Development and application of the integrated sealant test apparatus for sealing gaskets in tunnel segmental joints

Abstract

An innovative apparatus has been developed in this study to investigate the coupled leakage and mechanical behaviors of gasketed segmental joints, subjected to the field loading conditions during the construction and operation stages. The basic principles and detailed configurations of this newly developed test setup are presented in detail. The test apparatus can be used to accurately monitor the water leakage pressure of segmental joints under various combinations of joint openings and offsets. A series of test sets, based on different characteristics of sealing gaskets used in segmental joints, were subsequently conducted to evaluate the functionality of the test setup. Testing apparatus was designed to evaluate the waterproof capacity of the three types of segmental joints (i.e., longitudinal/circumferential joint and T-joint (intersection of longitudinal and circumferential joints)) in the Nanjing Weisan Rd. Tunnel. The tested segments were cast with the identical gasket groove details and flanks to the practical tunnel segments. The correlation between gasket contact stress and supplied water pressure was analyzed. Comparison of the gasket sealant and mechanical behavior showed that there existed a “correlated zone”. The results showed that gasket-gasket interface, gasket-concrete gasket groove interface, damaged zones, and frame corners were the potential places of leakage in segmental joints. Finally, the results demonstrated that local concrete damages around the groove flank could serve as a water leakage channel and reduced the sealant performance of gasket.