Analysis of the whole-process mechanical response of tunnel surrounding rock under the effect of anchorage system

The tunnel anchoring system is an important means to control the deformation of surrounding rock, whose scientific design lies in the full understanding of its mechanism. In this paper, the whole process of the response of tunnel surrounding rock with the action of the anchorage system is analyzed. Based on the space effect of the tunnel face, the displacement releases of surrounding rock at bolt and anchor cable installation and the effect of their relative lengths are considered. According to the relationship between the anchorage zone and the plastic zone of the interaction between the anchorage system and the surrounding rock, six mechanical analytical models of the whole process evolution mechanism of anchorage system are proposed and analyzed respectively. The solutions of tunnel deformation, plastic radius and stress field of surrounding rock under the action of anchoring system are obtained. The correctness and reliability of the proposed model are verified through a comparison with numerical simulations using typical examples. Furthermore, the deformation control effect of the anchorage system and its influencing factors are analyzed, and the respective tasks and objectives of rockbolts and anchor cables are defined. The safety reserve function of anchor cable is clarified, giving a new understanding of deformation control principle of anchorage system. The research results lay a theoretical foundation for the quantitative design of tunnel anchorage system and provide a new idea for the control of large deformation of tunnel surrounding rock. Copyright ©2022 Engineering Mechanics Press. All rights reserved.