When gob-side entry retaining is implemented in deep coal seams threatened by rockburst, the cementbased supporting body beside roadway will bear greater roof pressure and strong impact load. Then the supporting body ...When gob-side entry retaining is implemented in deep coal seams threatened by rockburst, the cementbased supporting body beside roadway will bear greater roof pressure and strong impact load. Then the supporting body may easily deform and fail because of its low strength in the early stage. This paper established the roadside support mechanical model of gob-side entry retaining. Based on this model,we proposed and used the soft–strong supporting body as roadside support in the gob-side entry retaining. In the early stage of roof movement, the soft–strong supporting body has a better compressibility, which can not only relieve roof pressure and strong impact load, but also reduce the supporting resistance and prevent the supporting body from being crushed. In the later stage, with the increase of the strength of the supporting body, it can better support the overlying roof. The numerical simulation results and industrial test show that the soft–strong supporting body as roadside support can be better applied into the gob-side entry retaining in deep coal seams threatened by rockburst.展开更多
A non-pillar coal-mining technology with an automatically formed entry is proposed,which reduces the waste of coal resources and the underground entry drivage workload.Three key techniques in this technology cooperate...A non-pillar coal-mining technology with an automatically formed entry is proposed,which reduces the waste of coal resources and the underground entry drivage workload.Three key techniques in this technology cooperate to achieve automatic formation and retaining of the gob-side entry,and to realize nonpillar mining.Constant-resistance large deformation(CRLD)support ensures the stability of the entry roof;directional presplitting blasting(DPB)separates the entry roof and the gob roof;and a blockinggangue support system(BGSS)integrates the caved rock material as an effective entry rib.An industrial test was conducted to verify the engineering effects of these key techniques.The field application results showed that the retained entry was under the pressure-relief zone due to the broken-expansion nature of the caved rock mass within the DPB height.After going through a provisional dynamic pressure-bearing zone,the retained entry entered the stability zone.The final stable entry meets the requirements of safety and production.The research results demonstrate the good engineering applicability of this technology.By taking the framework of the technology design principles into consideration and adjusting the measures according to different site conditions,it is expected that the proposed non-pillar coal-mining technology can be popularized on a large scale.展开更多
Roof bolting has been used in underground entry(roadway)support in U.S.coal mines since the Coal Mine Health and Safety Act of 1969(US Congress,1977)recognized roof bolting as the only means of underground entry(roadw...Roof bolting has been used in underground entry(roadway)support in U.S.coal mines since the Coal Mine Health and Safety Act of 1969(US Congress,1977)recognized roof bolting as the only means of underground entry(roadway)support.For U.S.underground coal mines,roof bolting pattern is fixed at 44 ft(1.21.2 m),except in the Pittsburgh Seam where longwall mining is practiced,with occasional 3.64 ft(1.11.2 m)pattern.However,roof falls or roof failure often occurs in roof-bolted entries in U.S.coal mines.Roof falls can roughly be divided into four types:skin falls,large falls,cutter roofs,and massive falls.Based on this situation,the roof is initially strengthened by bolt based on suspension and friction mechanism.By comparing roof bolting patterns in different coal producing countries,bolt density in all other countries is much higher(except South Africa)than that used in the U.S.In spite of its long history of successful application with hundreds of millions of units installed,roof bolting design is still the lack of a commonly accepted method.展开更多
基金supported by the National Basic Research Program of China (No. 2010CB226805)the Taishan Scholar Construction Project of Shandong Province, China+3 种基金the National Natural Science Foundation of China (No. 51344009)the Research Award Fund for Outstanding Young Scientists of Shandong Province (No. BS2012NJ007)the Ground Pressure and Strata Control Innovative Team Fund of SDUST (No. 2010KYTD105)the Natural Science Foundation of Shandong Province (No. ZR2012EEZ002)
文摘When gob-side entry retaining is implemented in deep coal seams threatened by rockburst, the cementbased supporting body beside roadway will bear greater roof pressure and strong impact load. Then the supporting body may easily deform and fail because of its low strength in the early stage. This paper established the roadside support mechanical model of gob-side entry retaining. Based on this model,we proposed and used the soft–strong supporting body as roadside support in the gob-side entry retaining. In the early stage of roof movement, the soft–strong supporting body has a better compressibility, which can not only relieve roof pressure and strong impact load, but also reduce the supporting resistance and prevent the supporting body from being crushed. In the later stage, with the increase of the strength of the supporting body, it can better support the overlying roof. The numerical simulation results and industrial test show that the soft–strong supporting body as roadside support can be better applied into the gob-side entry retaining in deep coal seams threatened by rockburst.
基金This work was supported by the National Key Research and Development Program of China(2016YFC0600900)the Program of China Scholarship Council(201806430070).
文摘A non-pillar coal-mining technology with an automatically formed entry is proposed,which reduces the waste of coal resources and the underground entry drivage workload.Three key techniques in this technology cooperate to achieve automatic formation and retaining of the gob-side entry,and to realize nonpillar mining.Constant-resistance large deformation(CRLD)support ensures the stability of the entry roof;directional presplitting blasting(DPB)separates the entry roof and the gob roof;and a blockinggangue support system(BGSS)integrates the caved rock material as an effective entry rib.An industrial test was conducted to verify the engineering effects of these key techniques.The field application results showed that the retained entry was under the pressure-relief zone due to the broken-expansion nature of the caved rock mass within the DPB height.After going through a provisional dynamic pressure-bearing zone,the retained entry entered the stability zone.The final stable entry meets the requirements of safety and production.The research results demonstrate the good engineering applicability of this technology.By taking the framework of the technology design principles into consideration and adjusting the measures according to different site conditions,it is expected that the proposed non-pillar coal-mining technology can be popularized on a large scale.
文摘Roof bolting has been used in underground entry(roadway)support in U.S.coal mines since the Coal Mine Health and Safety Act of 1969(US Congress,1977)recognized roof bolting as the only means of underground entry(roadway)support.For U.S.underground coal mines,roof bolting pattern is fixed at 44 ft(1.21.2 m),except in the Pittsburgh Seam where longwall mining is practiced,with occasional 3.64 ft(1.11.2 m)pattern.However,roof falls or roof failure often occurs in roof-bolted entries in U.S.coal mines.Roof falls can roughly be divided into four types:skin falls,large falls,cutter roofs,and massive falls.Based on this situation,the roof is initially strengthened by bolt based on suspension and friction mechanism.By comparing roof bolting patterns in different coal producing countries,bolt density in all other countries is much higher(except South Africa)than that used in the U.S.In spite of its long history of successful application with hundreds of millions of units installed,roof bolting design is still the lack of a commonly accepted method.
