真三轴应力条件下修正邓肯-张模型的试验研究

Experimental study of modified Duncan-Chang model under true triaxial stresses

邓肯-张非线性模型已经被广泛的应用于工程实践的应力-应变数值分析中。考虑轴对称应力条件下邓肯-张模型应用于复杂应力时存在的不足,依据原状土的真三轴试验数据对邓肯-张模型预测结果与实测结果进行比较,论证了复杂应力条件下邓肯-张模型的适用性。通过考虑真三轴试验应力条件下中主应力对大主应变的影响,邓肯-张E-B模型大主应变叠加中、小主应力差作用产生的变形,提出了不同中主应力比的邓肯-张E-B模型参数确定方法,建立了复杂应力路径条件下修正的邓肯-张E-B模型。经与西安原状土真三轴试验结果进行比较,验证了修正邓肯-张E-B模型的正确性,为邓肯-张模型在复杂应力条件下的应用提供了途径。

Duncan-Chang nonlinear model has been widely used in numerical analysis of stress-strain in engineering. There exists insufficiency when Duncan-Chang model applied to complex stress conditions; this model is based on the axisymmetric stress conditions. We compared the model predictions with the experimental results of intact clay by true triaxial tests. The results demonstrate the applicability of Duncan-Chang model under complex stress condition. According to the analysis of the relationship between intermediate principal stress and the maximum principal strain under true triaxial stress conditions, and the maximum principal strain includes not only the maximum principal strain but also the strain, is caused by differences between the intermediate principal stress and the maximum principal stress. Based on Duncan-Chang E-B model, we proposed a method for determining Duncan-Chang E-B model parameter under different intermediate principal stress ratios and also established the modified Duncan-Chang model E-B model under complex stresses. The modified Duncan-Chang E-B model is reliable by comparison of the true triaxial test results of Xi＇an intact clay; it is shown a way to use Duncan-Chang E-B model in complex stresses path.