Experimental and numerical study on waterproofing performance and leakage mechanism of bell-and-spigot joints in prefabricated utility tunnels

In order to explore the waterproofing mechanism of F-type socket joint in rectangular pipe jacking tunnel, full-scale tests and finite element numerical calculations were conducted to analyze the sealing performance and failure modes of rubber rings with different heights under different water pressures, revealing the distribution law of contact stress and leakage mechanism of rubber rings. The results show that low-height rubber rings experience leakage at a water pressure of 0.2–0.3 MPa, while the waterproofing ability of medium and high height rubber rings is significantly improved, withstanding 0.7 MPa and 1.0 MPa water pressure, respectively. The 28 mm rubber ring still has no leakage at a 1.6 MPa water pressure. At 0.4 MPa water pressure, the height of the rubber ring increases from 22 mm to 24 mm, the proportion of effective contact stress increases from 35.7% to 78.6%. The waterproofing performance of tunnel joints is jointly determined by the rubber ring height and the proportion of effective contact stress. No leakage occurs at the pipe gallery joint when the proportion of effective stress exceeds 70%. This research provides a theoretical basis for the size selection of waterproofing rubber rings for the rectangular pipe jacking tunnel.