中文摘要：

冻土的强度及变形行为受加载速率及环境温度效应的影响。以冻结兰州黄土为对象,开展了一系列不同温度及加载速率下的常规单轴压缩、变速率压缩及加卸载蠕变回弹试验。基于常规单轴压缩试验结果,考虑了加载速率对变形行为的影响;通过变速率压缩试验,引入了一个与加载速率相关的率敏感性系数,构建一个新的考虑率效应的冻土强度关系式,解决了由试样离散性而对率效应试验研究带来的不利影响;运用加卸载蠕变回弹试验实现了对冻土变形中弹性、塑性变形的解耦,并获得了率无关弹性模量。以此为基础,在一定的温度、加载速率范围内建立了考虑率效应及温度效应的冻结黄土单轴唯像本构模型。通过试验验证,该模型能较好地模拟冻结黄土在不同温度和不同加载速率条件下的应力应变行为。

英文摘要：

The loading rate and temperature have great influences on the strength and deformation behaviors of frozen soil. A series of mechanical tests on frozen loess, including constant-strain-rate uniaxial tests, strain-rate jump tests and loading-unloading creep tests, are conducted. The effects of loading rate on deformation behaviors of frozen soil are considered based on the constant-strain-rate uniaxial test results. Through the strain-rate jump tests, a new strain rate sensitivity coefficient and a new relationship between the strength of frozen loess and strain rate are established. In addition, the negative effect of sample discrepancies on rote-dependent experimental investigation can be solved well by the strain-rate jump tests. The loading-unloading creep tests can decouple the components of elastic and plastic deformations from the total deformation and obtain the elastic modulus. A uniaxial phenomenon elastic-plastic constitutive model, which incorporates loading rate and temperature-dependent, is proposed on the basis of experimental results. Finally, the proposed constitutive model is validated by some additional tests. And the validation shows that the model can well describe the deformation behaviors of frozen loess under different loading rates and temperatures.