| Based on the research background of disturbed section of west-wing air intake roadway in Yuwu Coal Mine,the instability mechanism of roadway,different floor heave control technology and mechanism of yielding bolt are analyzed by means of numerical calculation,theoretical analysis and mechanics deduction.The combined support technology of U-shaped steel reverse bottom arch with grouting bolt and top-wall yielding bolt for roadway is put forward,which is verified by industrial test..The main research results are as follows:(1)Under the influence of repeated disturbance of working face,the internal stress of lining structure presents obvious non-uniformity.Tensile stress concentration occurs at the top,shoulder and bottom of roadway,and shear stress occurs at the arch shoulder.Through the analysis of the stress characteristics of the anchor cable,it can be concluded that the anchor cable located at the high stress concentration of surrounding rock will first be destroyed.After the failure of the local support structure,the deformation of the local surrounding rock will intensify,which will gradually lead to the failure of the whole support structure and the instability of the surrounding rock.(2)Based on elastic-plastic theory,the mechanics model of roadway floor heave is established,and the theoretical formula of floor maximum depth is deduced by combining the slip line field theory.The failure depth of the West Wing intake roadway is calculated to be 4.5m.At the same time,the relationship curves of floor maximum failure depth with the stress of surrounding rock,friction angle of rock mass and cohesion are analyzed by VB.The results show that the roadway floor is affected by three factors: stress of surrounding rock,friction angle of rock mass and cohesion.The failure depth is positively correlated with the stress of the floor surrounding rock,negatively correlated with the cohesion c and the angle of internal friction of the floor rock,which provides a theoretical basis for the control mechanism of the floor in the future.(3)The stress distribution,deformation and failure characteristics of surrounding rock at the depths of 1.0m,1.4m,1.8m and 2.2m are studied by numerical calculation method.The control effect of roadway floor is analyzed when the size of relief groove is different.The results show that with the increase of the depth of relief groove,the deformation of roadway floor decreases gradually,while the relief groove tends to close,but the roof subsidence and two sides of roadway are different.The relative closeness will increase gradually.(4)Taking the original supporting scheme as the contrast scheme,the paper compares and analyses three new supporting schemes of floor.The analysis results show that the bolt-grouting support is excluded from controlling the deformation of roadway floor.According to the influence of the surrounding rock of the whole roadway,"pressure relief groove + grouting bolt" will affect the stability of the surrounding rock of both sides and roof of the roadway,while "inverted bottom arch + grouting bolt" will be in a stable state by controlling the floor.Finally,combined with the stress distribution and failure characteristics of surrounding rock,it is determined that the floor control scheme is "U-shaped steel reverse bottom arch + grouting bolt" combined support.(5)By means of numerical simulation,the stress variation law of bolts under different yielding distances is analyzed.When the yielding distance is 0 mm,the stress of bolts in the stress concentration area of roadway surrounding rock exceeds the breaking load.When the yielding distance is increased to 20 mm,all bolts are effectively protected.Therefore,the yielding distance of bolts is 20 mm.The deformation law of surrounding rock under different yielding pressure distance is analyzed,and it is concluded that the deformation of surrounding rock decreases first and then increases with the increase of yielding pressure distance. |
PDF Full Text Request