Macro-micro Mechanical Behaviors Of Subsidence Disposal Paste And Compatible Deformation Control

Serious environment damage caused by mine surface subsidence and solid waste is a major disaster that the metal mine is facing in China, which has become a major public nuisance. The large-scale successful application of tailings paste surface storage technology and filling technology brings hope for the disposal of surface subsidence area. Solid waste could be processed into paste, and delivered to backfill the subsidence area, which can achieve integrated management of two public nuisances:solid waste and surface subsidence area. This study was developed under the context of paste disposal projects in the surface active subsidence area at Tongkeng Mine, with research contents primarily as follows:(1) The formation of surface subsidence area at Tongkeng Mine and related disaster-causing factors were analyzed. A chained disaster mitigation model for the surface subsidence at Tongkeng Mine was established to obtain the strength and penetration-disintegration features of the disposal body, and the compatible deformation feature of the disposed paste after refilling was a key issue to be addressed for the paste disposal in the subsidence area.(2) Experiments were conducted to investigate the structural features of disposal particle groups which were composed of artificial compound granular media with wide size. The fine particle effect of the disposal body was discovered, the characteristic parameters of disposal body and the variation patterns of waste rocks contents were verified, and the content range of waste rocks in the disposal body was determined; on the basis of the improved small experimental device of direct shear, experiments on the factors influencing mobility and shear strength of disposal body were successfully carried out to verify the patterns of the effect of disposal body’s material characteristics on cohesion c. internal friction angle φ, and stress-strain relationship, revealing the adhesive friction strength mechanism of the disposal body.(3) CT dynamic real-time loading test was performed on the disposal body in the subsidence area to obtain real-time data during the dynamic rupture process of disposal body under various contents of waste rocks and amounts of added cement. A multi-component three-dimensional model of the disposal body was reconstructed. A micro-structural evolutionary pattern of bearing rupture of the disposal body was proposed. The CT value varying pattern during the rupture process of disposal body was verified under different ratios and the CT-value-based calculation formula for the damage of the disposal body was developed, thereby revealing the macro-micromechanical inherent correlation of the disposal body.(4) The permeability tester and quantitative disintegration testing device were made, taking the lead in testing the factors influencing the strength and penetration-disintegration features of the disposal body. As a result, the contents and particle size of waste rocks, characteristic parameters of disposal body, and the pattern of the impact of fine particle contents on permeability coefficient were verified, the quantitative formula of permeability coefficient of disposal body was established by taking the fine particle effect into account, and the pattern of influences of waste rocks contents and added cement amounts on the disintegration features of the disposal body were explored. On the basis of SEM image analysis, the penetration and disintegration mechanisms of disposal body were revealed.(5) The measures for the compatible deformation and its stability control of the disposal body in subsidence area were proposed, taking the lead in applying the critical layer and arch theories into the paste disposal in subsidence area, the physical model of cemented-non-cemented disposal body was established, and the minimum arch height and thickness of the disposal body after refilling were calculated:a refilling subsidence model which took critical layer of cemented disposal body into account was introduced, and the disposals of the subsidence area in different conditions were simulated with the PFC2D. The first proposed separation factor was used to analyze the disposal result of the subsidence area and determine the optimal disposal processing parameters.(6) The findings were applied in the disposal of the surface active subsidence area at Tongkeng Mine, and according to the basic disposal principle of "horizontally sectioning and vertically layering" the subsidence area, the preparation and refilling processes of the disposal body were designed.