季节冻土区高速铁路防冻胀路基保温强化特性研究

季节冻土区路基的冻胀变形影响高速列车的运行速度、行车安全。以普通级配碎石路基结构为原型，建立轨下基础热-力耦合模型和路基结构外力作用模型，通过温度场和变形场的现场监测数据、力学特性计算的文献资料验证了模型的可靠性。在此基础上建立水泥稳定碎石路基、保温强化层+级配碎石路基、保温强化层+水泥稳定碎石路基3种防冻胀路基模型，计算冻胀变形和受力特性。结果表明：保温强化层和水泥稳定碎石填料均有效减小了路基的冻胀变形，其中保温强化层+水泥稳定碎石路基的冻结深度和最大冻胀量最小，分别为0.8 m、1.585 mm；保温强化层可减小基床表层竖向应力，且弹性模量较大的水泥稳定碎石可加速竖向应力的衰减，使得基床底层承受应力减小。保温强化层+水泥稳定碎石基床表层结构可为季节冻土区高速铁路路基结构的选型提供参考。

Thermal insulation and strengthening properties of anti-frost heaving subgrade structure of the high-speed railway in seasonally frozen soil region

Frost heaving deformation of the subgrade in the seasonally frozen region affects the running speed and safety of high-speed trains. Taking ordinary-graded macadam subgrade structure as the prototype, we established the thermal-mechanical coupling model of subgrade foundation and the external force model of subgrade whole structure. Then the temperature field, deformation field and structural mechanical parameters were calculated and compared with literature data, which further verified the reliability of the model. On this basis, three anti-frost heave structural models were established, including the cement stabilized gravel subgrade, thermal insulation strengthening layer with graded macadam subgrade, and thermal insulation strengthening layer with cement stabilized macadam subgrade. Finally, the frost heave deformation and stress characteristics were calculated. The results show that the thermal insulation strengthening layer and cement stabilized macadam filler can effectively reduce the frost heaving deformation of the subgrade. The frost depth and maximum frost heaving of the thermal insulation strengthening layer with cement stabilized macadam structure are the smallest, which are 0.8 m and 1.585 mm. Moreover, the thermal insulation strengthening layer can reduce the vertical stress of the surface layer of the subgrade, and the cement stabilized macadam with larger elastic modulus can accelerate the attenuation of vertical stress and reduce the stress of bottom layer of subgrade. The thermal insulation strengthening layer with cement stabilized macadam subgrade surface structure can provide references for the selection of high-speed railway subgrade structure in the seasonal frozen zone.