Study Of Deformation And Failure Of Roadway Surrounding Rock Containing Weak Interlayer And It's Support

With the increasing of mining depth,the influence of mechanical properties of weak interlayer in surrounding rock on deformation and failure law of surrounding rock of deep roadway is becoming more and more significant.Therefore,it is urgent to study the deformation and failure law of roadway surrounding rock considering the mechanical characteristics of weak interlayer,complex stress conditions and mining disturbance.Aiming at the problems of large deformation and difficult support of roadways with weak interlayer,taking the Liuzhuang Coal Mine in Fuyang,Anhui Province as the engineering background,using the method of combining theoretical analysis and numerical simulation,the deformation and failure laws of roadways with weak interlayer under different working conditions are studied,and the corresponding support measures are put forward.The conclusions are as follows:(1)Through the stress analysis of the roof with weak interlayer,it is found that the stress of roof strata is positively correlated with the elastic modulus E,and negatively correlated with the thickness H.Because the thickness of the weak interlayer h is very small,the stress is the largest.At the same time,because of its low strength,it is easy to damage first,and then cause the roof to fall.(2)The coal and rock mass is simplified as a shear beam bonded by weak intercalation,and the analytical solutions of displacement and stress of coal and rock mass in elastic deformation stage,plastic softening stage and sliding instability stage are obtained respectively.When the soft intercalation occurs elastic deformation and plastic softening,the displacement w of coal is positively correlated with the thickness h of weak intercalation,and the stress is negatively correlated with the thickness h of weak intercalation When the weak interlayer completely fails and the coal body slides along the weak interlayer,the change of the stress and displacement w of the coal body has nothing to do with the thickness h of the weak interlayer,but only with the thickness t of the coal body itself.(3)Using UDEC numerical simulation method,considering the lateral pressure coefficient,the thickness,location,physical and mechanical properties of weak interlayer and other factors,the numerical models of different working conditions are constructed.This paper analyzes the influence of weak interlayer,interlayer and weak layer on the deformation and failure of surrounding rock,studies the deformation and failure characteristics of coal wall surrounding rock under the joint action of weak layer and horizontal stress,and compares and analyzes the influence of weak layer in different layers on the deformation and failure of roadway surrounding rock when the lateral pressure coefficient is small.(4)According to the theory of suspension and strong wall support,an economical and reasonable bolt cable support scheme is designed,which makes the displacement of roof,floor and coal wall decrease by 22.3%,16.5% and 42.8% respectively compared with that without support;the plastic zone of roof,floor and coal wall decrease by 28.6%,25.0% and 36.8% respectively compared with that without support,and the stability of surrounding rock is greatly improved.Finally,the support parameters of the side bolt and anchor cable are optimized to further improve the support effect and economic applicability of the scheme.