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Geomechanics and Engineering
  Volume 11, Number 1, July 2016, pages 117-139

Deformation analyses during subway shield excavation considering stiffness influences of underground structures
Zhi-guo Zhang, Qi-hua Zhao and Meng-xi Zhang

    Previous studies for soil movements induced by tunneling have primarily focused on the free soil displacements. However, the stiffness of existing structures is expected to alter tunneling-induced ground movements, the sheltering influences for underground structures should be included. Furthermore, minimal attention has been given to the settings for the shield machine's operation parameters during the process of tunnels crossing above and below existing tunnels. Based on the Shanghai railway project, the soil movements induced by an earth pressure balance (EPB) shield considering the sheltering effects of existing tunnels are presented by the simplified theoretical method, the three-dimensional finite element (3D FE) simulation method, and the in-situ monitoring method. The deformation prediction of existing tunnels during complex traversing process is also presented. In addition, the deformation controlling safety measurements are carried out simultaneously to obtain the settings for the shield propulsion parameters, including earth pressure for cutting open, synchronized grouting, propulsion speed, and cutter head torque. It appears that the sheltering effects of underground structures have a great influence on ground movements caused by tunneling. The error obtained by the previous simplified methods based on the free soil displacements cannot be dismissed when encountering many existing structures.
Key Words
    shield tunneling; stiffness influence; shield propulsion parameters; simplified theoretical method; 3D FE numerical simulation; case study
(1) Zhi-guo Zhang:
School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China;
(2) Zhi-guo Zhang, Qi-hua Zhao:
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China;
(3) Zhi-guo Zhang:
Key Laboratory of Geohazard Prevention of Hilly Mountains, Ministry of Land and Resources, Fuzhou 350002, China;
(4) Meng-xi Zhang:
Department of Civil Engineering, Shanghai University, Shanghai 200072, China.

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