低真空隧道环向接缝气密性能研究

Study on the Airtight Performance of Circumferential Joints in Low-Vacuum Tunnels

为探究低真空盾构隧道管片式衬砌结构环向接缝处的气密性能,以某实际工程中的垫片-垫片槽为研究对象,分别采用模型试验和数值模拟方法,研究垫片-垫片槽的气密能力、密封失效过程和密封行为。结果表明:数值模型能够准确模拟垫片-垫片槽在施工阶段压缩密封、运营前抽真空以及运营阶段升温3个阶段非线性的气密力学行为,具有可行性与可靠性;垫片-垫片接触面为垫片-垫片槽的主要泄漏路径,接触面上初始接触压力近似“W”形分布,故其密封能力主要取决于端部接触压力的大小;宏观角度上垫片密封失效可视为接触面逐渐分离的过程,而力学角度上垫片密封失效可视为接触面上最大接触压力先增加、再降至零的渐进过程;抽真空阶段在密封有效的前提下,真空力和环境温度的增加均能提高垫片密封性能。

In order to investigate the airtight performance at the circumferential joint of segment lining structure in low-vacuum shield tunnel,taking the gasket-in-groove in an actual engineering project as an object of the study,model test and numerical simulation methods are adopted respectively to study the airtight ability,the seal failure process,and the seal behavior of the gasket-in-groove.The results show that the numerical model can accurately simulate the non-linear mechanical behavior of gasket-in-groove in 3 stages:the compression sealing in construction,the vacuuming before operation and the temperature rising in operation,which proves that the model is feasible and reliable.The gasket-gasket contact surface is the main leakage path of gasket-in-groove,and the initial contact pressure on contact surface reveals approximately a“W”-shaped distribution,so its sealing ability mainly depends on the end contact pressure.From the macroscopic point of view,gasket seal failure can be viewed as a progressive process of contact surface separation;while from the mechanical point of view,gasket seal failure can be considered as a progressive process in which the maximum contact pressure on the contact surface first increases and then decreases to zero.In the vacuumizing stage,under the premise of effective sealing,both the increase of vacuum force and ambient temperature can improve the sealing performance of the gasket.