In order to solve the surrounding rock control problem of large section gangue replacement roadway under complicated conditions, this paper analyzed the impact to the roadway controlling produced by the geological con...In order to solve the surrounding rock control problem of large section gangue replacement roadway under complicated conditions, this paper analyzed the impact to the roadway controlling produced by the geological conditions such as high ground stress, folded structure tilted roof asymmetry and soft wall rock, and built the tilt layered roof structural mechanics model to clarify the increase span mechanism of the weak coal instability. Then, we proposed the combined control system including roof inclined truss cable, coal-side cable-channel steel and intensive bolt support. And then by building the structural mechanics model of roof inclined truss cable system, the support principle was described. Besides, according to this model, we deduced the calculation formula of cable anchoring force and its tensile stress. Finally surrounding rock control technology of large section roadway in fold coal pillar area was formed. Field practice shows that the greatest roof convergence of gangue replacement roadway is 158 mm and coal-side deformation is 243 mm. Roadway deformation is controlled effectively and technical support is provided for replacement mining.展开更多
Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing production.B...Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing production.But the caving ratio is low,which might result in some disasters,such as roof falls,induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body,the tall,broken section of the top coal（a granular medium）of an extremely steep seam（over 60°）shows clear characteristics of nonlinear movement.We have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed zone.Based on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas,we conclude that the weakened top coal can be regarded as a non-continuous medium.We used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal mine.The results of our simulation, experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving,relieve space for large area dynamic collapse of top coal,prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining.展开更多
文摘In order to solve the surrounding rock control problem of large section gangue replacement roadway under complicated conditions, this paper analyzed the impact to the roadway controlling produced by the geological conditions such as high ground stress, folded structure tilted roof asymmetry and soft wall rock, and built the tilt layered roof structural mechanics model to clarify the increase span mechanism of the weak coal instability. Then, we proposed the combined control system including roof inclined truss cable, coal-side cable-channel steel and intensive bolt support. And then by building the structural mechanics model of roof inclined truss cable system, the support principle was described. Besides, according to this model, we deduced the calculation formula of cable anchoring force and its tensile stress. Finally surrounding rock control technology of large section roadway in fold coal pillar area was formed. Field practice shows that the greatest roof convergence of gangue replacement roadway is 158 mm and coal-side deformation is 243 mm. Roadway deformation is controlled effectively and technical support is provided for replacement mining.
基金Financial support for this work,provided by the National Natural Science Foundation of China(No.11002021)the Doctoral Subject Foundation of the Ministry of Education of China(No.20070008012)the National High Technology Research and Development Program(No.2008AA062104)
文摘Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing production.But the caving ratio is low,which might result in some disasters,such as roof falls,induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body,the tall,broken section of the top coal（a granular medium）of an extremely steep seam（over 60°）shows clear characteristics of nonlinear movement.We have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed zone.Based on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas,we conclude that the weakened top coal can be regarded as a non-continuous medium.We used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal mine.The results of our simulation, experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving,relieve space for large area dynamic collapse of top coal,prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining.
