Research On Mechanical Properties Of High Water Pressure Shield Tunnel And Sealing Gasket

Shield method has become one of the mainstream underwater tunnel construction method for its good applicability,high safety,fast construction speed and easy construction quality control.The underwater shield tunnel is influenced by the water pressure effect,especially the high water pressure shield tunnel,easy to produce the phenomenon such as leakage,erosion,and affect the normal use of the tunnel and even caused serious influence on the safety.Therefore,the structural stress and waterproof problem of the high water pressure shield tunnel is a key part of the design.Take the Xiaolangdi Yellow River Diversion Project shield tunnel as the background,this article uses the shell-spring model to make structure calculation,and analyze the internal force distribution of shield lining segments in the longitudinal and horizontal view.Make an investigation of domestic and foreign joint waterproof mainstream methods.Then design the waterproof gasket section by refer to relevant engineering experience.At last,compared the sealing gasket finite element calculation results in different material hardness,section opening form and filling rate,the waterproof ability and closure pressure variation regularity of sealing gasket are deduced.The main works and research achievements include:(1)Use the shell-spring model to analyze and compare the internal force and eccentric distance along the transverse and longitudinal direction in different water pressure.It is found that with the increase of water pressure,the tube is more stable,and the internal force of the pipe section was gradually decreased along the longitudinal direction.(2)Make an investigation of sealing gasket material and joint waterproof method,Xiaolangdi Yellow River Diversion Project diversion tunnel is advised to use single-channel elastiomeric gasket,and preliminary designed six alternative sections with different opening forms.(3)Analyze the gasket calculation result in same section and different hardness,the waterproof ability and closure pressure are proportional to the material hardness,high water pressure tunnel is suitable for 65 hardness of material.And analyze the calculation result in different sections,it is found that the opening form of the triangle is better than the circular opening form in the view of stress distribution,closure pressure and waterproof ability.At last,the waterproof ability of the gasket increases with the filling rate,and the closure pressure is also improved.