尺寸和加载速率对冻结水泥土单轴压缩影响

为揭示尺寸效应和加载速率效应对冻结改良土力学特性的影响规律，以冻结水泥改良土为研究对象，开展了不同尺寸与加载速率条件下的单轴压缩试验，通过分析试验数据，讨论了高径比和加载速率对试样强度与变形特性的影响。研究结果表明，高径比影响试样的应力-应变曲线类型及峰值后的变形特性。高径比增加，应力-应变曲线出现明显弹性屈服点，峰后脆性增强，试样破坏形式由劈裂破坏变为单一剪切破坏。试样的抗压强度、切线模量、起始屈服模量、破坏应变随高径比变化均可用抛物线进行拟合，综合考虑，推荐试验宜采用高径比为1.62~2.02的试件。在试验设定的温度和加载速率条件下冻结水泥土的单轴压缩应力-应变关系均为应变软化型。与冻土类似，冻结水泥土的抗压强度与起始屈服强度同样随温度的降低和加载速率的增加而增大。不同温度下冻结水泥土抗压强度与加载速率的关系可用幂函数表示。温度越低，起始屈服强度受加载速率影响越大。温度和加载速率对冻结水泥土切线模量也有较大影响，不同加载速率条件下切线模量与温度呈线性关系。冻结水泥土的破坏应变随温度的降低和加载速率的增加而增大，在1.94%~6.94%之间变化，不同加载速率条件下破坏应变与温度呈幂函数关系。

Effect of size and loading rate on the uniaxial compression characteristics of frozen cement soil

In order to reveal the influence law of the effect of size and loading rate on the mechanical properties of frozen modified soil, uniaxial compression tests with different sizes and loading rates are carried out on the frozen cement modified soil. The influence of height-diameter ratio and loading rate on the strength and deformation characteristics of the specimen is discussed by analyzing the test data. The results show that the high-diameter ratio affects the stress-strain curve type and the post-peak deformation characteristics of the sample. With the increasing high-diameter ratio, the stress-strain curve shows a significant elastic yield point, and the post-peak brittleness increases, and the failure mode of the sample changes from splitting failure to single shear failure. The compressive strength, tangent modulus, initial yield modulus and strain at failure of the specimen can be fitted by using a parabola with the change of height-diameter ratio. For the comprehensive consideration, the test specimen with high-diameter ratio of 1.62~2.02 should be used. Under the conditions of temperature and loading rate, the uniaxial compressive stress-strain relationship of the frozen cement soil is strain softening. The compressive strength and initial yield strength of the frozen cement soil, similar to that of the frozen soil, increase with the decreasing temperature and the increasing loading rate. The relationship between the compressive strength and loading rate of the frozen cement soil at different temperatures can be expressed by using a power function. The lower the temperature, the greater the influence of the loading rate on the initial yield strength. Temperature and loading rate also have a great influence on the tangential modulus of the frozen cement soil. The tangent modulus has a linear relationship with temperature under different loading rates. The failure strain of the frozen cement soil increases with the decreasing temperature and the increasing loading rate, which varies from 1.94% to 6.94%. Under different loading rates, the failure strain has a power function relationship with temperature.