Study On Deformation Mechanism Of Soft Rock Tunnel And Support Effect Of Cable

Based on the actual engineering the support effect of lining and rock bolt sand cable is compared in this paper.Support effect of cable is one of the most important research point.Based on the analysis of continuously excavating and supporting tunnel the spatial effect of the deformation of the surrounding rock under the elasto-plastic constitutive model is roughly summarized.The support effect of the cable-lining support system in the deep-buried soft rock tunnel project is preliminarily explored.On this basis,the creep band is considered in each step of the tunnel construction process and time effect of the deformation of the surrounding rock is researched.The main content of this paper is as follows:The research status of the definition of weak surrounding rock,the mechanical properties of soft rock,the deformation mechanism of tunnel surrounding rock,the supporting theory of tunnel surrounding rock and the space-time effect in tunnel construction are Outlined.The theoretical calculation method of surrounding rock deformation is roughly introduced,mainly including the elasto-plastic model and the rheological model,focusing on the rheological model,and introducing a new fractional order Maxwell model outside the traditional model.The creep curves of the constitutive models of various rock masses under given conditions are obtained by using the numerical software FLAC^3Dand the results are compared with the theoretical calculation results.The results are quite consistent.An attempt is made to introduce the unsteady creep parameters to the fractional Maxwell model to improve its applicability and accuracy.The support effect of lining,rock bolt,cable is compared and the sensitivity analysis of the anchor cable is carried out.On the basis of this,some suggestions on the design of cable support are put forward.In elastic-plastic model,the influence of excavation on the surrounding rock mass is studied,namely the spatial effect of surrounding rock deformation.Based on the Burger creep material combination model,the influence of excavation and preliminary bracing time,excavation method and secondary lining construction time on the deformation of surrounding rock are summarized.The support design is optimized.The supporting effect is evaluated and the suggestion for forepoling is put forward.For a long time creep observation of the tunnel under different support conditions,the influence of the different support design on the early and late deformation of the surrounding rock deformation is obtained.Based on this analysis,the suggestions about the lining strength in the preliminary bracing and the secondary lining time of the soft rock tunnel under the high stress environment is given.