高速铁路粗粒土填料动力参数试验研究

Experimental research on dynamic parameters of high-speed railway coarse-grained padding

采用大型动三轴仪对高速铁路路基粗粒土填料进行实验研究,分析应力水平、固结围压、振动频率以及振动次数对动弹性模量和阻尼比的影响。结果表明:粗粒土填料的动应力与动应变的关系可采用双曲线本构模型描述;随着动应变的增加,动弹模量减小,阻尼比增加。粗粒土填料的动弹性模衰减主要集中在应变小于0.075%的范围内,阻尼比的增加主要集中在应变小于0.015%的范围内;随着固结围压的增大,动弹模增大,阻尼比增加。围压对动弹模量的影响主要集中在应变小于0.01%的范围内,对阻尼比的影响主要集中在应变大于0.01%的范围内;随着加载频率的增大,动弹模增大,阻尼比增加。频率对动弹模量的影响主要集中在应变小于0.075%的范围内,对阻尼比的影响主要集中在应变大于0.015%的范围内。低频时阻尼比增加的幅度大于高频时阻尼比增加的幅度;随着振动次数的增加,动弹模减小。在动应力水平较低时,振动次数对粗粒土填料动弹模的影响较小;在动应力水平较高时,振动次数越大,粗粒土填料动弹模的衰减量越大。

The influence of the stress level, confining pressure, vibration frequency and number of vibration on dynamic elastic modulus and damping ratio of high - speed railway coarse - grained padding was studied by large - scale dynamic triaxial apparatus. Experimental results indicate that the correlation of dynamic stress and dynamic strain for coarse -grained soil padding can be described with the hyperbolic constitutive model. With the increase of dynamic strain, the dynamic elastic modulus decreases while the damping ratio increases. The attenuation of dynamic elastic modulus concentrates mainly on the range of strain less than 0. 075% , and the damping ratio increases mainly in the range of strain less than 0. 015%. Meanwhile, the dynamic elastic modulus and damping ratio increase with the increasing value of the confining pressure. Thereinto, the impact of confining pressure on dynamic elastic modulus is mainly in the range of strain less than 0.01% , while the effect on damping ratio mainly more than 0.01%. As the loading frequency increases, the dynamic elastic modulus and the damping ratio tend to increase. The impact of frequency on dynamic elastic modulus is mainly in the range of strain less than 0.075%, while the effect on damping ratio mainly more than 0.01%. Moreover, the incremental value of damping ratio at low frequency is larger than that at high frequency. With the increasing number of vibration, dynamic modulus reduces. The number of vibration has little effect on the dynamic elastic modulus of coarse - grained soil under the low dynamic stress level. When the dynamic stress level is relatively high, the at- tenuation of dynamic elastic modulus increases with the increasing number of vibration.