Analytical solutions and in-situ measurements on the internal forces of segmental lining produced in the assembling process

Abstract

Most of the traditional design methods assumed shield tunnel lining as a perfectly formed ring, without special attention to the effect of pre-deformations and inaccuracies produced in the assembling process before the segmental ring is closed. However, these factors can significantly affect the mechanical performance and durability of the tunnel. To make up for the deficiencies of conventional design models, we contributed a new method to evaluate the internal forces of tunnel lining produced in the assembly, in which the key idea is to appropriately assume the assembly tolerance of bolt holes and pre-deformations of the lining ring. By applying the principle of minimum potential energy, analytical solutions for three cases (ALS-FF, ALS-FC, ALS-CC) were developed to determine the internal forces of segments produced in the assembly process. Then, an in-situ measurement was conducted to validate the method, and it showed a favorable agreement with the theoretical results. Furthermore, the critical parameters of the proposed model were verified by parametric studies, which revealed that the higher the tolerance space Tsp, the lower the internal forces induced by the assembly inaccuracy. According to the research results, the reasonable tolerance space Tsp and other critical design parameters can be determined for a shield tunnel to achieve optimal performance. The simplicity and practicability of the analytical method, as well as the quantitative evaluation of the effects of assembly inaccuracy on tunnel lining, would undoubtedly contribute to the improvements and optimizations of the design of segmental tunnel lining.