Impact of medium pressure gas leakage explosions on the safety resilience of underground space
HAN Yonghua1,2, HE Ding3, ZHAO Jinlong4, JI Xuewei1, WU Aizhi1, ZHOU Yi1
1. Beijing Academy of Safety Science and Technology, Beijing 101100, China; 2. Institute for Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084, China; 3. China Huanqiu Contracting & Engineering Co., LTD, Beijing 100012, China; 4. College of Emergency management and safety engineering, China University of Mining & Technology, Beijing, Beijing 100083, China
Abstract:Leakage from underground medium pressure gas pipelines can easily lead to major fires and explosions. A physical model was developed to model accidents in real underground building structures. CFD simulations were then used to predict the gas diffusion and explosion characteristics for leaks from medium pressure pipelines. The safety characteristics of the underground space were analyzed along with the impact of the accident on the resilience of the underground space. The study concluded that 2 s and 210 s are two important critical leak times for the given leakage and space characteristics. The gas concentration in a cooked food portion of a kitchen with gas leakage reached the lower explosion limit at 2 s, while the gas concentration in the hall outside the kitchen reached the lower flammability limit at 210 s. The gas explosion overpressure in the kitchen was about 12 kPa. The explosion overpressure for a 1 m thick gas layer along the top of the hallway was approximately 24 kPa. The shock wave from the kitchen explosion had little influence on the structural stability of the building, while that from the hallway explosion damaged the building structure but did not lead to complete failure of the structure. Thus, poor fire resistance in the underground space can lead to accidents and significantly impact the safety resilience. Gas explosions can affect the bearing capacity, absorption capacity and resilience of the underground space. An accident characterization curve was then developed to show the safety resilience of underground spaces with the resilience a function of the gas leakage length. The key point when the accident transitions from the formation of a dangerous condition to an explosion and deflagration is the relative location of the ignition source. More serious accidents have longer recovery times and higher costs but with better designs after the accident. The key measures to improve the spatial resilience are to promptly close the leakage source, improve ventilation to avoid the formation of a flammable cloud, control ignition sources, increase pressure relief areas, and improve space fire performance.
韩永华, 贺丁, 赵金龙, 季学伟, 吴爱枝, 周轶. 中压燃气泄漏爆炸对地下空间安全韧性影响[J]. 清华大学学报(自然科学版), 2020, 60(1): 25-31.
HAN Yonghua, HE Ding, ZHAO Jinlong, JI Xuewei, WU Aizhi, ZHOU Yi. Impact of medium pressure gas leakage explosions on the safety resilience of underground space. Journal of Tsinghua University(Science and Technology), 2020, 60(1): 25-31.
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