Mechanical Properties Analysis Of The Bell-and-Spigot Concrete Pipeline Joints

As an important part of the urban infrastructure,the drainage pipeline play a decisive role in ensuring the normal life of the citizens.With the rapid development of China’s urbanization,the total length of drainage pipelines will continue to grow on the existing huge scale.However,due to the environmental factors,the failure accidents of drainage pipelines also occur frequently during its long life.The concrete pipe with bell-and-spigot joint is the most common structural form of the urban drainage pipeline at present,it may suffer joint failure under the coupling effects of internal fluid and overlying load,which may lead to pipe leakage.In this paper,based on the combination of field test and numerical simulation,the mechanical properties of the joints of concrete pipeline under traffic and operation loads are analyzed,which aims to provide theoretical support for the design and maintenance of concrete pipelines.The main research contents and conclusions of this paper are as follows:(1)An uniaxial tensile mechanical test of the gasket material of the concrete pipeline is carried out,and the stress-strain curves of the gasket material are obtained.Based on the test data,the material parameters of the strain energy function of the gasket are obtained by hyperelastic fitting.(2)A three-dimensional refined model of the joint of concrete pipe is established,and a full-scale test of the compressive performance of the joint of concrete pipe is carried out.The circumferential strain distribution on the inner and outer sides of joint under load is analyzed for comparison.The result shows that the numerical result is basically consistent with the experimental result that the invert and the crown on the inner side of the bell are tensile areas and the most dangerous areas.Besides,the circumferential strain on the inner and outer sides of the bell is significantly larger than that of the spigot,which is more vulnerable to damage.(3)Based on ABAQUS and Fluent finite element software,a three-dimensional refined model of the buried pipeline and the flow field model inside the pipeline are established.Through Mp CCI platform,the fluid-structure coupling numerical simulation of concrete pipeline joint under traffic and operation loads is carried out,and a full-scale test of the pipeline is carried out to verify the reliability of the established fluid-structure coupling numerical model.The result shows that the influence of working conditions on the circumferential stress of the pipe joint are mainly concentrated on the crown and the invert of the joint,the areas vulnerable to tensile damage.The change of flow field leads to the slight difference in the vertical deformation of the joint,while variation in gasket hardness and cushion compactness have certain influence on the vertical deformation of the joint.The change of buried depth has a negative correlation to the vertical deformation of joint,and the change of load position has a significant nonlinear effect.