The Analysis For Safe Distance Of Buried Parallel Pipeline Based On The Leakage Explosion

With the development of the society,the long pipeline laying area is limited by the complex terrain and traffic,environmental constraints and other reasons.In the other hands,the increase of natural gas consumer,gas consumption and the reasons of pipeline operators for their own development result in serious shortage of pipeline mileage.The single buried pipeline has been unable to meet the demand of natural gas long distance transport.The parallel pipeline has become an important mode of pipeline transport system and has put forward higher requirements to the enterprise.It is a key for the pipeline operation enterprise to determine the safe distance of parallel pipeline operation improve the operation and management level.The reasons for the leakage of buried pipeline has been illustrated by MATLAB based on the study of buried pipeline leakage combined with fluid mechanics,explosion shock theory and vapor cloud explosion.The law of natural gas diffusion concentration in soil with time and the TNT equivalent values of buried pipeline leakage and explosion have been obtained.Analyze the leakage and explosion effect on the different areas class pipeline.The quantity of TNT explosion is determined and the validity of TNT equivalent method is verified.The mathematic model of buried parallel pipelines has been established and numerical analysis has been processed by AUTODYN.According to the analysis result,the parallel security distance is determined.The results show that the natural gas explosion effect on the buried parallel pipeline can be divided into three levels with the parallel distance increase: large deformation,continuous slight deformation,no damage effect.The parallel safety distance is divided according to the pipeline failure forms,which is bounded by different parallel distance when buried parallel pipeline exploded.Pipeline deformation caused by explosion overpressure damage and soil compressive deformation when parallel distance is less than 3m.Overpressure damage plays a main role at early stage and soil compressive deformation at late stage.Fracture failures generate.Pipeline deformation mainly caused by soil compressive deformation when parallel distance is between 4m with 6m and fracture failures in pipeline.Deformation stress is mainly derived from the soil visco-elasticity deformation stress and no fracture failures appear when parallel distance is more than 6m.But pipeline still produces large deformation when parallel distance is less than 8m.Accidents interaction will not occur when parallel distance is more than 8m.Otherwise,parallel pipeline failure will occur affected by adjacent pipeline explosion.The probability of adjacent pipeline failure is the probability interaction of parallel pipeline accidents with this distance.The minimum safety distance of buried parallel pipeline is more than 8m.