Experimental Study on Mechanical Behavior of Gas Transmission Shield Tunnel Segments

Abstract

To analyze the mechanical behavior of the shield tunnel segment lining of underwater pipelines, based on the prototype segment structure practically applied in a project, a local model test of the combined shield segment considering front and rear ring staggered joints was designed. The internal forces and strains, joint opening and misalignment, and structural deflection change with the axial pressure ratio at different locations of the segment in the range of axial pressure ratio 0.02–0.54 were investigated, and the final failure form of the segment structure was also obtained. The experiment results show that in the assembly segments, the middle segment has the highest stiffness, followed by the side segments. When the segments are damaged, the maximum opening of the longitudinal joint is 1.75 mm. Because the overall damage of the segments is earlier than the joint damage, it is suggested that the development of structural cracks, joint misalignment, and structural deflection be taken as the basis for evaluating the safety of tunnel segments. When the axial compression ratio is loaded above 0.50, top concrete crush damage occurred in the middle segment, while the concrete on both sides happened to incur an oblique 45° shear damage.