单轴分级循环加载时冻结粉质黏土的动力特性试验研究

Experimental Study of the Dynamic Characteristics of FrozenSilty Clay under Uniaxial Step Cyclic Loading

摘要:

为研究冻结黏土的动力特性，在不同温度（-0.6℃，-1.0℃，-1.5℃）和不同频率（0.5 Hz，1.0 Hz，1.5 Hz，2.0 Hz，3.0 Hz）时开展单轴分级加载试验。结果表明，随动应变幅的增加，温度和加载频率对土的动刚度、阻尼特性和残余应变特性的影响越来越显著；骨干曲线均呈线性变化特征，相同动应变幅时动刚度随温度的降低和频率的增加而增大；阻尼比随动应变幅的增加先增加再逐渐减小，加载末期呈略微增加趋势；相同动应变幅值时阻尼比随温度的降低和频率的增加而减小；同一级荷载下残余应变随循环次数呈线性不断增加，加载级数越高，残余应变增长越快；不同温度和频率时dε_pd/dt随动应变幅的增加而增大，相同动应变幅时dε_pd/dt随温度的升高和频率的降低而增大。

Abstract:

To study the dynamic characteristics of frozen clay, uniaxial step loading tests were carried out at different temperatures (-0.6, -1.0, -1.5℃) and different frequencies (0.5, 1.0, 1.5, 2.0, 3.0 Hz). The results showed that the influence of temperature and loading frequency on the dynamic stiffness, damping property, and residual strain characteristics of soil becomes increasingly apparent with increasing dynamic strain amplitude. The backbone curves linearly change, and at constant dynamic strain amplitude, the dynamic stiffness increases as the temperature decreases and the frequency increases. The damping ratio increases first and then decreases gradually with increasing dynamic strain amplitude, and slightly increases at the end of loading. With the same dynamic strain amplitude, the damping ratio decreases with decreasing temperature and increasing frequency. The residual strain linearly increases with the number of cycles under the same load; the higher the loading grade, the faster the residual strain grows. At different temperatures and frequencies, dε_pd/dt increases with increasing dynamic strain amplitude, and at constant dynamic strain amplitude, dε_pd/dt increases with increasing temperature and decreasing frequency.