Research On Influencing Factors Controrling Surface Subsidence With Paste Backfilling Mining Method

The immediate cause of the damage of ecological environment and surface buildings is mining subsidence and releasing of mining solid waste. The basic method which can relieve the damage of ecological environment and buildings is effetely controlling and relieve surface subsidence, reasonably disposing and utilize mining solid waste. For all of above, this paper use theory of backfilling mechanics, fluid mechanics, mining subsidence and numerical simulation method to discuss the law of surface subsidence with coal gangue paste backfilling mining method.First, the paste backfilling, the basic characters of paste backfilling are analyzed. And the fluidity features, rheologic features and the pumpability of paste slurry are analyzed. The general backfilling materials are introduced and the influencing factors on the coal gangue paste backfilling body strength and the pumpability of paste slurry are analyzed. The action mechanics and distortion destroy feature of paste backfilling body are analyzed. It is demonstrated by trial that paste backfilling body has high residual compression strength with load-carrying ability but little tensile strength; the paste backfilling body show obvious plastic strengthening feature under condition of trial compression even low confining pressure condition. Therefore, this feature can be used to properly low the requirement of backfilling body's strength and the cost of backfilling material and obtain better economic benefits in the process of mining design of paste backfilling without village moving.The roof just fractures without caving for backfilling mining. Therefore, the backfilling body must have early strength. It requires that backfilling body could keep its early stability and have supporting capability in some degree to immediate roof. There are three influencing factors which influence the surface subsidence for backfilling mining method. It is the subsidence of roof before backfilling, non-backfilling account and the decrement of backfilling body. The influencing laws which influence the surface subsidence with paste backfilling mining method are study by means of the numerical simulation soft UDEC. The relationship curve of the strength of backfilling body versus the max surface subsidence and the backfilling rate versus the max surface subsidence are obtained. The abutment pressure distribution in front of work face and the subsidence of roof after work face with backfilling method are simulated. It is demonstrated that the influencing range of abutment pressure and the stress concentration factor decreases with the strength of backfilling body increase. And the movement of the roof can be better controlled by backfilling mining. The high the strength of backfilling body, the effect to control the roof is better.