Study on the Impact of Shield Tunnel Under-crossing at Ground Fissure Site on Existing Utility Tunnels
(1. Department of Geological Engineering, Chang′an University, Xi′an 710054; 2. Institute of Geotechnical and Underground Engineering, Chang'an University, Xi′an 710054; 3. Technical Research Center for Urban Geological and Underground Space Engineering of Shaanxi, Xi′an 710064; 4. China Railway First Survey and Design Institute Group Co., Ltd., Xi′an 710043)
Abstract：
There is a serious safety risk when the shield tunnel at the ground fissure site crosses under the existing utility tunnels. Based on the case of the shield tunnel of Xi′an Metro Line 5 that crosses under the utility tunnel under Kunming Road at f3 ground fissure site, the finite element numerical simulation and theoretical analysis method was adopted in this paper to analyze the impact of under-crossing shield tunnel at the ground fissure site on the existing upper utility tunnel and to reveal the pattern of changes in the displacement and stress of utility tunnel structure caused by such under-crossing. The results showed that when the shield tunnel crossed the utility tunnel from the footwall to the hanging wall at the ground fissure site, the deformation of utility tunnel was increased by 30.9% compared to that on the site without ground fissure; the utility tunnel structure had a stress reduction zone (i.e. zone of influence) around the ground fissure, with an influence area covering about 4 m from the hanging wall and about 16 m from the footwall, and the side wall stress of the utility tunnel outside the stress reduction zone more than doubled compared to that at the site without ground fissure, and the bottom stress was increased by about 40%; the impacts of ground fissure on the utility tunnel structure include enlarged deformation and superposition, a reduction in the stress around the ground fissure zone, and an increase in the stress outside the zone of influence.
MIAO Chenyang1 HUANG Qiangbing1,
2 GOU Yuxuan1 TENG Hongquan3 JIA Shaochun4
.Study on the Impact of Shield Tunnel Under-crossing at Ground Fissure Site on Existing Utility Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(3): 155-165
2022, Vol. 59 