Abstract
In order to investigate the damage influence of the leakage explosion in urban gas pipeline on the surrounding environment, the numerical models of buried PE (polyethylene) pipes under urban pavement were established by using ANSYS/LS-DYNA in this study. The reliability of the numerical models was verified on the basis of the explosion experiments. According to the amount of gas leakage, the TNT explosive equivalent was determined. The gas leakage explosion process of buried PE pipes was studied, and the pressure and stress changes of pipes and pavements under different explosive equivalents and buried depths were analyzed; at last, the deformation law of pipes and pavements were discussed. The results show that the PE pipes are fractured during the leakage explosion and a spherical explosion cavity is formed in the soil. The pavement above the explosion point bulges upward and forms a circle. The maximum pressure of pipe near the explosion point increases linearly with the increase of explosive equivalent, and a proportional relation is observed between the fracture width of pipe and the explosive equivalent. The degree and duration of pavement deformation increase significantly with the increase of explosive equivalents. The dynamic response of the pipes is rarely affected by the buried depth, and the change of maximum effective stress is no more than 7%. However, the buried depth is of great influence on the damage degree of pavement. When the buried depth increases from 0.9 m to 1.5 m, the pavement deformation can be reduced effectively. The variation rule of pavement deformation is similar to the change rule of maximum overpressure and effective plastic stress; they change in the form of concave functions with the increase of buried depth. The results can provide theoretical basis for municipal pipeline construction design and urban safety planning and provide references for the risk assessment of gas explosion in buried pipelines.
Highlights
With the rapid development of the natural gas industry and urbanization, the laying distance of urban gas pipeline has increased greatly, the length of China’s urban natural gas pipeline increased by about 480,000 kilometers from 2009 to 2019
In order to study the mechanical response of the pipeline under external disturbance, numerical simulations and experimental researches were conducted on the deformation and dynamic response of the steel pipe or PE pipeline under deflection loads, excavation loads, or other loads [9,10,11,12,13].Explosive loading poses a greater threat to the pipeline than other external loads
At 1.2 ms and 2.1 ms, the shock waves reach the end of the pipe and the bottom of pavement, respectively. e shock waves near the explosion point continuously reflect on the free surface of the cavity outside the fracture of pipe, and the high temperature and high pressure continuously do work on the soil. e soil is compressed and deformed, forming a continuously expanding high-pressure explosion cavity that expands outward until it reaches the bottom of the pavement
Summary
With the rapid development of the natural gas industry and urbanization, the laying distance of urban gas pipeline has increased greatly, the length of China’s urban natural gas pipeline increased by about 480,000 kilometers from 2009 to 2019. Accidents often occur in buried natural gas pipelines due to external interferences, chemical corrosion, defects, or traffic loads. In order to study the mechanical response of the pipeline under external disturbance, numerical simulations and experimental researches were conducted on the deformation and dynamic response of the steel pipe or PE pipeline under deflection loads, excavation loads, or other loads [9,10,11,12,13].Explosive loading poses a greater threat to the pipeline than other external loads. Mokhtari and Nia [15] investigated the dynamic response of X65 steel pipe under underground explosive loading by numerical simulation. Compared with the pipeline thickness parameter, pipeline transportation pressure has a greater influence on the pipe
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