| With the increasing depth of coal mining in China,the original rock stress and tectonic stress will continue to rise,geological conditions and mining environment are becoming more and more complex.Deep seam roadways might be subjected to non-uniform eccentric compressive stress due to the influence of geological structure,such as the geological structure of inclined coal seam,It will also be biased because of the time-varying bearing pressure caused by coal mining,and the non-uniform deformation and destruction of the roadway can be more serious.Taking Wang Jialing Mine of Shanxi Province,China as the engineering background,this paper comprehensively used the methods of model tests,theoretical analysis and numerical simulation to analyze the instability and failure of roadway under the biased pressure.Firstly,the indoor similarity model was tested to reveal the deformation and failure characteristics of the roadway under the bias pressure,and the non-uniform failure of roadway under eccentric pressure caused by abutment pressure in coal mining is emphatically analyzed.A t the same time,the forms of bias pressure that may occur in the roof of the coal roadway is induced,and the corresponding anchoring and grouting scheme was proposed for the roa dway failure under each form and applied to engineering practice in the end.The main achievements include the following aspects:(1)Similar large-scale model tests were carried out to simulate the distribution of the bias pressure above the roadway and the deformation failure of the roadway,caused by simultaneous action of the bearing pressures from horizontal and inclined coal roadways mining in adjacent sections as well as coal body mining in this section on site.The non-uniform deformation characteristics of roadway under bias pressure were also revealed.(2)With the help of 3DEC discrete element numerical software,the model was established,and the contours of bias pressure distributed around the roadway and coal pillar was drawn with MATLAB software when the coal body was mined at different distances.The common forms of the bias pressure in roadway roof were concluded into three types: V-shaped bias pressure,oblique bias pressure and roof-shaped pressure.(3)The concept of “bias difference coefficient” was put forward.By using 3DEC software,the concentrated failure area as well as the depth of plastic zone of roadway surrounding rock was simulated and analyzed under each kind of form above when the bias difference coefficient changed.With the increasing degree of the bias pressure,the evolution law of the non-uniformity of roadway deformation under three forms above was analyzed by box cha rt and the non-uniform index.(4)The concept of “supporting strengthening area(SSA)” was put forward,and determine the SSA of roadway under each form of the bias pressure.Asymmetrical bolt-grouting support for the roadway was carried out,which meant t hat on the basis of the original support,only the SSA was anchored and gr outed.Meanwhile,comparing the deformation control effects of surrounding rock between asymmetric and full-section bolting-grouting support,the superiority of asymmetric bolting-grouting support was highlighted.When the types of the bias pressure above the roadway surrounding rock are different,the failure rules are also different.In order to analyze the control effect of mechanical parameters of surrounding rock on roadway deformation under each form of the bias pressure after anchored and grouted,the simulation results of different schemes were analyzed by orthogonal experiment,where the elastic modulus(E),the cohesion(c)or the internal friction angle(j)of surrounding rock was changed.(5)A certain part of roadway was selected for anchoring and grouting construction in Wang Jialing coal mine.Through the on-site monitoring and analysis,the application effect of anchoring and grouting reinforcement was teste d and its effect was evaluated. |
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