非等向固结砂土极小应变刚度的超弹性模型

VERY-SMALL-STRAIN STIFFNESS OF ANISOTROPICALLY CONSOLIDATED SAND:A HYPERELASTIC MODEL

反映砂土极小应变刚度的 Hardin-Richart 公式主要是基于等向固结的实验数据,但是天然土体基本都是处于非等向固结状态。实验研究表明,随着非等向程度的加深,Hardin-Richart 公式对土体刚度的估算偏差越大,误差最大可超过 20%。3 种类型的超弹性模型能够反映土体极小应变刚度随应力水平增大而增大的幂律关系,但仅有 HE1 模型具有弹性剪胀等特殊的正剪耦合特性,对土体非等向固结状态下的刚度规律趋势预测正确。HE1 模型对土体非等向固结状态下的刚度规律预测结果受到其参数取值的影响,但总体而言与实验结果总结的规律一致。

The Hardin-Richart formula used to characterize the very-small-strain stiffness of sands,is mainly based on the experimental data under the isotropic consolidation stress state.The natural soils are anisotropically consolidated.The previous experimental studies have shown that the error of the Hardin-Richart formula will magnify up to 20%as the anisotropic consolidation stress ratio increases.All three different hyperelastic models developed in the soil mechanics literature can reflect the power-law relationship of very-small-strain soil stiffness with respect to the increased mean stress level.But only the HE1 model,accounting for the normal-shear coupling effect including elastic shear dilatation,is capable of modelling the effects of anisotropic consolidation stress ratio on the very-small-strain stiffness.The prediction results of the HE1 model are affected by the values of the model parameters,but generally consistent with the experimental results.