Research On Principal Technology Of Recovering Room Coal Pillar With Combined Artificial Pillar And Solid Backfill Mining

Given the extensive roof caving, mine earthquake, spontaneous combustion in gob area and considerable surface subsidence caused by coal pillar failure, this thesis proposes a new method to extract remained room coal pillar, namely, recovering room coal pillar with artificial pillar on the foundation of research on solid backfill mining technology. In addition, the newly developed technology can not only improve the recovery ratio but also optimize the strata movement behavior. This thesis analyzes the mechanical characteristic of cemented material, the development of overlying strata support system and the principles of strata behaviors in different conditions of size and interval of artificial pillars systematically with method of laboratory test, theoretical analysis and numerical analysis. Finally, it processes the engineering design of recovering room coal pillars on the basis of geological conditions of Changxing colliery. The main achievements are as followed:(1) The thesis introduces the technical principle and recovering processes of the technology of recovering room pillar with artificial pillar. It also proposes the system composition, system layout and key technology of the newly developed method.(2) The thesis analyzes the physical and mechanical property of cemented material in different conditions of cement-tailing ratios, including the conveying property, compression strength and tensile strength. It finally determines the optimal cement-tailing ratio in terms of conveying property and compression strength.(3) On the basis of analyzing surrounding rock deformation, the thesis develops the structural and mechanical model of artificial pillar, backfilling body and surrounding rock. Besides, it analyzes the developing process of support system and deduces the computational formula of roof subsidence and gets the relation curve of size and interval of artificial pillar based on the strength of artificial pillar.(4) The thesis gets the strata behaviors in different conditions of pillar size, pillar interval and backfilling material and determines the optimal pillar size and pillar interval based on the geological conditions of Changxing colliery.