Determination Of Reasonable Parameters For Nonhomogeneous Support Of Prestressed Anchor(Cable) In Deep Soft Rock Roadway

The mining of coal mine has entered the deep part of the mine,where the high ground stress and the poor surrounding rock properties make the support more difficult.With the introduction of anchor support,the active support theory has rapidly become the main theory in China.Combined with the progress of a large number of theoretical research and engineering experience has got a conclusion that the combined support method with anchor(cable)support has become the mainstream support technology.Therefore,this study takes the Huabei Yuandian mine east wing return air roadway as an example,whose surrounding rock mainly consists of sandstone and mudstone.According to the field measurement results,it can be concluded that in the sandstone roadway,the surrounding rock can be in a stable state by using the conventional support scheme.Therefore,this study mainly discusses the optimization of the support scheme for the deep buried mudstone roadway.Because the support effect of the previous conventional support form to the deep hard rock roadway is obvious while the support effect to the deep soft rock roadway is not ideal.Therefore,this study changes the traditional support concept of equal spacing,equal length and equal pretension,and adopts the non-uniform support method to ensure the stability of the roadway side.This study simulates the influence range of the additional stress by the numerical value produced by the bolts(cables)with different parameters in the mudstone roadway side,and calculates the displacement distribution of the roadway side to reasonably determine the supporting parameters.In the meantime,it can ensure the additional stress in the large displacement area of the roadway side can be effectively superposed.Finally,the study determines the scope of the loose broken circle of the roadway side adopting the numerical analysis to fit the displacement curve.Starting with the influence range of additional stresses,this sutdy studies the influence range of the additional stress by using numerical simulation produced by the bolts(cables)with different parameters in the roadway side,simulates and calculates the displacement distribution of the roadway side to reasonably determine the support parameters,and ensures the effective superposition of the additional stress in the area with largedisplacement of the roadway side.In the numerical analysis,the displacement curve is fitted to determine the scope of broken circle of loose rock in the side of roadway.The simulation results can be concluded that the influence range of the additional stress of the anchor(cable)is basically unchanged,but the effective range of it will change accordingly.The effective range of the additional stress is similar to the cone,which can be determined by the value of Tecplot slice.The size of additional stress is related to the length of anchor(cable)and the size of pretension.Besides,the effect of pretension on additional stress is the most obvious,and the range and value of additional stress field produced by anchor cable is larger than that of anchor.The displacement of vertical wall semi-circular arch roadway is mainly distributed above the vertical wall without support,which is controlled by setting different parameters of anchor(cable)at the position with larger displacement.The relationship between displacement and bolt length is fitted by the quadratic curve,which is analyzed quantitatively by curve equation with the allowable deformation of roadway,aiming at the different allowable deformation of the roadway with different functions to adjust the bolt paremeters.In the end,this study takes the bulking coefficient of broken expansion of the surrounding rock as the evaluation standard of the broken state of the surrounding rock,which uses the displacement regression equation of different positions of the side of the roadway combining with the bulking coefficient to deduct the conclusion,which analyzes the size of the broken circle range and the loose circle range of the side of the mudstone roadway.Compared with the traditional support scheme,using the non-uniform support and the classical support scheme is of high value for the superposition of the additional stress of the roadway side,the change of the displacement field and the change of the loose broken circle.Besides,adopting the non-uniform support scheme will greatly improve the reduction of displacement and the uniformity of deformation of the side of the roadway.Meanwhile,the range of the broken circle of the surrounding rock in the side of the roadway reduces to a certain extent,whose loose range also reduces to a great extent.Therefore,adopting the non-uniform support provides this study with a relatively new idea.Figure 130 Table 24 reference 53...