Study On The Creep Deformation Of The Foling Tunnel's Broken Surrounding Rock Mass

ABSTRACT:With the rapid development of highway construction, a great number of highway tunnels have been constructed or under construction, and it will inevitably encounter, such as soft rock, faults, joints, fractures and soft interlayer and other adverse geological conditions;"New Austrian Tunneling Method," the application and promotion gives supporting structure a new support concept, when the tunnel goes through the fracture zone, the rock mass and tunnel structure are suffered complex and variable force, it is difficult to grasp how the creep displacement will grow.Existing theories are all against the circular tunnel under hydrostatic pressure, as to the creep deformation analysis of non-circular tunnel is also rare. Based on the problems above-mentioned, this thesis set the reserch around the subject of the creep deformation of the Foling tunnel's broken surrounding rock mass, the main work is as follows:1 Physical and mechanical properties tests of the surrounding rock mass from the fracture zone of the Foling tunnel, including the density test and uniaxial compression test which is to obtain the stress-strain curves and uniaxial compressive strength, elastic modulus, Poisson's ratio and other mechanical properties parameters;2 Uniaxial compression creep test of the surrounding rock mass from the fracture zone of the Foling tunnel, get the stress loading curve and the creep curve and then to fit the results with the Burgers creep law to obtain the Brugers model parameters by nonlinear least squares method;3 Use the complex function to derive the elastic analytical solution of the displacement of the circular carvern.Work out a fortran program to solve the coefficient of mapping funtion which turn a three center circle area into ta circular area by the conformal transformation method. Then use the "elastic-viscoelastic flexibility" correspondence principle to derive the viscoelastic analytical solution of the displacement of the Foling tunnel's broken surrounding rock mass which corresponds to the displacement of Burgers model.4 Use the FLAC3D software to simulate the actual situation, obtained the settlement of tunnel crown, indented side wall and the dome uplift displacement after three decades, the analysis shows:for the soft rock it must consider the rheological properties, which restricts the stability of the tunnel structure to a large extent.