不等幅值循环荷载下冻土残余应变研究及其CT分析

Study on residual strain of frozen soil and CT analysis under cyclic loading of variable amplitudes

基于不等幅值循环荷载作用下低温三轴振动试验资料,研究了冻结粉质粘土在分级往返加荷情况下的残余应变产生条件。根据冻土的残余应变与其温度、振次、含水量等因素的关系曲线,得到了随着温度的降低残余应变值减小、随着振动次数的增加残余应变值增大;含水量的变化对其影响很小的结论。根据冻土试样震融沉前后CT测试数据及扫描图像,定量地分析了土样结构微裂纹发展、密度变化规律,并对冻土特有的震融沉形成机理给予解释。

By means of the experimental data from dynamic triaxial stress-strain test of variable cyclic amplitude for frozen soil, the formative conditions of residual strain on frozen silt clay are studied. It is concluded that the residual strain of frozen soil decreases as the temperature falls, increases with the vibratory times at the same temperature level; and the change of water content has a little effect on it, through the relationships of residual strain versus temperature, vibratory time and water content. The variation laws of structural hair cracking and the characteristics of density for frozen soils are analyzed quantitatively based on the CT scanning results of frozen silt clay before and after dynamic triaxial test. And the formation mechanism of seismic-thaw-settlement of frozen soils is interpreted.