Decoupling Analysis of Interaction between Tunnel Surrounding Rock and Support in Xigeda Formation Strata

• Published in: KSCE journal of civil engineering 2021, 25(12), , pp.4897-4912
• Main Authors: Zhou, Ping, Zhou, Feicong, Lin, Jiayong, Li, Jinyi, Jiang, Yifan, Yang, Bao, Wang, Zhijie
• Format: Article
• Language: English
• Subjects: Cementation; Civil Engineering; Decoupling; Deformation; Deformation effects; Dependent variables; Dilatancy; Disclaimers; Engineering; Geotechnical Engineering & Applied Earth Sciences; Industrial Pollution Prevention; Moisture content; Parameter sensitivity; Rock; Rocks; Sprayed concrete; Steel; Steel frames; Stiffness; Tunnel Engineering; Tunnels; Water content; 토목공학
• ISSN: 1226-7988; 1976-3808
• DOI: 10.1007/s12205-021-0618-4

The Xigeda Formation has the characteristics of poor cementation, variable structure, and softening in water. It is prone to lead to failure of the initial support structures, arch collapse, and even roof fall. The key to the problem lies in the exploration of the interaction between surrounding rock and support. Therefore, based on the constraint loss theory of the tunnel face space effect, this paper constructively introduces multiple dependent variables, including the intermediate principal stress, the dilatancy of the surrounding rock, the timeliness of the shotcrete support stiffness, and the water content of the Xigeda formation, to decouple the whole process of the interaction between the surrounding rock and support, and discusses the influence of each variable. The research results show that: i) there is a critical support point in the tunnel under the influence of the unified strength theoretical parameter b and water content, and when the unified strength theoretical parameter b is constant, the critical distance of the support will decrease with the increase of the water content; ii) from the perspective of deformation control, the stress of support structure will increase with the increase of dilatancy angle of Xigeda surrounding rock; iii) considering the hardening characteristics of shotcrete, the initial support stiffness of Xigeda tunnel increases nonlinearly, and the whole process of stress and deformation can be divided into four stages; iv) the combined support structure of section steel and grille has little difference in the deformation control effect of the surrounding rock and the stress of the support structure, but the combined support structure of the grille steel frame is more sensitive to the hardening parameters.