Abstract
The segment lining structure physical modeling experiment of shield tunnel cross the ground fissure with 30° is designed according to the similarity theory, which based on the Xi’an metro engineering and the geological environment of Xi’an ground fissure. The strain of segment concrete, longitudial bolt, and circumferential bolt, the contact soil pressure and peripheral soil pressure, convergence displacement of segment lining, the soil settlement on the top of model and other macrophenomena show that the main deformation and damage modes of segment lining structure of shield tunnel cross the ground fissure with 30° is shearing with distortion on local; the deformation and damage range is from 1.25D (D is the external diameter of segment ring) in the hanging side to 0.75D in the lying side; the deformation and damage of segment ring is asymmetric and partial compressive; the dislocation of circumferential seam on the soffit which is up to 40mm(0.033D) is bigger than that of crown and arch waist. It is difficult for the model to apply the 20cm(0.1667D) deformation of ground fissure, and the segment lining structure of shield tunnel is unsuitable to the geological environment with violent activity of ground fissure.
1. INTRODUCTION
Shield tunnel structure is widely used in the urban area, because of its small influence to the surrounding environment, little pollution and fast speed. Lining segment structure of shield tunnel belongs to flexible structure. Its deformation in response to the force, because of the subside of stiffness of bolt joint, is clearly different from the integral tunnel lining structure. Furthermore, due to the special geological environment, there are more than 10 existing ground fissures in Xi’an area and their activity is in progress at present[1]. Lining segment structure of tunnel is potentially in great danger. The angle of intersection and the distance between the ground fractures greatly affect the severity of the damage. At the same time, the stiffness and strength of the structure also play an important role on the extent and other regularity of damage.
