动力荷载作用下冻土变形特性研究

STUDY ON DEFORMATION CHARACTERS OF FROZEN SOIL UNDER LONG-TERM DYNAMIC LOADING

基于等幅值循环荷载作用下低温三轴振动试验资料,研究冻结青藏铁路北麓河黏土在长期往返加荷情况下的变形特征。根据不同温度、动应力幅值、频率、围压等因素下冻土的应变与振次关系曲线,得到随着振动次数、动应力幅值、围压的增加残余应变增大;随着温度的降低残余应变值减小,高温冻土对动力作用敏感;存在某一临界频率(6Hz左右),当频率大于或小于临界频率,残余应变增加速度都将增大的结论,并合理解释冻土特有的振融沉陷的成因机理。

Based on dynamic tri - axial test at low temperature, deformation behaviors of clay sampled from BeiLu River section of Qinghai - Tibet railway were studied under long - term cyclic loading. According to the relation curves between residual strain and vibration times of frozen soil at different negative temperatures, frequency, confining pressure and water content, three conclusions are drawn as follows： With the increase of vibration times, the dynamic loading and confining pressure, residual strain increase; with the decrease of the temperature, residual strain will decrease, the high temperature frozen soil is sensitive to the dy- namic loading; there exists a critical frequency （about 6Hz）.When the frequency is higher or lower than the critical frequency, the residual strain changes. Moreover, the mechanism of settlement for frozen soil was explained.