Study On Surrounding Rock Stability Of The Fully Mechanized Face With Greater Mining Height For The Thick Coal Seam

The technology of fully mechanized mining with large mining height is one of the important development directions of the thick coal seam mining technology. Because of the special nature of the failure law of surrounding rock with large mining height fully-mechanized mining, it leads to a series of surrounding rock instability phenomenon. Therefore, surrounding rock stability and its control technology has become an important topic in coal mining height fully mechanized mining. This paper takes Lu’an Group Wang Zhuang coal mine7105full-mechanized mining face with large mining height for the practical engineering background, from the roof caving regularity, support strength, surrounding rock stability of coal wall and other aspects, using field data collection, theoretical analysis, numerical simulation method, has a intensive study on the surrounding rock stability and its control technology with large mining height fully-mechanized working face for thick coal seam.Firstly, through the combined method of theoretical analysis and numerical simulation, pressure behavior of large mining height fully-mechanized working face is studied systematically, it is determined of roof caving regularity and hydraulic support reasonable support strength, providing a theoretical basis for the working face with large mining height and support selection.Secondly, using the limit equilibrium theory, combined with Lade-Duncan strength criterion under plane strain condition, considering the intermediate principal stress, the coal wall width of plastic zone and stress distribution has been studied, and has discovered that the strength of coal body, side protecting plate resistance, mining height and depth of coal seam are the important factors affecting the coal wall. By numerical simulation, coal wall stress characteristics with large mining height fully-mechanized working face are analyzed. With the increase of mining height, plastic damage area of the working face in front of the coal wall, abutment pressure, horizontal displacement of coal wall have increased. And the coal wall central is the most serious destruction area, the coal wall stability is the worst, it shall be treated as the key protection area. By building the mechanical model, combined with the coal wall rib spalling form, the failure criterion of soft rock is created, and has derived the rational supporting formula for preventing coal wall rib spalling.Thirdly, according to the analysis of7105working face strata behaviors, combined with the stress characteristics of coal wall and mechanism research of coal wall rib spalling, the specific measures to control the coal wall rib spalling and roof falling are put forward. Through the numerical simulation analysis about the grouting reinforcement to the stability of the coal wall, comparing of the regulation of stress field, displacement field, plastic field under two kinds of circumstances, the results show that, taking the coal wall of7105working face pre-grouting reinforcement measures, can greatly improve the bearing capacity of coal wall, effectively reduce the coal wall horizontal displacement deformation, greatly reduce the plastic range, significantly improve the stability of surrounding rock.