Research On Property Of Steel Reinforced Spirally Wound Hdpe Drainage Pipe Joint Connected By Composite Technics Of Connection

In recent years,with the increasing demand for large-diameter polyethylene pipes in municipal engineering construction,the application of steel reinforced spirally wound HDPE drainage pipe has become more widespread.The existing specifications of the connection methods such as the clamp connection and the electric melting tape connection are all flawed,and it is possible to leave the quality defects.The research group proposed a new type of composite connection process,which combines hot melt extrusion welding and heat shrink sleeve connection,optimizing construction with complementary advantages and better joint performance while reducing costs.The composite connection process does not have the current construction work guides and acceptance criteria.The research group obtained the construction process,the performance evaluation method,and the technical and economic analysis of the connection process by conducting a series of experiments and consulting a large number of literature.Due to the lack of engineering application cases for this process,it is necessary to further study the mechanical properties and reliability of the joints using the composite construction process in order to supplement the performance evaluation methods.To solve the problems,this paper makes study on the joints performance of the composite connection process through modeling and analysis of numerical simulation and combining the overall and local pressure tests of steel reinforced spirally wound HDPE drainage pipes with two sizes.Based on the research project of steel reinforced spirally wound HDPE drainage pipe connection joint managed by Sinohydro Bureau 7 CO.,LTD.The main contents and results are as follows:(1)Two sizes of steel reinforced spirally wound HDPE drainage pipes of a screw pitch were modeled and simulated according to the experimental design.The load and deformation data were obtained.The yield force of large-size pipe was 29 kN,and the small-size pipe achieved a peak force of 7.62 kN while not obviously yield during the test.The ring stiffness of the simulated pipe was calculated by the displacement reaction force at 3% deformation,and the accuracy of the numerical simulation was determined by comparison with the standard ring stiffness.Through the post-processing module of the finite element software,the strain cloud diagram under the working condition of the pipe was obtained,which provided a reference for the experiment.(2)The DN/IN1200 steel reinforced spirally wound HDPE drainage pipes connected by the composite process was subjected to the overall compression test.Compared with the strain cloud diagram of numerical simulation,it was concluded that the maximum strain of the tubing occurred at the contact point which defined 0°,the strain decreased from 0° to 30° and then increased from 30° to 90°,the strain at the rest can be obtained from the symmetry relationship.The ring stiffness of the sample was calculated to be 8.27,which was slightly higher than the standard of the pipe SN8.It was proved that the composite connection process had a positive effect on the ring stiffness of the pipe.During the test,the pipe deformation reached 23.3%,the phenomenon of peeling and bulging did not appear upon the heat shrinkage belt,and the Hot-melt solder was not welded off,which proved the reliability of the composite connection process.(3)Through the pressure test of the DN/IN400 steel reinforced spirally wound HDPE drainage pipes connected by the composite process,the strain law of the pipe under pressure was reviewed.The average ring stiffness of the sample was calculated to be 15.20,which indicated that the smaller the diameter of the pipe,the greater the ring stiffness of the pipe was raised.The size effect was consistent with the numerical simulation results.(4)Through the local pressure test of the DN/IN400 steel reinforced spirally wound HDPE drainage pipes connected with the composite process,it was determined that the composite connection process could make the pipe and joints working in coordination.The heat shrink tape was still well wrapped under the local stress pointed at the edge of the heat shrink sleeve,demonstrating the good toughness of the heat shrinkable tape.