由滞回曲线的形态特征分析冻结黏土的动力特性

Analysis of dynamic properties of frozen clay by morphological characteristics of hysteresis curves

利用滞回曲线研究冻结黏土的动力学特性。结果表明,当土体温度为-0.5℃^-4℃、荷载频率为1~10 Hz时,随温度的降低和动荷载振动频率的增加,冻结黏土的刚度逐渐增大,黏滞性、细观损伤程度、塑性变形和能量耗散能力逐渐减小,当土中温度低于-4℃或荷载频率高于10 Hz时,土的动力特性变化不明显;随动应力幅值的增大,刚度逐渐减小,黏滞性、细观损伤程度、塑性变形和能量耗散能力逐渐增大;相同动应力幅值下,刚度、黏滞性、细观损伤程度、塑性变形和能量耗散能力受温度影响最大,围压影响最小,频率影响居中;试验温度、频率和围压三因素对冻结黏土的细观损伤程度和塑性变形能力影响程度最大,对黏滞性和耗能能力的影响程度基本相同,位于第二,对刚度的影响程度最小。

The dynamic properties of frozen clay are studied by hysteresis curves. The test results show that when the temperature of frozen clay is-0.5 ℃--4 ℃ and the vibration frequency is 1-10 Hz, the stiffness increases, but the viscosity, degree of microscopic damage, residual strain and energy dissipation decreases with the decreasing temperature and increasing vibration frequency. There is no apparent change in the dynamic properties due to the stability of the mechanical properties of frozen clay while the soil temperatures are less than-4 ℃ and the vibration frequencies are greater than 10 Hz. With the increasing dynamic stress amplitude, the stiffness decreases; but the viscosity, degree of microscopic damage, residual strain and energy dissipation increases gradually. With the same dynamic stress amplitude, the influence degree of temperature, vibration frequency and confining pressure on the dynamic properties of frozen clay is maximum, middle and minimum. The degree of microscopic damage and residual strain are affected by temperature, vibration frequency and confining pressure apparently. The viscosity and energy dissipation are affected secondly, and the stiffness is impacted minimally.