Mechanical Response Analysis Of Defective Buried Natural Gas Pipelines Under Shock Loads

As a green,low-carbon and clean energy,natural gas plays an important role in promoting China's economic and social developments and adjusting China's energy structures.And natural gas pipelines play a key role in energy transportation and are known as the “energy lifeline”.Due to the characteristics of large diameter and thin wall of natural gas long-distance pipelines,the pipelines failure occur under the impact load of collapsed rocks in the geological disasters in the mountainous areas.At the same time,with the increase in the service life of natural gas pipelines,explosion accidents caused by failure and leakage of natural gas pipelines due to corrosion defects continue to occur,and safety problems are becoming more and more serious.Therefore,in order to ensure the safe and stable operation of long-distance natural gas pipelines,we have established a limit state equation by analyzing and discussing the law of influence of natural gas pipelines under the impact load of rockfalls,and proposed targeted suggestions and countermeasures for the treatment of natural disasters of rockfalls and pipeline protections,which to make predictions and prevention and control measures in advance are of far-reaching significance to ensure the safe and stable operation of China's long-distance natural gas pipelines.The research mainly includes the following aspects:(1)Establish finite element models of non-defective natural gas pipelines and rockfalls.According to the volumes and velocities of the rockfalls,the buried depth,diameter,internal pressure and wall thickness of the pipelines have an effect on the mechanical responses of the shallow buried,exposed and suspended pipelines under the impact load of the rockfalls.(2)Establish finite element models of natural gas pipelines with corrosion defects and rockfalls.According to the impact of the length,depth,and width of corrosion defects have an effect on the mechanical responses of the shallow buried,exposed,and suspended pipelines under the impact load of rockfalls.(3)Through the finite element numerical simulation of the above two models,the change trend of the natural gas pipelines stress curve is obtained.And determine the most important factor that affects the pipeline stress change after carrying out to the comparative analyses.(4)Perform multiple linear regression analysis through SPSS software.Use the most important factor affecting pipeline stress changes as dependent variables to perform regression analysis and integration,so as to obtain the stress limit state equations for natural gas pipelines with corrosion defects under the impacts load of rockfalls.