Study On The Law Of Strata Behaviors In Room And Pillar Residual Coal Repeated Mining

Room and pillar mining method was one of the main mining methods in our country in the 1970s and 1980 s. This method was widely used in many coal mines in our country for its simple operation, mining effect is good, high security. However, this mining method has serious drawbacks that low coal recovery rate and utilization of coal resources. For the room and pillar mining method was used and promoted in large area, most of the residual coal resources have not been produced in the coal seam. Our government plan to promote the sustainable development of coal resources and improve the utilization of coal resources in the 12th five-year plan in our country. It can create the huge economic value and make good and rational use of the residual coal by repeated mining this part of coal resources. It is important to determine the room and pillar residual law of mine pressure behavior in the process of repeated coal mining. And it is the premise to repeated mining smoothly. This article is in view of the law of mine pressure of room and pillar appear in the process of the residual coal mining. It great influence on residual coal repeated mining.In view of the room and pillar mining residual coal resources, in this paper, the mechanical of coal pillar and roof and floor characteristics were analyzed. Roof and floor about coal pillar under the triaxial stress effect. The roof and floor in abandoned roadway under triaxial stress or horizontal pressure. The edge of coal pillar’s gap and fissure development in an all-round way for the effect of stress concentration and this part of pillars under uniaxial pressure. Due to the pressure of surrounding coal and roof and floor, center position in the coal pillar of extrusion under triaxial pressure. Between the edge of coal pillar and the center is part of the coal belongs to the transition state. Coal pillar was divided into loose edge area, transition area and coal pillar elastic-plastic central area according to the different pressure.On the basis of force analysis, this paper established a finite element model of the residual coal mining. On the basis of the residual coal occurrence conditions of Shanxi MeiYun Mining Group XiHe coal mine, Using FORTRAN finite element program for the whole mining process in numerical simulation, the simulation results show that:The stress of roof and floor and displacement distribution on the coal pillar in the mining process was significant effect by face length, coal pillar size, face towards, coal production area ratio and the geological conditions of roof and floor, In this paper, from the above several aspects, mining pressure was analyzed combined with the results of numerical simulation.On the basis of numerical simulation, similarity simulation test for repeated mine the residual coal was conducted under XiHe coal conditional using 3d analog simulation test bench designed by the MTI_TYUT. By similarity simulation experiment study, we have found that: It was that working face across the abandoned roadway has a great influence on the coal pillar and the roof stress distribution. Working face across the abandoned roadway make the stress of the roof in front of working face redistribution and the pillar stress state change. Through the method that combining the experiment phenomenon and the experimental data, this paper expounds the changing rule of the stress and displacement on the roof influenced by the mining area to open eyes, face under the condition of different air zenith distance across the alley, immediate roof and main roof fall across; the sign of the main roof first and periodic pressure phenomenon; the influence factors of main roof falls distance and the changing rule of coal pillar in three areas in the coal pillar stress state changes.