Experimental Research On Goaf Filling With Skeleton Type Backfill Paste

The total quantity of the pressed coal under the buildings,water body and the railways has reached 13.79 billion ton in our state-owned key coal mines, while the pressed coal under the villages account for 60% of the total quantity. In order to not damage the building on the surface while exploiting the coal under the villages, the author put forward the imagine of goaf filling with skeleton type backfill paste and did research according to the geological condition of Guantai coal mine in Fengfeng mining area. The author mainly did the research as follows:(1)The author consulted a lot of documents introducing the mining subsidence manifestation briefly, and summarized the classic mining subsidence prediction theory systematically. Extremum calculation of the ground deformation is an important content of the surface subsidence prediction, and parameters which are showing the construction damage levels, such as the tilt,curvature and horizontal deformation etc, are decided by the maximum lowering value.(2) And the author had made the paste into ordinary backfill test block by a certain material ratio to test the intensity of the different ages test block; then chose different forms of skeleton, and made the paste and the frame into backfill test block for testing the intensity of the test blocks in the different ages to select the reasonable frame form according to the test results.The test results showed that skeleton type backfill both in the early strength and the capacity of resistance to deformation is better than ordinary backfill.(3) Comparing with caving method, it is no doubt that paste backfill will significantly lower the maximum subsidence of surface. In order to compare the effectiveness of reducing subsidence of ordinary paste filling with skeleton type backfill, plane stress model was chosen to conduct similar material simulation test. The results showed that the effectiveness of reducing subsidence of the skeleton type paste backfill is better than ordinary paste backfill.(4)In order to get the value of the surface deformation of the caving method,the ordinary paste backfill and the skeleton type paste backfill in processing the goaf, the author employed FLAC 3D established numerical model and operated with it. The operation results showed that the surface deformation caused by the caving method will cause serious damage to the buildings. The operation results also showed that if the goaf was backfilled with ordinary paste, it will cause slight damage to the buildings, beyond that the goaf backfilled with skeleton type paste will cause no damage to the buildings.(5) After analyzing the feasibility of skeleton type paste filling goaf from the technically feasible, the economic rationality and the social benefit, the conclusion is that the technology of skeleton type paste filling goaf can realize completely at the basic of the foundation of current paste filling technology.