Study On Super-high-water Material Backfilling Technology With Extremely Thick Igneous Rock Above Coal Seam In Anju Mine

An extremely thick igneous rock,which exists in overburden rocks,has both favorable and potential safety threats for coal mining.The extremely thick igneous rocks are characterized by large rigidity,high strength,and large thickness.Their subsidence deflection is very small,and they can play a good load-bearing role for the overburden rocks.However,as the mining continues,the igneous rocks and the lower rock formations are separated.As the distance between the layers increases,the elastic energy accumulated in the igneous rock is also increasing.When it exceeds the limit breaking fault throw,it is likely to pose a major threat to the safe mining of the working face,and may cause uneven surface subsidence.Backfill mining technology has good results in controlling overburden activities and surface subsidence.However,this technique has rarely been practiced in the control of extremely thick igneous rock activities.Based on this,taking into consideration the target mine which mining under villages,railways and water bodies,the author put forward the Study on Super-high-water Material Backfilling Technology with Extremely Thick Igneous Rock above Coal Seam in Anju Mine.In this paper,the author studies the structural stability of extremely thick igneous rocks through theoretical analysis,introduces the technology of filling and mining of ultra-high water materials,and studies on the optimization of the technical parameters of super-high-water material backfilling mining under this condition by Flac^3D numerical simulation.According to the research results,this paper gives the prediction of surface movement deformation by MSPS,a software to mine subsidence forecast,and designs the super-high-water material backfilling mining systems.The main research process and results are as follows:?1?The extremely thick igneous rock under actual conditions is simplified into a two-end fixed-supported beam model.Through the theory of elastic mechanics,the stress distribution under the action of uniform load and igneous rock weight is established respectively and the expression of the internal stress distribution of the extremely thick igneous rock is analyzed.Based on the consideration of limit thinking,the location where the igneous rock is most likely to break first is analyzed,that is x?28?±l and x?28?0,y?28?h/2.Computation and comparison of the boundary conditions shows that the two ends of the igneous rock first fracture,and from this,the ultimate breaking fault throw expression of the huge thick igneous rock is deduced.?2?Through Flac^3D,an optimized simulation study on the technical parameters of super-high-water material backfilling mining under the extremely thick igneous rock was conducted.The results show that super-high-water material backfilling mining under the extremely thick igneous rock has remarkable effect on the control of roof and overlying strata subsidence.With the increasing of the water volume fraction of the material,the overburden subsidence volume shows an increasing trend.Under the condition of 85%filling rate,mining has a significant control effect on the roof when super-high-water material backfilling with a water volume ratio of not more than 95.5%.With the reduction of the water volume ratio,the lateral support pressure of the coal pillar can be appropriately reduced,and the distribution range of workface stress concentration can be weakened and the further deformation of the surrounding rock can be suppressed.?3?According to the predicted results of surface movement and deformation,the use of super-high-water material backfilling mining can minimize the destruction of surface buildings and save compensation costs.Then,the super-high water material backfilling mining system under the extremely thick igneous rock was designed,including standard sizes of filling packs,the ability design of the filling pumping stations and its site selection,the design of filling pipelines and its diameters,and the design of filling support.Practice proved that,the design of the filling system has certain reliability and feasibility,and it can realize the application of the super-high-water material backfilling mining technology under the conditions of depositing extremely thick igneous rocks above coal seams.