Explosion Coupling Risk Analysis And Assessment Of Buried Parallel Or Crossover Natural Gas Pipeline

As the construction of pipeline expands,due to the limitation of geographical and economic factors,the method of parallel laying or crossover laying closely for pipelines has been adopted widely.When one of the pipelines leaks and explodes,it is highly susceptible to damage to adjacent gas pipelines,thus a coupling effect will be created so that the severity of its consequences will be enlarged.Therefore,it is necessary to research the analysis and assessment of the explosive coupling risk of buried pipelines which are laid in parallel or crossing.For the scenario of a leak from a source pipeline under parallel and crossover conditions,where the leak explodes and impacts the target pipeline,the studies were carried out by combining theoretical studies and numerical simulations as follows:(1)Study on MISES peak stress of the target pipeline.Numerical simulation method by LS-DYNA software is used to research the MISES stress variation and MISES peak stress distribution pattern of target pipeline under the effect of gas cloud explosion from source pipeline leakage.Compared with the TNT equivalent method and TNO multi-energy method,the method is more accuracy for analyzing gas cloud explosion.The leakage model of source pipeline is improved to determine the effective explosive volume of the gas,taking into the cohesion and absorption of the soil.Modeling of predicted surface load distribution after gas cloud explosion based on numerical simulation data is established.The method for calculating MISES peak stress of target pipeline is proposed based on Boussinesq equation.The influence of design parameters and operating parameters on the MISES peak stress of target pipeline is analyzed.(2)Analysis of explosion coupling risk of buried parallel and crossover gas pipeline.For the failure probability of pipeline,the failure probability of source pipeline is analyzed by the historical statistics-corrected approach,and the failure probability of target pipeline is analyzed by the limit-state approach based on Monte-Carlo simulation.Furthermore,the joint failure probability model for parallel and crossover gas pipelines is built based on Bayesian theory.In terms of accident consequences,numerical simulation is used to analyze the shock wave superposition effect of the explosion of the two gas clouds formed by the two pipelines.Then the coupled prediction model of the accident consequences of the explosion of the two gas clouds is established.(3)Study on the method of explosion coupling risk assessment of buried parallel and crossover gas pipeline.In terms of accident probability,accident impact range,etc.,the calculation method of individual risk and social risk of pipeline explosion is improved by combining the coupled model of joint failure probability and accident consequences of parallel crossed gas pipelines.Therefore,the coupled assessment model of buried parallel crossed gas pipeline explosion risk is established.(4)Proposals for the prevention and control of explosion risk of buried parallel crossover gas pipeline and engineering application.Quantitative analysis is used to the impact of pipeline design parameters and operating parameters on the probability of pipeline accidents,and recommendations about risk prevention and control measures such as appropriately increasing the pipeline spacing and burial depth,reducing the operating pressure of pipelines appropriately are put forward.Practical cases of parallel and crossover pipelines are selected for engineering application.Then,cases are re-evaluated after the implementation of risk prevention and control measures,meanwhile the effectiveness of risk prevention and control measures is verified by comparison of pre-measures and post-measures.