Study On Fast Excavation Technology Of Anchor Net Support In ’Three Soft’ Extra Thick Coal Seam In Jiaojiazhai

In the process of ’ three soft ’ roadway excavation,there are a series of problems such as low strength of roadway surrounding rock,poor stability of roof,common leakage phenomenon and difficult roadway support.Based on the research background of 5132 transportation roadway in Jiaojiazhai Coal Mine,this thesis systematically studies the rapid excavation technology of anchor net support in ’ three soft ’ extra-thick coal seam through field investigation,theoretical analysis,experimental research,data statistics,industrial test and field test.(1)Through the coal(rock)samples collected on site,the rock physical and mechanical tests are carried out,and the deformation index and strength index of surrounding rock are obtained.According to the analysis,the roof and floor surrounding rock of 5132 transport roadway has low peak strength and poor resistance to deformation,which is a typical three-soft roadway.(2)Through the coal seam anchorage performance test and the surrounding rock loose circle test,the anchorability of the surrounding rock of 5132 transportation roadway was mastered,and the range of surrounding rock loose circle was calculated.In order to enhance the stability of the support system,a coupling control technology of roof long and short anchor cable is proposed.The numerical simulation of the support scheme is carried out by FLAC3 D.The results show that the plastic zone of surrounding rock supported by short anchor cable is 42.4 % less than that of bolt support,and the roof subsidence is also reduced by 20 %.(3)By analyzing the main factors affecting the driving speed of 5132 transport roadway,the ’ keel ’ pre-support structure of roof advanced dense long steel pipe is constructed.The hierarchical control technology system of roof long and short anchor cable is proposed.The slope partial coal cutting method of cantilever roadheader is proposed.The results show that the average monthly footage is increased from 70 m to143 m,the average tunneling rate is increased by 104 %,and the maximum tunneling speed can reach 180 m / month.(4)Field industrial test was carried out on the optimized support scheme,and the mine pressure monitoring of the roadway was carried out by using the monitoring equipment.The results show that the roof separation amount during the excavation of5132 transport roadway is small,the separation range is 0 ～ 35 mm,the maximum displacement of roof and floor is 156 mm,and the maximum displacement of two sides is 82 mm,all within the allowable deformation range,indicating that the optimized roadway support design scheme has good anchoring effect.