随着快速的城市化进程，地下管线系统越来越复杂，地下管线系统的风险显著增加。中国地下燃气管线事故数量较多，而且其事故造成的伤亡后果远远高于其他地下管线。其他地下管线在运行过程中对地下燃气管线系统造成的风险也受到燃气领域人员的关注。为了对地下管线系统进行定性、定量和系统的风险评估，综合STAMP和BN两种系统分析方法建立STAMP-BN模型，基于STAMP模型识别系统风险和因果因素，基于STAMP结果和安全控制结构，采用BN建模进行定量风险评估。应用建立的STAMP-BN模型进行地下管线系统风险评估，结果表明造成地下燃气管线泄漏的主要中间原因是三方公司的动土作业，并揭示了第三方公司和燃气公司脆弱的根本原因。可见加强第三方公司运营层协调和燃气公司协调安排、事件应急、对其他地下管线造成的慢性危害识别方面的能力是消减风险的关键。

With rapid urbanization, underground pipeline systems are becoming more and more complex, and the risks of underground pipeline systems have increased significantly. The number of underground gas pipeline accidents in China is high, and the casualty consequences of their accidents are much higher than those of other underground pipelines. Risks posed by other underground pipelines to the underground gas pipeline system during operation are focused by those in the gas industry. In order to perform a qualitative, quantitative and systematic risk assessment of underground pipeline systems, two system analysis methods, STAMP and BN, were integrated to establish a STAMP-BN model, to identify system risks and causal factors based on the STAMP model, and to perform a quantitative risk assessment using BN modeling based on STAMP results and safety control structures. The model of STAMP-BN was applied to underground pipeline risk assessment, the results show that the main intermediate cause of underground gas pipeline leakage is the earth moving operation of the third-party company, and reveal the root cause of the vulnerability of the third-party company and the gas company. It is concluded that strengthening the third-party company's operational level coordination and the gas company's ability to coordinate arrangements, incident response, and identification of chronic hazards posed to other underground pipelines is key to risk mitigation.