冻融循环冻土的冲击动态力学性能

以典型冻土为研究对象，通过不同冻融循环次数的冻融循环实验、不同温度的冻结实验以及不同应变率的冲击动态实验，综合研究了冻融循环冻土的冲击动态力学性能。结果表明，冻土存在冻融循环效应，随着冻融循环次数的增加，冻土的峰值应力有一定程度的降低，但在达到临界冻融循环次数后，峰值应力将维持稳定；同时，冻土表现出明显的应变率效应和温度效应，其峰值应力随应变率的增加或温度的降低而增加。通过定义冻融损伤因子，推导满足Weibull分布的冲击损伤，提出了一个基于Z-W-T方程的损伤黏弹性本构模型。该模型可较好地描述冻融循环后冻土的冲击动态力学行为，为研究季节性冻土区冻土的冲击动态破坏提供参考。

Impact dynamic mechanical properties of frozen soil with freeze-thaw cycles

During engineering construction and service in seasonally frozen soil regions, frozen soil is often subjected to the combined action of freeze-thaw (F-T) cycles and impact loading, which changes its physical state and mechanical properties. In order to explore the effect of F-T cycles on the impact dynamic mechanical properties of frozen soil, in this paper, the typical frozen soil was taken as the research object, and the effect of F-T cycles on the impact dynamic mechanical properties of frozen soil was comprehensively studied with the help of high and low temperature F-T cycles experimental equipment and a split Hopkinson pressure bar device, through F-T cycles experiments with different F-T cycles numbers, freezing experiments at different temperatures, and impact dynamic experiments with different strain rates. The results shows that there is an F-T cycles effect in frozen soil. With the increase of the number of F-T cycles, the peak stress of frozen soil decreases to a certain extent, but after reaching the critical number of F-T cycles, the peak stress remains stable. According to the hydrostatic pressure theory, it is believed that the F-T cycles mainly changes the mechanical properties of frozen soil by changing its microstructural characteristics. Meanwhile, the frozen soil also exhibits obvious strain rate effect and temperature effect, and its peak stress increases with the increase of strain rate or the decrease of temperature. The F-T damage factor was defined by the peak stress, and the impact damage was deduced by a statistical method that it assumes the microstructure strength of frozen soil satisfies the Weibull distribution, a damage viscoelastic constitutive model based on the Z-W-T equation was proposed. The model can better describe the impact dynamic mechanical behavior of frozen soil after F-T cycles and provide reference for the impact dynamic damage of frozen soil in seasonally frozen soil regions.