Experimental study on dynamic strain rate of frozen soil from railway embankment of Qinghai-Tibet railway in China

Based on dynamic tri-axial tests at low temperature,the deformation behavior of frozen silty clay from railway embankment of Qinghai-Tibet railway was studied under stepped axial cyclic loading.Time history curves of residual strain of frozen soil were investigated under different negative temperatures,frequencies,confining pressures and water contents.Conclusions were drawn as follows: the dynamic load greatly affected axial strain rate;the axial strain rate linearly increased with the increasing of stress ratio and confining pressure,while decreased with decreasing of temperature,increasing of frequency and water content.According to the test data,an exponential function was brought forward to fit the relation between stress ratio,negative temperature,water content,frequency and axial strain rate.Then,the mechanism of settlement for frozen soil,caused by vibration exciting defreeze was explained.The study was helpful for the settlement prediction of projects like Qinghai-Tibet railway induced by residual deformation of frozen soil under traffic load.It was important to further study the railway embankment settlement caused by train steering,and the experimental data for fatigue model of frozen soil were also provided.