Circumferential yielding lining is able to tolerate controlled displacements without failure, which has been proven to be an effective solution to large deformation problem in squeezing tunnels. However, up to now, there has not been a well-established design method for it. This paper aims to present a detailed analytical computation of support characteristic curve (SCC) for circumferential yielding lining, which is a significant aspect of the implementation of convergence-confinement method (CCM) in tunnel support design. Circumferential yielding lining consists of segmental shotcrete linings and highly deformable elements, and its superior performance mainly depends on the mechanical characteristic of highly deformable element. The deformation behavior of highly deformable element is firstly investigated. Its whole deforming process can be divided into three stages including elastic, yielding and compaction stages. Especially in the compaction stage of highly deformable element, a nonlinear stress–strain relationship can be observed. For mathematical convenience, the stress–strain curve in this period is processed as several linear sub-curves. Then, the reasons for closure of circumferential yielding lining in different stages are explained, and the corresponding accurate equations required for constructing the SCC are provided. Furthermore, this paper carries out two case studies illustrating the application of all equations needed to construct the SCC for circumferential yielding lining, where the reliability and feasibility of theoretical derivation are also well verified. Finally, this paper discusses the sensitivity of sub-division in element compaction stage and the influence of element length on SCC. The outcome of this paper could be used in the design of proper circumferential yielding lining.

Download PDF:

Keywords: Squeezing ground, Circumferential yielding lining, Highly deformable element, Support characteristic curve (SCC), Analytical method