An Investigation Into Elastic Solution Of Stress Field Around Rectangular Roadway And Width Of Plastic Zone

Due to the close link between the stress distribution around underground space(with related structures) and their stabilities, solution of stress distribution is of great significance in underground engineering. As the important path for transport of materials and coal, the stability of underground roadway and corresponding support structures play a vital role in the safe and high-efficiency mining. Based on the local geological and technical conditions in Xinrui coal mine, this thesis investigates the stress distribution and width of plastic zone in the ground of rectangular roadway by utilizing analytical and numerical methods. The main achievements are as follow:1) General expressions of the stress components ?? 、?? 、??? in ζ for the ground of roadway with arbitrary aspect ratio under arbitrary biaxial far-field uniform pressure are got by using complex variable theory. The transformation formulas for stress components from ζ-plane to z-plane are also presented systematically. The vertical, horizontal and shear stress along the level of roof or floor and centroid of rectangular roadway with different aspect ratio(1.0:1 to 5.0:1) are shown and analyzed. The corresponding results are also verified by FEM program.2) The link between the stress distribution in the elastic part of the ground and the elastic solution is established based on a postulation. Combing the gravitational balance formula and hypocritical linear relation between the vertical stress and distance from underground openings, a novel mechanical model is constructed to analyze the width of plastic zone around underground rectangular opening. The relationship between width of plastic zone, stress concentration and stress provided by the coal wall(residual strength) is analyzed. The width of plastic zone of the roadway in 5# coal seam in Xinrui coal mine under different ground strength are computed and compared with the results from FLAC3 D. The errors between the analytical and numerical results are analyzed.3) Numerical results shows: at the level of centroid, with the decrease of strength of coal, the initial value of vertical stress curve, i.e. the bearing capacity of coal wall, decrease while the stress concentration increase and the peak of vertical stress move into the deeper part of the ground, which means the increase of width of plastic zone; at the level of roof or floor, with the decrease of strength of coal, both the bearing capacity of coal wall and the stress concentration decrease, and the peak of vertical stress move into the deeper part of, which also means the increase of plastic zone. In addition, with the decrease of strength of ground, both the range and degree of the influenced ground in the side and front or back of the driving working face increase.