Study On Safety Evaluation Technology Of Gas Pipeline Buried In Geological Crossing Fault

In recent years,China's demand for natural gas has been increasing rapidly.Construction objects such as "West-to-East Gas Transmission Project" and "China-Myanmar Pipeline" are the vertex.Because of the complicated terrain in China,inevitably,long-distance gas transmission pipelines will cross active fault areas.Resulting from the effect of fault displacement,cross-fault buried gas pipelines will be squeezed and even be damaged,which would result in a huge economy loss and environmental damage.However,the current domestic and international research on cross-fault buried gas pipelines mainly based on analytical methods and numerical simulations,there are few studies on safety assessment methods for cross-fault buried gas pipelines.Therefore,it is necessary to study the safety assessment methods for cross-fault buried gas pipelines.Firstly,this paper studied the failure mechanism and theoretical analysis method of cross-faulted buried gas pipelines,created a finite element analysis model of cross-fault buried gas pipelines,and validates the cross-faults model established in this paper by using The Seismic Technical Specifications of Oil and Gas Pipeline Engineering.The advantages and disadvantages of stress-based failure criteria and strain-based failure criteria are compared.Combined with the authentic conditions of cross-fault buried gas pipelines,this paper selected a strain-based failure assessment as the standard.Secondly,based on the finite element model of cross-faulted gas transmission pipelines established in this paper,and various factors,such as the types of faults,the fault displacement,the intersection angle between the pipeline and the fault,the pipe inclination,the wall thickness of the pipeline,the outer diameter of the pipeline,the internal pressure of the pipeline,the depth of the soil and the soil depth of the pipeline,and the soil properties,are considered.There are 9 factors including body parameters are used to analyze the stress-strain response of each factor under different fault dislocations,and the key factors affecting the safety of cross-fault buried gas pipelines were identified,and the rating of these influencing factors was ranked.Based on the theory of vulnerability,combining the results of numerical simulation of cross-fault buried gas transmission pipelines,a safety evaluation index system for cross-fault buried gas pipelines was established.The safety evaluation index system contains three aspects:the vulnerability of hazard factors,the hazard bearing body and vulnerability of accident response capabilities.The entropy weight method was used to determine the weight values of each vulnerability index,and the safety grades of cross-fault buried gas transmission pipelines were determined by the collection method.Finally,the safety assessment of cross-faulted gas pipeline is practiced in a certain segment of the China-Myanmar pipeline,which has determined its safety level and corresponding safety measures are proposed.