Cold Tide Resistance Function Reliability Analysis Of Municipal Water Supply Networks

In recent years,water supply pipe network burst accidents caused by cold wave emerge one after another,which seriously affect people’s normal life and orderly urban operation.But the current study of cold resistance of reliability analysis of water supply pipe is small,especially on reliability of water supply system function,is almost a blank.This paper mainly studies the functional reliability of cold tide resistance of water supply networks,as follows:(1)To carry out during the cold city buried water supply pipeline reliability analysis,starting from the soil around pipeline temperature,stress analysis was carried out on the cold wave during pipeline,and give the temperature difference stress affected by the temperature during the cold wave by considering the relationship among temperature,soil medium and pipeline.Assuming that the failure mode of the pipeline section during the cold wave is joint failure,The formula of pipe deformation and three working states of pipe joint failure are given,and the method of calculating the reliability of water supply pipeline against cold wave is put forward,and the deformation reliability of water supply pipeline joint is calculated;Based on the research of reliability of cold wave resistance of water supply pipeline,the function of cold wave resistance of water supply networks is analyzed.From the point of view of pipe joint with leakage,this paper analyzes the four stages of pipe joint leakage and the formula of leakage area corresponding to each stage,arranges the joint leakage in the water supply network,and calculates the node water pressure of network under the leakage state by combining the hydraulic analysis software EPANET.Based on the improved first-order second-order moment method,the function with node water pressure as variable is established,and a calculation method of functional reliability of water supply networks against cold wave is proposed.The results show that the improved first-order second-order moment method is suitable for the reliability calculation of cold tide resistance of water supply networks.(2)The reliability calculation method of cold tide resistance of water supply networks is applied to the engineering example,and the reliability analysis with practical engineering significance is realized.The cold tide resistance reliability of water supply pipeline and network in Suzhou industrial park was calculated respectively,and the reliability status of pipes and joints in the network was evaluated according to the reliability probability The results show that: in the analysis of pipeline reliability,the joints of ball milled cast iron pipeline are basically in good condition in different degrees of cold wave,while the joints of gray cast iron pipeline are mostly in slight leakage state;in the analysis of the function of water supply pipe network joints,the joints of water supply pipe network with ball milled cast iron pipe are in safe state in different degrees of cold wave,while the joints of water supply pipe network with gray cast iron pipe are in safe state in different degrees of cold wave The results of reliability calculation of different pipe joints show that the ball milled cast iron pipe body and gray cast iron pipe joints are more vulnerable to the impact of cold wave and have potential safety hazards.This study provides a basis for cold wave early warning of water supply network.