Experimental study on articulated design of mountain tunnel crossing strike-slip fault zones
Du Xiuli1 Wang Zhen1 Zhao Mi1 Zhong Zilan1 Wang Hongru2 Sheng Qian3
1. Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing 100124, China;
2. China Construction Industrial Engineering and Technology Research Academy Co., Ltd., Beijing 101300, China;
3. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
Abstract：Mountain tunnels in western China usually intersect with the active fault zones during the processes of route selection, and the challenges of fault movement posed to structural design and safe operation have to be faced. The Xianglu mountain tunnel, which is the first portion of the Dianzhong water diversion project, is taken as an example in this study. Based on the new experiment equipment for simulating strike-slip faulting, the rupture characteristics of rock masses and the response characteristics and failure modes of the tunnel model with articulated design are investigated. The results show that the displacement of ground surface under strike-slip fault movement has obvious discontinuity at the fault slip surface. The cross-section of the tunnel intersecting with the fault slip surface changes from the circular shape to the vertical ellipse, and the rate of diameter deformation of the horizontal axis reaches 6.57% under a given fault displacement of 50 mm. The segment lining has a horizontal deflection of about 5° under strike-slip faulting, and meanwhile there is an obvious misalignment between the adjacent segment linings. Compared with the continuous tunnel, the articulated design can significantly reduce the strain response of the lining structure. Furthermore, circumferential and oblique cracks dominate the failure modes of tunnel in articulated design, which are significantly smaller than those of continuous tunnel in terms of damage extent and range.
