Stress and Deformation Characteristics of the Tunnel in High In-situ Stress Fault Fracture Zone
In order to address the problems of large deformation of the surrounding rock,cracking of concrete and deformation of the arch when the tunnel crosses in-situ stress fault fracture zone,relying on Xiangjunshan Tunnel project,the tunnel deformation and force characteristics caused by excavation of different grades of surrounding rock sections in and around the fault fracture zone were analyzed through field tests.The study shows that:Before the lower stage excavation,the tunnel vault settlement and upper stage convergence both reached 70%of the peak,and the convergence deformation at the fault fracture zone showed an obvious phenomenon of"big on the top and small on the bottom",while the subsidence of the section near the fault fracture zone showed an obvious symmetry phenomenon.The maximum settlement value was 73.4mm in the tunnel fault fracture zone,at the top of the tunnel vault,and localized cracking of the shotcrete and distortion of the steel frame were observed.In the subsequent construction,it was recommended to adopt the double-layer initial support scheme of"soft first,then rigid".The surrounding rock pressure presented a discrete distribution in space,and the surrounding rock pressure was asymmetrically distributed in the fault fracture zone and its adjacent sections.There was no large tensile stress zone at the arch foot and side wall,and the stress on the arch was obviously greater than that on the arch top,indicating that the horizontal structural stress was obvious.The deformation of the surrounding rock and the stress characteristics of the initial support of the tunnel in the fault zone were mainly determined by the regional tectonic stress,the maximum principal stress and the comprehensive structure of the rock mass.The deformation and initial load of the surrounding rock in the fault fracture zone reflected the initial deformation of the surrounding rock to some extent.
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NSTL
万方数据
维普
