Rock and Soil Mechanics ›› 2020, Vol. 41 ›› Issue (3): 1039-1047.doi: 10.16285/j.rsm.2019.5545

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Study on the mechanism of circumferential yielding support for soft rock tunnel with large deformation

LEI Sheng-xiang1, 2, 3, ZHAO Wei1, 2   

  1. 1. School of Civil Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China 2. Key laboratory Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China 3. China Railway Construction Corporation Limited, Beijing 100855, China
  • Online:2020-03-27 Published:2020-09-27
  • Contact: ZHAO Wei, male, born in 1977, PhD candidate, Senior engineer, mainly engaged in the analytical work of tunnel and underground engineering. E-mail:
  • About author:LEI Sheng-xiang, male, born in 1965, PhD, Professorate senior engineer, doctoral supervisor, mainly engaged in the technical development and management of tunnel and underground engineering.
  • Supported by:
    This work was supported by the National Key R&D Program of China(2018YFC0808702,2018YFC0808706) and the Open Fund for Strengthening Engineering Materials and Structures in Key Laboratories of Universities in Fujian Province(B170001-1).

Abstract: It is difficult for traditional bolt-shotcrete support to meet the requirements of deformation control in soft rock tunnel, therefore yielding support becomes an important means to control deformation. The circumferential yielding support sets up the yielding device in the circumferential direction of the tunnel in order to realize the rigid-flexible-rigid characteristics of the supporting structure. From the perspective of energy transformation in tunnel excavation-support process, the principle of circumferential yielding support is clarified in this paper. The main factors affecting the deformation of the support structure are analyzed using the analytical method of structural mechanics, and the mechanical characteristics of traditional support and circumferential yielding support are compared using the finite element software - ABAQUS. The following conclusions are drawn: (1) The initial support is a typical compression-bending member. The circumferential yielding support causes the yielding device to buckle through the circumferential pressure, which balances with the internal force of the support structure. It is hence possible to achieve a certain support resistance while controlling the surrounding rock stress by shortening the circumference. (2) The circumferential yielding device should be set at places where the bending stress is relatively small. The shear stiffness and bearing capacity of the device should be ensured with the characteristics of "strong shear and weak compression". (3) The circumferential yielding support has the mechanical characteristics of rigid-flexible-rigid, which can be adapted to the rheological characteristics of soft rock with high geo-stress.

Key words: soft rock tunnel, large deformation, circumferential yielding support