Research On Third Party Excavation Construction Damage Risk Assessment Technology For Urban Gas PE Pipeline

With the increasing demand for clean energy such as natural gas,the gas industry in China has entered a period of vigorous development,and the construction of urban gas pipeline network is also accelerated.Because of the excellent properties of polyethylene(hereinafter referred to as PE),PE has been widely used.However,with the accelerated pace of urban expansion,third-party excavation construction causes the gas PE pipe leakage accident occurred frequently.Therefore,it is necessary to improve the degree of attention to the excavation construction damage of gas PE pipeline.In order to solve the problem of the relative lack of PE pipe evaluation and enrich the risk assessment of urban gas pipeline.The main research contents are as follows:Analysing piping loads combined with PE pipeline mechanical characteristics,and establishing the mechanics model.The mechanical damage mechanism of PE pipe was studied,and the reason of pipeline failure was analyzed from the view of microstructure.According to the mechanical characteristics of PE pipe,the failure criterion under excavation load was established.According to the engineering practice,ABAQUS software was used to build models.The simulation got on two aspects,such as bucket teeth were directly applied to the pipeline and not directly acting on the pipeline.Dynamic response,mechanical characteristics and the influence of various parameters on the pipe force were analyzed.Introducing Vulnerability Theory to calculate the failure probability of pipe.Risk factor system is established based on the "4M" system,and some computing methods were used to calculate probability of danger.The vulnerability probability was determined according to the simulation results and the PE pipe characteristics.The failure probability of the pipeline was obtained combining the probability of danger and the probability of vulnerability.Researching on pipeline leakage model and gas diffusion model,and determining the empirical probabilities and calculation models for the occurrence of various types of accident consequences.And according to the destruction criteria to determine the consequences which includes the accident area,the number of deaths and economic losses.The principle of ALARP was introduced and the risk matrix was used to classify the failure probability and the failure consequence,so to determine the risk grade of PE pipeline excavation damage.Using the risk evaluation model established in this paper to evaluate the actual case,the result were consistent with the actual situation.So the research results of this paper can provide some technical support for the risk assessment technology and integrity management of urban gas pipeline.