针对地铁项目施工环境复杂、不可预见因素多、施工事故频发、难以对其进行快速有效的应急决策与救援的问题，首先，搜集以往地铁施工应急案例，分析地铁施工风险因素，运用Protégé软件建立知识本体模型；然后，计算本体库中源案例与目标案例的综合相似度，从案例库中匹配出综合相似度最大的源案例，通过对比本体库中与目标案例相似度最高源案例的关键属性，运用规则推理对相似案例的应急措施进行适用性修改，从而提高应急措施的针对性，为快速有效地应对地铁施工事故进行应急决策提供新的方法；最后，以某地铁项目施工为例，验证了该相似度算法的合理性。

The construction environment of metro project is complex; the unforeseeable factors are many; the construction accidents are frequent, and it is difficult to carry out quick and effective emergency decisionmaking and rescue. Firstly, the emergency cases of metro construction are collected; the risk factors are analyzed; and the knowledge ontology model is established by software Protégé. And then the comprehensive similarity between the source case and the target case in the ontology library is calculated; the source case with maximum similarity degree is selected, the key properties of source case in ontology library and target case are compared; and the adaptability of emergency method of similar cases are modified by rule reasoning to improve the pertinence of the emergency method and provide a new method for emergency decisionmaking and rescue of metro accidents. Finally, the rationality of the comprehensive similarity algorithm is verified by a case stady.