Study On The Deformation And Failure Mechanism Of Shield Tunnel Passing The Ground Fissure By 60 Degree

In order to study the deformation and failure mechanism of the shield tunnel structure crossing Xi'an ground fissures with large angle, and to discuss the engineering measure of the Xi'an subway tunnel structure crossing ground fissures, the study uses the experiment platform which belong to Chang'an University to simulate the settlement of ground fissure, studys the destruction pattern, the destruction characteristics and the failure mechanism of the shield tunnel construct that crossed the ground fissures by 60°burying the Xi'an typical stratum during the depth of 23.0m scope, as well as carried on the contrastive analysis with 30°and 90°the operating mode under structural model experiment (with place crack included angle for 30°,90°). The strain of segment concrete, the strain of longitudinal bolt and circumferential bolt, the contact soil pressure and peripheral soil pressure, the convergence displacement of inside construct, the soil settlement on the top of model and other macrophenomena show that the main deformation and damage of segment lining structure of shield tunnel cross the ground fissure with 60 degree is shearing with distortion and bending on local; The deformation and damage range is from 0.75D (D is the external diameter of segment ring) in the hanging side to 0.50D in the lyingside;The distribution of concrete crack is near the bolt hole, and the deformation of longitudinal bolt near ground fissure is fierce shearing, with distortion and tension; The deformation and damage of segment ring is asymmetric and partial compressive; The dislocation of circumferential seam on the crown which is up to 30mm(0.025D) that is bigger than that of soffit and arch waist. It is difficult for the segment lining to apply the 20cm (0.1667D) deformation of ground fissure.Taking the physical model as the prototype and according to the related parameters of the soil that is from the crack body, it has carried on the finite element simulation using the ANSYS numerical simulation software to simulate the physical model experiment. It has obtained the more consistent destruction form and the destruction scope with the model experiment.Considering the model experiment and the finite element simulation, it is proposed that the shield part of the work under jurisdiction lining work structure is not suitable for the place crack activity intense geological environment. These conclusions will provide the theory basis for the forecast and prevention for deformation of Xi'an subway and the work under the same geological condition with large angle crossing ground fissure.