Double Steel Shell Concrete Immersed Tunnel Research On Pipe Joint Performance

With the development of coastal urban agglomerations,the increasingly close communication between cities has made the demand for underwater tunnel engineering more and more.The immersed tube method is the most prominent one in the underwater tunnel construction method,and its engineering application has been rapidly developed.For the design requirements of long span,deep water pressure and long life,the concrete immersed tunnel is not suitable for the conditions,so the double steel shell concrete immersed tunnel becomes the best choice.As the key part of the design,the joints of the pipe joints will pose a great threat to the GINA water stop and shear keys under different working conditions.Therefore,it is of great practical value to study the joint performance of double-layer steel shell concrete immersed tunnel joints.This paper takes the Shenzhen-Zhongshan cross-river immersed tunnel project as the engineering background,consults the relevant literature,combines the theoretical analysis and uses the ABAQUS finite element software to establish a double-layer steel shell concrete pipe joint and pipe joint model,and studied GINA.The waterproof ability of the water stop,the shearing performance of the horizontal concrete shear bond and the force deformation of the vertical steel shear bond under the uneven settlement.Through research,the following conclusions are drawn:(1)The initial compression of the GINA waterstop is a design requirement that is met after hydraulic crimping,but the limit of the reduction in compression during the operational phase is the minimum compression.The calculated values of the initial compression and the minimum compression are different under different water depth conditions.The bottom of the GINA waterstop is a water-resistant area that is waterproof and depends on the contact stress at the bottom.(2)During the shear load loading process,the shear force bond is plastically strained at the tight corner of the meshing joint,and the non-loading side shear bond damage of the meshing is more serious.The yield bearing capacity of the joint is 32 MN,and the maximum shear capacity is 72 MN.The damage path develops in the horizontal direction and has a linear and progressive relationship within a certain range.(3)In the different working conditions caused by uneven settlement of foundation,the stress value and variation trend of vertical steel shear bond of pipe joint are relatively obvious.In the longitudinal downward bending condition,the tensile and compressive stress of the side wall shearing force are larger than the middle wall shearing key,and the side wall shearing key has obvious effect on resisting the bending moment;in the vertical upward bending condition,the middle wall shearing key resists the longitudinal direction.The importance of bending is greater than that of the side wall;in the longitudinal torsion condition,the shear force of the middle wall is evenly applied,and the side of the side wall is not bent.(4)Through the analysis of the displacement of the vertical shearing keys of the upper,middle and lower parts after meshing,the amount of shear bond deformation generated under each working condition under specific water depth conditions is determined.In the longitudinal downward bending condition,the shearing force of the side wall is the largest,which is 1.8mm;in the longitudinal upward bending condition,the shearing key in the middle of the side wall has the largest deformation,which is 1.63mm;in the longitudinal torsion condition,the side wall is set to one side.The upper shear button has the largest deformation amount of 2.1 mm.