为分析隧道衬砌结构服役期破坏演化特征，为后续采取监测应对措施提供参考，针对运营期公路隧道常见软弱围岩、浅埋偏压2种情况，分别建立计算模型。采用强度折减法，不断折减围岩的强度参数，研究结构折减系数与结构状态的相互关系，并通过衬砌结构的极限应变分布规律研究结构安全状态，提取不同状态的典型结构力学特性指标，对运营期公路隧道结构失稳破坏模式进行分析。总结得出，在软弱围岩（非偏压）条件下，隧道衬砌结构的边墙下部、仰拱中部及拱顶更易变形、开裂甚至破坏，边墙和拱顶较仰拱更早出现变形、开裂，监测应重点针对衬砌结构初始变形开始至边墙出现活动铰这个阶段，以防止边墙出现活动铰而导致进一步仰拱破坏。在浅埋偏压条件下，隧道衬砌结构的两侧拱腰及拱脚，是监测的关键部位，破坏呈拱脚先于拱腰、临空侧先与临土侧的特点，衬砌结构初始变形开始至临空侧拱脚及拱腰破坏这个阶段，是监测关注的重要阶段，同时应以防止临空侧发生破坏为主要目标。

In order to analyze the failure evolution characteristics of tunnel lining structure during service period and provide reference for subsequent monitoring and response measures, calculation models for the two common cases of weak surrounding rock and shallow buried bias pressure at the portal of highway tunnel during operation are established. The relationship between the structural reduction coefficient and the structural state is studied using strength reduction method to continuously reduces the strength parameters of surrounding rock. Through the limit strain distribution law of lining structure, the structural safety state is studied, the typical structural mechanical characteristic indexes in different states are extracted, and the instability and failure modes of highway tunnel structure during operation are analyzed. It is concluded that under the condition of soft surrounding rock (non bias pressure), the lower part of sidewall, the middle part of inverted arch, and arch crown of tunnel lining structure are prone to deformation, cracking, and even damage, and the deformation and cracking of sidewall and arch crown occurs earlier than that of inverted arch. The monitoring should focus on the stage from the initial deformation of lining structure to the movable hinge of sidewall,  so as to prevent the sidewall from further invert damage due to movable hinge. Under the condition of shallow buried bias pressure at the portal, the arch waist and arch foot on both sides of the tunnel lining structure are the key parts of monitoring. The damage first occurs to the arch foot ahead of the arch waist, the free side, and the soil side. The stage from the initial deformation of the lining structure to the damage of the arch foot and arch waist on the free side is an important stage for monitoring hence the free side, should be prevented from damage.