanism,main influencing factors and traditional prevention and control of coal wall piece help measures were analyzed,and the results show that the rest work another help position is in the upper,the traditional strengthening methods is by support pressure in coal wall cracks or help later passive measures,there is the poor help effect,take mining face time and supporting intensity is low and the high input problem.Therefore,the long distance advance grouting layer flexible reinforcement technology is proposed.?2?The mechanical properties of the aluminum-plastic composite pipe and the specimen containing"grouting+flexible pipe"were obtained through laboratory tests.The research shows that the aluminum plastic composite pipe with a diameter of 20 mm is selected as the grouting pipe,and its tensile strength is 22.01 MPa and compressive strength is 8.17 MPa.The number of flexible tubes?1,2 and 3?with"grouting+flexible tubes"increased by 7.33%,14.67%and 24.01%,respectively.The compressive strength increased by 14.10%,17.39%and 21.93%,respectively.The tensile strength increased by 13.62%,22.96%and 24.90%,respectively.?3?With different reinforcement conditions by using the software FLAC³DD large mining height,to simulate the displacement change analysis of the horizontal displacement change rule,it is concluded that the optimal distance between grouting hole.Using UDEC^2D discrete element software for simulating different supporting height,and observe the different position of grouting reinforcement effect on coal seam working face.The results show that the best reinforcement is achieved when the grouting hole spacing is 1.5m and the distance from the roof is 1.5m and 3m.?4?Through analog simulation test on the working face is analyzed,the process under different working condition of reinforced during the process of working face advancing,The grouting hole spacing is 1.5m and the distance between the grouting hole and the roof is 1.5m and 3m.The working face pressure increases by 60.5%compared with that without reinforcement.The reinforcement effect of the slab is good,and the slab of the working face appears lag phenomenon.In the field practice,through optimizing the spacing of grouting holes and the grouting amount,it is found that the flexible reinforcement of coal seam will not cause sudden collapse when the working face is pushed forward,the opening probability is improved,and the daily output is obviously increased,which can provide reference for similar projects in the future.