Uniaxial tests on frozen loess and its constitutive model

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 rate-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.