【摘要】 基于黏弹性理论,将动态弹性模量的最大值定义为冻土的动模量,通过计算滞回曲线中直线斜率的方法来计算冻土的动模量。通过动三轴试验,对不同频率、围压和负温条件下冻土的动模量随动应变幅的变化规律进行了试验研究,结果表明:在不同频率(0.1～20 Hz)、围压(0.3～2 MPa)和负温(-0.2～-2℃)条件下,青藏黏土的动模量取值范围为393～1749 MPa,兰州黄土的动模量取值范围为101～713 MPa;同一级加载下,动模量随着振次的增加基本不变,可以采用平均值来表征该级加载下的动模量;对于青藏黏土和兰州黄土,不同频率条件下,动模量随动应变幅的增加最终趋于一稳定值,该稳定值随加载频率的增加而增大;不同温度和围压条件下,随着动应变幅的增加,动模量先减小再趋于一个稳定值,该稳定值随围压的变化较复杂,随温度的降低而增大。更多还原

【Abstract】 Based on the viscoelastic theory,the slope of the middle straight line in the hysteresis curve is adopted to define dynamic elastic modulus.Dynamic triaxial tests are employed to study the variation tendency of dynamic elastic modulus with dynamic strain amplitude varing under different vibration frequencies,confining pressures and negative temperatures conditions.The results show that the dynamic elastic modulus values of Qinghai-Tibet clay range from 393 to 1749 MPa,and those of Lanzhou loess range from 101 to 713 MPa with vibration frequencies of 0.1～20 Hz,confining pressure of 0.3～2 MPa and negative temperatures of-0.2～-2℃.Because the dynamic elastic modulus changes slightly with the increasing vibration cycles at the same loading level,the average value is adopted.The dynamic elastic modulus tends to be stable eventually with the increasing dynamic strain amplitude.The stable value of dynamic elastic modulus increases with the increasing vibration frequencies and decreasing temperatures.When the confining pressure changes,the stable value of dynamic elastic modulus changes without unified law.更多还原