Study On Longitudinal Displacement Profiles Of Tunnels Based On Hoek-brown Failure Criterion

Convergence-confinement method is widely used in tunnel support structure design and stability analysis because it can directly reflect the interaction between surrounding rock and supporting structure.Longitudinal displacement profiles(LDP),ground response curve(GRC)and support characteristic curve(SCC)are three major components of the convergence-confinement method.Here LDP represents theconfinement characteristics of the tunnel face.The early displacement can be obtained by coupling LDP with GRC,and it provides theoretical basis for the erection time and stability analysis of supporting structure.Much study has been carried out on GRC and SCC,making a lot of achievements.However,research on LDP is relatively inadequate.Therefore,based on the Hoek-Brown failure criterion,the longitudinal displacement profiles are studied by numerical simulation.Firstly,based on the domestic and external theoretical achievements about the convergence-confinement method and the longitudinal displacement profiles,a comprehensive overeview of its basic principles and main constituent elements has been made.Its development history and research status also have been made.Considering the convergence-confinement method,the stability coefficient of supporting structures is established.Then,based on the Hoek-Brown failure criterion and numerical simulation,the parameter of rock mass to the LDP are studied.The regulities of the displacement release coefficient varied with the Poisson's ratio,deformation modulus,intact rock strength,Hoek-Brown material constant,GSI and disturbance of rock mass are obtained.Next,the properties of the LDP under gravitational stress field and several simple tectonic stress fields are discussed.Research results shows that:in gravitational stress field,the maximum displacement of tunnel wall,displacement release coefficient in tunnel face and rock mass disturbance range was increased significantly compared with the hydrostatic stress field;when the horizontal stress is greater than the vertical stress,the deformation of the tunnel side wall is larger than that of the vault;when the tunnel excavation direction perpendicular to the maximum principal stress direction,the tunnel wall deformation increased significantly;under the non hydrostatic stress field,the deformation process of the tunnel vault,side wall and arch bottom is different.Further,based on quadratic regression orthogonal design,the construction method of displacement release coefficient formula is given,a series of numerical experiments of circular tunnel in hydrostatic stress field have been carried out with the method.The regression equation of displacement release coefficient was established and the sensitivity of parameters are determined.Through analysis of numerical examples and a case history,the equation is proved to be reasonable and effective.Lastly,according to the similarity theory,an indoor similar model test research by considering the three-dimensional effects is constructed.After the cavern excavation,the strain of tunnel vault behind the tunnel face is monitored and the experimental data were analyzed.