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通过室内动三轴试验,研究了甘南地区次生黄土的动本构关系,得到了模型参数,分析了甘南黄土的动剪模量比和阻尼比发展特征,提出了动剪切模量衰减模型和阻尼增长模型;并通过归一化处理和模型参数比较,对次生黄土与风成黄土动剪模量比和阻尼比的差异性进行了讨论。结果表明:次生黄土的动本构关系服从双曲线模型,模型参数a值较风成黄土无明显差异,但b值为相同条件下风成黄土b值的1.5~3倍,且模型参数与天然含水率、干密度等物性参数和固结围压不存在明显的相关性。次生黄土的初始动弹性模量E_(dmax)受固结条件、密度影响较大,相同条件下残坡积黄土的E_(dmax)较冲洪积黄土小。次生黄土的动剪模量比随动剪应变增大而减小,变化趋势满足负指数衰减模型;阻尼比随动剪应变的增大而增大,变化趋势服从对数关系;相比于风成黄土,其动剪模量比随动剪应变的增加衰减更快,阻尼比增长范围较窄,表明沉积环境对黄土动力特性的差异性影响显著。
The dynamic constitutive relationship of secondary loess in Gannan area was studied by indoor triaxial test. The model parameters were obtained. The dynamic shear modulus ratio and damping ratio development characteristics of Gannan loess were analyzed. The dynamic shear modulus attenuation model And damping growth model. The differences of dynamic shear modulus ratio and damping ratio between secondary loess and aeolian loess were discussed by normalization and comparison with model parameters. The results show that the dynamic constitutive relationship of the secondary loess obeys the hyperbolic model and the model parameter a has no significant difference compared with the aeolian loess, but the b value is 1.5-3 times of the b value of aeolian loess under the same conditions, and the model parameters are similar to the natural Water content, dry density and other physical parameters and consolidation of confining pressure is not obvious correlation. The initial elastic modulus E dmax of secondary loess is greatly affected by the consolidation conditions and density. Under the same conditions, the E dmax of the residual loess plot is smaller than that of the red loess loess. The dynamic shear modulus of secondary loess decreases with the increase of dynamic shear strain, and the change trend meets the negative exponential decay model. The damping ratio increases with the increase of dynamic shear strain, and the change trend obeys the logarithmic relationship. Aeolian loess has a faster dynamic shear modulus and a narrower range of damping ratio than that of dynamic shear strain, indicating that the sedimentary environment has a significant effect on the dynamic characteristics of loess.