为解决既有隧道衬砌结构病害威胁交通安全、影响交通质量和使用寿命等问题，从工程施工、自然环境和工程地质3方面共13个独立的既有隧道衬砌结构病害影响因素入手。首先，采用层次分析法（AHP）建立既有隧道衬砌结构病害形成因素指标体系，提出基于层次-可拓（AHPExtenics）模型的既有隧道衬砌结构病害评价方法； 然后，结合工程实际和专家打分确定病害评价指标权重，进而利用相关函数对病害评价指标和权重进行可拓运算； 最后，得出既有隧道衬砌结构病害评价等级。该方法采用形式化的可拓综合评价模型替代传统的模糊综合评价法，以定量的形式给出定性分析结果，使计算结果更加客观，为既有隧道衬砌结构的病害评价提供了一种新方法。

The diseases of existing tunnel lining structure threaten the traffic safety, traffic quality and tunnel service life. Starts from 13 independent influencing factors of existing tunnel lining structure diseases from 3 aspects of engineering construction, natural environment and engineering geology, the index system of forming factors of diseases of existing tunnel lining is established by AHP method, and the diseases evaluation method for existing tunnel lining structure is proposed based on AHPExtenics mode firstly. And then, the weight of safety evaluation index is determined by combining engineering practice and expert scoring, and the safety evaluation index and weight are extended by using correlation function. Finally, the disease evaluation grade of existing tunnel lining structure is obtained. In this method, the traditional fuzzy comprehensive evaluation method is replaced by the formal extension comprehensive evaluation model, and the qualitative analysis results are given in quantitative form, which makes the calculation results more objective and provides a new method for the diseases evaluation of existing tunnel lining structure.