Title:
Debonding and Control of Shield Tunnel Strengthened with Thin Plate (Prepublished)
Author(s):
Dejun Liu, Xiaoyun Yao, Qingqing Dai, Cong Tian, Jiangwen Zheng
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
anti-debonding measures; cohesive zone model; inner surface reinforcement; interface debonding; numerical analysis; shield tunnel
DOI:
10.14359/51746813
Date:
5/14/2025
Abstract:
Inner surface reinforcement is one of the most widely adopted techniques for upgrading or strengthening shield tunnels. An important failure mode in this method is the debonding of the thin plate from the segments, resulting in less reinforcement effect than expected. The shield tunnel lining is a discontinuous curved structure formed by connecting segments with bolts, and its structural form and internal force state are essentially different from reinforced concrete beams. However, there are few reports on the evolution process of debonding failure of similar structures. Therefore, to develop a thorough understanding of the debonding failure, a three-dimensional refined numerical model for the shield tunnel strengthened by a thin plate at the inner surface based on the mixed-mode cohesive method was proposed. The validity and rationality of the model were corroborated by a full-scale experiment. Then, the model was applied to other inner surface reinforcement schemes commonly used in practice to explore the debonding mechanism of the adhesive layer. Finally, anti-debonding measures were proposed, and their effectiveness was elucidated by numerical analysis. The results show that the proposed numerical model can accurately predict the failure process of the adhesive interface of the shield tunnel strengthened by a thin plate. There are obvious interfacial stress concentrations at the joints and the plate ends, which are the essential reasons for the debonding failure initiating from those places. Anchoring the thin plate only at the plate ends and joints can significantly and sufficiently increase the debonding load. Therefore, it is not necessary to add anchoring measures elsewhere.