Study On The Movement Of Upper Strata And The Pressure Behavior Law Of Close Distance Coal Seams

In this paper the engineering background of close distance coal seam group YangYi coal mines. With the aid of theoretical analysis,laboratory analog simulation test and computer numerical simulation test method,etc. Analytic hierarchy process(ahp) combined with multiple objective factors,for a particular expounded what is close coal seam coal rock conditions,The definition of close coal seam has carried on the quantitative analysis. On the basis of the comparative demonstration analysis of close distance coal seam group of combined mining with single coal bed mining strata structure of the difference of migration change and close distance coal seam structure stress field and displacement field of a combined mining strata distribution, firstly summarizes the close joint open mining of coal seam pressure, for YangYi coal mine and similar mine safety mining geological conditions to provide certain theoretical guidance. Paper main results are as follows:(1) According to construct the "medium- block" roof structure model, the mechanism and dynamic analysis of the broken roof caving process. From rock characteristics, strength and integrity, mining effect of coal seam and roof surrounding rock stress and stability coefficient of impact on roof stability analysis, using the multi-objective analytic hierarchy process(ahp) to quantitative evaluation of various factors index, according to the occurrence conditions and mining conditions of coal seam and interlayer mining influence factors such as the concept of close distance coal seam in preliminary, many coal seam occurrence condition can be divided into the close and close coal seam of coal seam and the extremely close distance coal seams.(2) Through laboratory analog simulation experiment, close in the process of the combined mining of coal seam, contrast different fault distance and a mining evolution characteristics of stress field and displacement field of a coal seam working face up and down along the direction of the reasonable to determine the final offset to 40 cm, corresponding geometric similarity than actual fault distance of 20 m.(3) Summary analysis close movement combined mining of coal seam and breaking law, after the big green surface mining roof block fracture structure, from the shelves in the process of surface mining on secondary damage has been breaking rock strata, the secondary fracture position is located in the massive rock core position. The shelves first face roof pressure interval for half of the single coal seam mining. With thick coal seam layering mining caving in the overlying strata structure similar to the combined mining.(4) Using discrete element numerical simulation software simulation YangYi UEDE close combined mining of coal seam in coal mine, respectively get close distance coal seam group of combined mining face up and down the stress field and displacement field migration evolution law of close distance coal seam combined mining abutment pressure differs from that of single coal seam mining, mining goaf behind the abutment pressure changes in the waste rock stress reduced area- caving compaction area to stress lowers area. At the same time, according to the simulation results shows reasonable combined mining face up and down the offset range of 20 ~ 30 m.(5)For Yang Yi of Daqing coal mine and mining under the surface near distance coal seam joint mining engineering geological conditions, through the observation analysis of roadway ahead of the monomer hydraulic pillar pressure changes, obtains the best rational staggered distance, and for mining under the similar conditions to the exemplary role, and hence have broad application prospects.