分级循环动荷载作用下冻结粉土动剪切模量比与阻尼比分析

Analysis of dynamic shear modulus ratio and damping ratio of frozen silt under hierarchical dynamic loading

冻土作为公路和铁路的路基,其稳定性问题一直被广泛关注和研究。为寻求冻土在交通荷载下的破坏机制,基于低温动三轴试验,以青藏高原冻结路基粉土为研究对象,施加分级循环动荷载。考虑不同冻结温度、含水率、压实度和围压,对冻结粉土的动力学参数进行详细的分析。研究结果表明,动剪切模量倒数与动剪应变呈良好的线性关系,双曲线模型能较好的表达冻结粉土动应力–应变关系特点;冻结温度和含水率变化对动剪切模量比和阻尼比影响显著,且存在最佳冻结温度范围和最佳含水率范围控制其相应最大、最小值;压实度和围压变化对动剪切模量比和阻尼比影响较弱,并未发现存在最优范围。

Frozen soil as a subgrade for roads and railways,which stability has been widely concerned and studied.In order to seek the failure mechanism of frozen soil under traffic load,the cryogenic temperature dynamic triaxial tests is implemented under the hierarchical cyclic dynamic loading.The dynamic parameters of frozen silt soil are analyzed in detail considering different freezing temperatures,water contents,compaction degree and confining pressure.The results show that there is a good linear relationship between the reciprocal of dynamic shear modulus-strain,hyperbolic model can well express the dynamic stress-strain relationship of frozen silt.The freezing temperature and water content change have significant influence on the dynamic shear modulus and damping ratio,there are optimal freezing temperature and water content range to control their corresponding maximum or minimum values.The compaction degree and confining pressure have weak influence on dynamic shear modulus and damping ratio,the optimal range is not found.