寒区隧道衬砌背后空洞中的积水在低温条件下冻结会产生局部冻胀力。假设隧道衬砌背后空洞为半椭圆形空间，将冻胀过程中围岩-冰体-衬砌间的相互作用简化为串联弹簧，推导半椭圆形积水空间局部冻胀力解析解，建立三维数值模型验证了该解析解的有效性。进一步研究局部积水冻胀力和围岩级别、衬砌刚度、积水深度、冻胀率的关系，分析冻胀位置对衬砌结构力学特征的影响。结果表明：寒区隧道局部积水冻胀力与围岩级别负相关，与衬砌刚性、积水深度、冻胀率均正相关。各因素对冻胀力的影响程度为：积水深度>衬砌刚度>围岩级别>冻胀率。积水冻胀对衬砌结构的影响主要发生在冰体和衬砌接触区域，导致隧道向内侧收敛变形。当积水空间位于仰拱处时衬砌主应力最大，位于拱脚处时衬砌主应力最小。在局部冻胀作用下衬砌结构弯矩和轴力出现突变，表现为临空侧受拉区衬砌的弯矩增大、轴力减小，围岩侧受拉区衬砌的弯矩减小，轴力减小。衬砌不同部位的刚度差异导致冻胀力对结构安全产生不同的影响。冻胀位置对结构安全影响程度为：拱顶>仰拱>拱肩>拱脚>墙脚。

The accumulated water in the cavity behind the tunnel lining in cold regions may freeze under low-temperature conditions, resulting in local frost heave pressure. Assuming that the cavity behind the tunnel lining was a semi-elliptical space, the interaction between the surrounding rock, ice body, and lining during the frost heave process was simplified as springs in series, and an analytical solution for the local frost heave pressure in the semi-elliptical water-accumulated space was proposed. A three-dimensional numerical model was developed to verify the effectiveness of the analytical solution. Further, the relationships between local water-accumulated frost heave pressure and surrounding rock grade, lining stiffness, water-accumulated depth, and frost heave level were studied, and the influences of frost heave position on the mechanical characteristics of lining structure were analyzed. The results show that the local water-accumulated frost heave pressure of the cold region tunnel is negatively correlated with the surrounding rock grade and positively correlated with the lining stiffness, water-accumulated depth, and frost heave level. The influence degree of various factors on frost heave pressure is as follows: water-accumulated depth > lining stiffness > surrounding rock grade > frost heave level. The impact of water-accumulated frost heave on the lining structure mainly occurs in the contact area between the ice body and the lining, leading to the convergence of the tunnel towards the inner side. The principal stress of the lining is maximum when the water-accumulated space is located at the inverted arch, and the principal stress of the lining is minimum when it is located at the arch foot. Under the action of local frost heave, there is a sudden change in the bending moment and axial force of the lining structure, manifested as the bending moment increase and axial force decrease of the lining under tension on the air side, as well as the bending moment decrease and axial force decrease of the lining under tension on the surrounding rock side. The stiffness differences in different zones of the lining lead to different impacts of frost heave pressure on structure safety. The influence degree of frost heave position on structure safety is as follows: vault > inverted arch > arch shoulder > arch foot > wall foot.