寒区隧道衬背局部积水冻胀对衬砌力学性能影响的数值模拟研究

Numerical Simulation of the Mechanical Effects of Localized Frost Heave behind Linings in Cold-Region Tunnels

摘要: 针对寒区偏压浅埋隧道衬背局部积水诱发的非对称冻胀病害，本文依托索同坡隧道开展了热–力顺序耦合数值模拟。研究引入二维Cohesive单元等效表征局部积水区，提出随温度动态衰减的正则化热膨胀系数以精细刻画水–冰相变膨胀行为，系统对比了10次冻融循环下无积水、拱顶及边墙积水的力学演化规律。结果表明：局部冻胀对衬砌具有显著的“非对称杠杆破坏效应”；边墙积水对结构的劣化威胁远超拱顶，其单侧膨胀不仅致使积水侧横向鼓出变形，更诱发结构整体偏移，导致对侧及拱顶产生高达1.62 MPa的拉应力集中。多次循环加载下，衬砌残余变形与拉应力峰值呈“先累加、后稳定”的演化特征，但高幅值周期性偏压仍使边墙面临长期疲劳损伤风险。研究成果可为类似隧道的局部防排水与抗冻设计提供理论依据。

Abstract: Asymmetric frost heave caused by localized water accumulation behind tunnel linings is a critical issue for shallow-buried, unsymmetrically loaded tunnels in cold regions. To investigate this, sequential thermo-mechanical coupled simulations were conducted using the Suotongpo Tunnel as a case study. A 2D cohesive element was introduced to equivalently model the localized water accumulation zone. Additionally, a temperature-dependent regularized thermal expansion coefficient was proposed to accurately capture the volumetric expansion during the water-ice phase transition. The structural responses over 10 freeze-thaw cycles were systematically evaluated under three conditions: no water accumulation, vault accumulation, and sidewall accumulation. Results indicate that localized frost heave exerts a pronounced “asymmetric leverage failure effect” on the tunnel lining. Specifically, water accumulation at the sidewall poses a significantly greater threat of structural degradation than at the vault. Unilateral expansion at the sidewall not only causes lateral bulging on the affected side but also drives overall structural deflection, resulting in tensile stress concentrations of up to 1.62 MPa on the contralateral side and vault. Over multiple freeze-thaw cycles, the residual deformation and peak tensile stresses initially accumulate before reaching a stabilized state. Nevertheless, the high-amplitude periodic unsymmetrical loading still exposes the sidewall to long-term fatigue risks. These findings offer a theoretical reference for targeted waterproofing, drainage, and frost-resistance designs in similar tunnels.