Study On Very Close To "Three Soft" Thick Coal Seam Layering Mining Under Continuous Pressure Of Fully Mechanized Working Face

In order to more thoroughly understand very close to extracting seam working face appeared mine pressure law, this article thank a mine of huainan mining group5111B11b working face as the research object, the experimental study and similar simulation, numerical simulation and field measurement method, system research is extremely close to "three soft" thick coal seam layering mining overburden stratum at the fully mechanized working face under the continuous "three zones" height and the destruction of the stress field, displacement field and plastic zone distribution characteristics, analyzes the dynamic evolution characteristics of overburden rock fracture, summarized the extremely close to extracting seam under the condition of stope firstly, for this kind of working face management and control of surrounding rock, roof support selection techniques provide better guidance. The main results of this paper are as follows:(1) Through the theoretical analysis, the criterion of extremely close distance coal seam to clamp into extremely close distance coal seam roof is divided into and chipped stone false roof and broken rooftop3class; Also calculate the5111B11b upper coal seam working face of immediate roof and roof first caving step interval distance, basic roof periodic and reasonable support resistance, to provide a theoretical guidance in the selection of hydraulic support.(2) Through the analog simulation to determine the upper coal seam mining "three belts" growth altitude, the lower coal seam mining does not have obvious cyclical phenomenon, the peak stress of top, bottom, caving Angle and strata caving form is different.(3) By use of FLAC3D numerical simulation software to simulate mining working face, respectively get along direction of working face, stress field, displacement field and plastic zone and the three-dimensional distribution of vertical stress, at the end of the upper coal seam mining, the overall shape of the plastic zone are two high middle and low "saddle" form, in after the lower coal seam mining, the overall shape of the plastic zone is no longer present in the middle high "saddle" form on both ends of the low, but high middle low on both ends of the parabolic shape.(4) Based on statistical processing of working resistance of hydraulic support at the beginning of the cycle of respectively get support working resistance and resistance levels, at the end of the supporting force and the stent adaptability evaluation, put forward supporting force is low at the beginning of the cause and the solution. During mining, before and after the hydraulic support column force not average, should strengthen the management of hydraulic support.(5) Roadway deformation observation statistics, this paper analyzes the working face mining on the influence degree of the two lane, it is concluded that no mining influence area, mining area and intense mining influence area, to face during the period of stoping forepole provides the reference.In this paper, the application of research results, has realized the extremely close "three soft" thick coal seam layering mining of mining safety and efficiency, to the sustainable development of local coal industry in China has important practical significance and great economic benefits.