Research Of The Stability And Reliability Of Surrounding Rocks In The Process Of Gonghe Tunnel's Construction

The geological conditions of Gonghe tunnel are very complex. It meets the special geological disease which is the soft rock large deforming, when the tunnel was constructing. To get the mechanism of the special geological disease and design the reasonable initial support, this paper has done research in the following areas:①Stability of surrounding rocks's researching methods, monitoring measurement in tunnel and reliability's research status are analysed and summarized, main research contents and technical routes are given.②Test on the mechanical properties of the rock tunnel, and the uniaxial compaction test, the triaxial test, the water-saturated soften rock test are completed. The basic mechanics parameters of the surrounding rock are got, the rigidity and strength are a little low. The change rule of shale Dynamic elastic modulus and uniaxia compressive strength whit water-saturated time is got. The rock soften equations are got. Through creep test of the surrounding rock The creep rules of Shale under the 15MPa, 20 MPa, 25 MPa and 30 MPa pressure and corresponding creep constitutive equations and parameters are got.③The constructing process of the Gonghe tunnel's cracked segment is studied by FEM. The evolution process of the stress in the surrounding rock, the possible broken mode of the surrounding rock, the impact of the depth of the tunel on the tunnel distortion and the force situation of the supporting structure in tunnel are analyzed.④The New Austrian Tunneling Method is briefly introduced, Through monitoring measurement of gonghe tunnel,the laws of convergence of the surrounding rock displacement, axial force of anchor bolt, contact stress and I-stress are got. Combined with FEM results, we give the best support scheme.⑤Using basic principle and methods of structural reliability analysis, the limit state equation of tunnel initial support's reliability analysis is established. Using Probabilistic Design System in ANSYS, Monte Carlo Method was selected to make sample calculation for 8000 times. The reliability of integral primary support in tunnel is analysed and evaluated.