对天然气长输管道的风险分析大多忽视了减缓性安全措施对事故后果的削减作 用． 文中提出一种将防爆墙降低事故后果严重度的效果量化地计入天然气长输管道定量 风险分析中的方法． 首先定义防爆墙对天然气长输管道爆炸冲击波超压的削减率及计算 公式，并利用能量等效原理修正事故参数值，最后分析管道周边敏感目标区域在建立防爆 墙后承受风险水平的降低程度． 案例分析表明: 修建防爆墙后，脆弱目标区域内冲击波超 压的平均削减率约为50． 05%;个人风险、社会风险水平均降低至可以接受水平． 建立的 安全措施在定量风险评价中的量化表征方法，可以为保障天然气长输管道周边敏感场所 的安全设施建设提供技术参考． 

The control function of safety-prevention measures and the effect of mitigating safety measures on reduction of accident consequences are seldom considered in the analysis assessment of a general long-distance natural gas pipeline risk． A method that can quantify the effect of the explosion proof wall in quantitative risk analysis of a long-distance natural gas pipeline is proposed． Firstly，the attenuation rate calculation formula of the explosion proof wall resisting explosion shock wave overpressure of a long-distance natural gas pipeline is defined，and then the method to solve the attenuation of shock wave overpressure in a sensitive target area after the explosion proof wall is used． Finally，through correcting the accident parameter value based on the energy equivalent principle， an analysis is performed of the risk reduction level of a sensitive target area surrounding pipeline after the explosion proof wall was constructed． The case study suggests that the average rate of reduction of shock wave overpressure in sensitive target area after the explosion proof wall about 50. 05% was constructed; the individual and the social risk is reduced to an acceptable level． The quantitative characterization method of safety measures in quantitative risk assessment can provide technical reference for the construction of safety facilities in the surrounding area of a longdistance natural gas pipeline．