粗颗粒土的应力应变特性及其数学描述研究

大型三轴试验研究了粗颗粒土的应力应变特性及邓肯-张模型的适用性。试验结果表明粗颗粒土表现出明显的低围压下体胀高围压下体缩的体变性质，邓肯-张模型在描述粗颗粒土的体变特性方面存在不足。基于试验结果提出了新的体变描述公式，在未增加模型参数的条件下提出了邓肯-张模型的改进模型。采用改进模型对多种粗颗粒土三轴试验结果进行了预测，结果初步表明改进模型能够更好地模拟粗粒土的体变特性。

Study on behavior of coarse grained soil and its modeling

The stress-strain relationship behavior of coarse grained soil was investigated through a series of large-scale triaxial compression tests. The test results show that the coarse grained soil would dilate under low confining pressure and contract under high confining pressure. Duncan-Chang model is not able to properly simulate such significant volumetric strain behavior of the coarse grained soil. A modified model of coarse grained soil is then developed through presenting new volumetric strain assumptions according to the test results. The model is convenient to practical application due to its simplicity in programming and few model parameters which could be easily determined with a similar approach as Duncan-Chang model. The validity of the modified model is preliminarily confirmed in predicting the volumetric strain response of coarse grained soil by triaxial compression test results of several kinds of coarse grained soils.