Investigation On Compression And Waterproof Behaviour Of Segment Gaskets Of Shield Tunnels Under High Water Pressure

With the construction of major projects such as cross-sea tunnels,higher requirements are placed on the waterproof design of shield tunnels under complex environmental conditions.The high water pressure environment will have non-negligible effects on the waterproof performance of the tunnel segment gasket.Based on the KVMRT Line 2Project in Kuala Lumpur,Malaysia,this paper studied the compression and the influencing factors of the waterproof performance of the shield tunnel segment gaskets,theoretical analysis,experimental investigation and numerical simulation were conducted on this paper.This study tested and analyzed the expansion ratio performance of two kinds of expanded materials,analyzed the data of the compression deformation test of the three different cross-section gaskets,simulated the compression deformation process of rubber gaskets by finite element method and proposed optimization design method."T" seam waterproof test was also carried out,the water pressure was simulated by finite element software to obtain the contact pressure of the gasket,the relationship between contact pressure and maximum water pressure under different dislocation and opening was investigated.Major conclusions of this study are as follow:1)The expansion law of two water swellable materials are revealed.The product-type water-swellable rubber with high water-absorbent resin as the main effective expansion properties has lower expansion stability than water-swellable polyurethane,the volume expansion ratio of product-type water-swellable rubber gradually decreased after immersion for 25 days.While,the expansion ratio of the water-swellable polyurethane elastomer dipped in pure water and 3% brine had no obvious change,that is mean the expansion properties of water-swellable polyurethane are not affected by the ion concentration.2)Determined the effect of cross-sectional holes shape and openings ratio on the compression deformation performance of the gasket.Under the condition that the holds rate is almost the same,when the tunnel segments are completely closed,the triangular holes are not completely closed,the slope deformation occurs at the bottom columnar part,and the large deformation is occur at top edge.While the circular hole almost closed completely,the column parts at the bottom of the seal were not slope,the overall deformation of the section is uniform.Under the condition of the same hole type and different opening rates,the higher the opening rate is,the better the compressive elastic properties of the gaskets will be,and the better the construction will be.3)Established the relationship between the maximum water pressure resistance of the gasket and the contact pressure.Due to the errors in actual construction,the amount of opening and dislocation between pipe segments will reduce the contact surface pressure and waterproof performance of gasket.The larger the amount of dislocation,the greater the compression contact pressure required to achieve the design of waterproof water pressure gasket,Therefore,it is necessary to reduce the errors of segment joint assembly in tunnel construction.