Experimental investigation on the damage evolution and failure mechanism of segmental joints based on DOFS and AE

Abstract

The damage evolution and failure mechanism of segmental joint are of great significance for the design and safety assessment for segment structures. In this study, a series of full-scale loading tests on the segmental joints adopted by the Jinan Yellow River Tunnel under positive bending loading scenario (PBLS) and negative bending loading scenario (NBLS) were conducted, introducing new measurement scheme combining distributed optic fiber sensor (DOFS) and acoustic emission (AE). The joint deformation, AE parameters, concrete strain, bolt strain and reinforcement strain are investigated. The test results show that the deformation and failure process of the joint can be divided into four stages and three stages under PBLS and NBLS, respectively. The compression-shear failure caused by the shear cracks is considered as the main failure mode of the segmental joints, and the development rate of the crack width under PBLS is obviously larger than that under NBLS. The maximum bolt strain usually occurred at the edge of the thread instead of the joint surface. The bolt under NBLS yields later than that of PBLS. Due to stress concentration, the maximum tensile strain of reinforcement under PBLS and NBLS is located near the hand hole and sleeve, respectively.