Failure Mechanism Of Socket Ductile Iron Water Supply Pipeline Joint Under Vertical Load

When the urban water supply pipeline joint encounters external loads such as foundation settlement and traffic load,accidents such as leakage and pipe bursting of the pipeline joint often occur,resulting in huge economic losses and bad social impacts.One of the deep-seated reasons for the frequent occurrence of pipe bursts and leaks in the water supply network is that the mechanical characteristics and damage mechanisms of urban buried water supply pipelines under external loads are still unclear,and systematic research is urgently needed.In view of this,this paper takes the socket-type ductile iron water supply pipeline joint as the research object.Based on the existence of large voids(with soil)and the situation with good backfill support(without soil)under the pipeline joint,experimental research and numerical analysis are used,to carry out research on the failure mechanism of socket-type ductile iron water supply pipeline joint under vertical load.Provide basic research and technical support for the control of leakage rate of socket-type ductile iron water supply pipes.The main research work and results of this paper are as follows:(1)An experimental study on the leakage and failure mechanism of DN100 ductile iron socket and socket pipe joints under vertical load in the case of no soil was carried out.Considering that there is a large cavity below the pipeline joint,it is a case of no soil,and it is simplified to a simply supported beam model.The vertical displacement,relative rotation angle,and axial and hoop stress-strain distribution of the pipeline joint under different vertical loads are studied.law,and the deformation characteristics of the rubber sealing ring.The main reason for water leakage in the pipeline is that the relative rotation between the bearing tube and the intubation tube is too large,and the rubber sealing ring on the top of the tube is pulled out of the sealing groove under the action of friction,resulting in water leakage in the pipeline.In addition,the relative rotation angle of the initial leakage of the DN100 socket-type ductile iron pipe joint in the case of no soil was obtained.(2)An experimental study on the leakage and failure mechanism of DN100 ductile iron socket and socket pipe joints under vertical load in the presence of soil was carried out.Considering that there is good backfill support under the pipeline,it is simplified as a spring support model,and the vertical displacement,relative rotation angle response,and axial and hoop stress-strain distribution of the pipeline joint under different vertical loads are studied,and the deformation characteristics of the rubber ring.The main reason for water leakage in the pipeline is that the rubber sealing ring at the bottom of the pipe is damaged by excessive extrusion when the cannula is pulled out,and finally the sealing at the bottom of the rubber ring fails,resulting in water leakage in the pipeline.In addition,the relative rotation angle of the initial leakage of the DN100 socket-type ductile iron pipe joint in the presence of soil was obtained.(3)Research on the failure mechanism of socket-type ductile iron water supply pipe joints under vertical load is carried out.Based on the test,a reliable finite element model was established to reflect the failure mechanism of the socket-type ductile iron water supply pipeline joint,and the sensitivity analysis of different wall thicknesses,different pipe diameters,and different soil stiffness parameters was carried out.The initial leakage index of the DN100socket-type ductile iron pipe joint was determined;the leakage and damage mechanism of the ductile iron water supply pipe joint was revealed.