分级加载下冻结黏土的动应变幅变化特征

The characteristics of dynamic strain amplitude of frozen clay with stepped axial cyclic loading

动应变幅反映土的振动特征和阻尼特性,温度影响土中水的形态,从而影响动应变幅的大小.采用MTS-810型三轴试验机对一系列温度下黏土的动应变幅变化特征进行研究,结果表明:仪器误差、操作误差等可能使试验结果具有变异性,可采用取平均值的方法来减小试验结果的变异性.动应变幅随加载级数的增加逐渐增大.当温度高于土中水的冻结点时,温度变化对动应变幅的影响较小;当温度低于土中水的冻结点时,随温度的降低,动应变幅变化较显著;当温度低于-4℃时,随温度的降低动应变幅几乎不发生改变.动应变幅随动应力幅的增大呈线性增大趋势.

The water form in the clay is affected by temperature,consequently affected dynamic strain amplitude of clay. The MTS-810 dynamic triaxial apparatus is used to make researches on the dynamic strain amplitude variation characteristics of frozen clay at a series of temperature. The results showthat the dynamic tri-axial test results will be made variable by the instrumental error,operate miss and so on. And the method of repeated trials can be used to eliminate the variability of the test results. The dynamic strain amplitude increases when the load series increases. When the temperature is higher than the freezing point of water in clay,the change of temperature has less effect on dynamic strain amplitude. Inversely,when the temperature is lower than it,the dynamic strain amplitude changes significantly with the decreasing of temperature. When the temperature is lower than- 4 ℃,the relationship curve of dynamic stress amplitude and dynamic strain almost coincide with the decrease of temperature. Dynamic strain amplitude increases linearly with the increase of dynamic stress amplitude.