| The shield tunnel support structure consists of assembled segments.Waterproofing of segment joints is achieved by using rubber gaskets nested in prefabricated grooves.At present,there are few studies on the waterproof joints of shield tunnel segments,and the waterproof design of shield joints is still based on empirical design and testing.Based on the study of the research results of the predecessors,this paper explores the four aspects of the numerical simulation method of the gasket,the design parameters of the elastic gasket,the influence of the tube assembly on the gasket and the waterproof failure mode of the gasket.The specific research contents are as follows:(1)The numerical simulation methods of shield tunnel gaskets are studied,including the selection of numerical simulation software for gaskets,the selection of constitutive model for rubber materials,and the method of deriving C01 and C10 parameters from rubber hardness.The contact relationship involved in numerical simulation of gasket compression is analyzed,and the contact types are classified.Qualitative and quantitative methods were used to study the meshing method of model,and the evaluation index and method of numerical simulation of gasket were discussed.Secondly,based on the change of the opening ratio,the influence of the size change of the closed hole and the open hole on the waterproofing performance of the gasket is analyzed.(2)The data of shield tunnel gaskets in existing projects in China are investigated,and the data of gaskets material and section form are statistically analyzed.Based on the data of the outer wheel of the gasket,the design parameters of the outer contour of the gasket were studied by linear regression method.Based on the investigation results,the influence of the arrangement of closed holes and the shape of closed holes on the waterproof performance of the gasket was studied.Finally,the influence of rubber material parameters on waterproofing performance of sealing gasket is studied from the angle of rubber hardness.(3)The non-standard assembling forms of segment assembling which may lead to waterproofing failure of sealing gaskets in construction stage are studied,and the causes are qualitatively analyzed.Aiming at the difficulty of measuring the rotation angle of segment joints in assembling stage,a method for calculating ellipticity and rotation angle of segment joints in assembling stage is established.The relationship between the ellipticity of segment assembling and the rotation angle of segment joints is analyzed based on specific projects,and the influence of the position of key block on the rotation angle of segment joints is analyzed from the angle of waterproofing.According to the non-standard assembling form,the influence of different assembling states on the compression characteristics of gaskets was studied.(4)The leakage situation of shield tunnels under construction is investigated and the macroscopic form of leakage of shield tunnels is obtained.Based on specific projects,the failure modes of waterproofing of shield tunnel sealing gaskets when segment joints are opened or staggered are quantitatively analyzed.The numerical model of rotational waterproofing performance of segment joints was improved,and the failure modes of seal gasket waterproofing under negative rotation and positive rotation of joints were studied.The methods to improve the waterproofing ability of sealing gaskets were explored from three aspects:geometric adjustment,rubber hardness adjustment and combination of the two. |
PDF Full Text Request