Prestress Of Rock Bolts Anchored In Rock Mass Under Shear Creep Research On Loss Law

In order to study the law of prestressing loss of anchors in deep jointed rock masses,similar materials are used to simulate the prestressing loss of anchored jointed rock masses under shear creep along the joint surface,and the gray strip method is used to prestress under different influencing factors The sensitivity of the loss is analyzed to find out the most influencing factors of the sensitivity parameter,which is substituted into the compound rheological model,constructing a constitutive model describing the coupling of the prestressing loss of the rock bolt and the rock shear creep,and solving the relevant equations.The anchoring effect of prestressed anchors was analyzed.Based on the local deformation theory of the anchor-slurry interface,the hyperbolic function of the axial force transmission law of the anchoring section of the prestressed anchors was revised and established,and its influencing factors were analyzed.The numerical experiment is used to analyze the coupling effect between the shear creep deformation and the prestress loss of the anchored through-joint rock mass.The conclusions obtained are as follows:(1)The initial value of prestress,rock mass strength and bolt diameter as the influencing factors of the bolt prestress loss curve all include three stages of prestress drastic decline,prestress fluctuation and prestress stability.(2)Compared with the bolt diameter and rock strength,the sensitivity coefficient of the initial value of the prestress is at most 0.77,which is the factor that has the largest impact on the prestress loss.(3)The accuracy of the compound rheological model is verified through laboratory tests and shows that the model is superior to the traditional model.Therefore,it provides a theoretical basis for studying the prestress loss of the anchor rod,and provides a new idea for the stable reinforcement of the rock mass.(4)According to the stress characteristics of the bolt during the test,based on the local deformation theory of the anchor-slurry interface,the hyperbolic function of the axial force transfer law was revised,and the elastic modulus E,radius r,length l and virtual coefficient T of the bolt were studied and analyzed.Influence of axial force distribution.The mechanism of the coupling effect between the creep deformation of anchored rock mass and the prestressed loss of bolt is clarified.The creep model of the coupled effect of creep deformation of anchored rock and the prestressed loss of bolt is established and the relevant parameters of the model are obtained.Calculation method of prestress loss.(5)Through the numerical simulation,the whole process of the shear creep test was simulated,and the coupling effect of the shear creep deformation and the prestress loss of the anchor rod of the anchored through-joint rock mass was analyzed by the numerical test.