考虑水压作用过程的盾构隧道接缝防水机制研究

Study on Waterproof Mechanism of Shield Tunnel Joints Considering Water Pressure Process

为研究盾构隧道管片接缝处弹性密封垫在水压作用下的防水机制,在对管片拼装至隧道发生渗漏期间水压作用过程进行分析的基础上,采用有限元分析软件建立流固耦合计算模型,对水体渗入接缝弹性密封垫的过程进行动态化模拟,结合密封垫防水性能试验,揭示密封垫防水能力的发挥过程及产生机制,并对双道弹性密封垫防水可靠性增加的原因进行探讨。结果表明:1)流固耦合模型能够较为直观、精细地模拟水体突破弹性密封垫的过程。2)从管片拼装到隧道渗漏的过程中,弹性密封垫经历了管片挤压-外水推挤-水体楔入-水体突破4个阶段。3)当水压p w<p=α(p 0+p 1)时,水体作用于密封垫迎水面外侧,这时密封垫的防水能力仍然具有较大的冗余;当水压α(p 0+p 1)<p w<α(p 0+p 1+p 2)时,水体虽然发生楔入,但不能完全突破密封垫,仍然存在一定的防水能力;当水压p w>α(p 0+p 1+p 2max)时,水体突破密封垫,发生渗漏。4)由于双道弹性密封垫之间存在储水空腔,空腔中的水压作用于第1道弹性密封垫的背水侧,产生的接触应力增量可引起第1道弹性密封垫的"自愈",因而能够在一定程度上增加防水的可靠性。

The waterproof mechanism of elastic sealing gaskets under water pressure is not clear.Hence,based on the analysis of the process of water pressure action from segment assembly to tunnel leakage,the fluid-solid coupling calculation model is built by finite element analysis software to simulate the dynamic process of water seeping into joint elastic gasket.And then by conducting the waterproof performance test of joint sealing gasket,the process and mechanism of waterproof performance of gasket are explained,and the causes for the increased reliability of double elastic sealing gasket are discussed.The results show that:(1)The fluid-solid coupling model can directly and finely simulate the process of water breaking through elastic gasket.(2)During the process from segment assembly to tunnel leakage,the elastic gasket experiences four stages,i.e.segment extrusion,external water pushing,water wedge and water breakthrough.(3)When the water pressure p w<p=α(p 0+p 1),water acts on the outside of the gasket face,and the waterproof capacity of gasket still has large redundancy;whenα(p 0+p 1)<p w<α(p 0+p 1+p 2),the sealing gasket is not broken through by the water which wedges in and still has waterproof capability;and when the water pressure p w>α(p 0+p 1+p 2max),the sealing gasket is broken through by the water and the leakage happens.(4)The first sealing gasket can self-recover because of the contact stress increment caused by the water in the hollow between sealing gaskets,which increases the waterproof reliability.