剑桥模型与统一硬化模型对超固结土特性描述的对比分析

ANALYSIS IN BEHAVIORS OF OVER-CONSOLIDATED CLAYS DESCRIBED BY CAM-CLAY MODEL AND UNIFIED HARDENING MODEL

在深入研究修正剑桥模型和统一硬化模型(UH模型)基本特性的基础上,揭示模型描述超固结土特性的机理。对于超固结土,修正剑桥模型的预测曲线存在突变,不能很好地模拟土体连续、渐近的变形过程;对于重超固结土,模型预测的排水路径条件下的峰值强度很高,与实测结果偏差较大。修正剑桥模型不能模拟真三轴试验的应力-应变关系。UH模型的参数与修正剑桥模型相同,通过采用基于空间滑动面准则(SMP准则)的变化应力方法,模型能够合理描述在三轴压缩、三轴伸长和真三轴条件下超固结土的剪胀、硬化和软化特性。

Based on researching the features of the modified Cam-clay model and UH model, the mechanism of model describing the behaviors of the over-consolidated （OC） clays is revealed. For the OC clays, the curves predicted by the modified Cam-clay model have abrupt changing points, so the model cannot model continue and gradual changing process well. For the heavy OC clays, the predicted peak strength is rather higher than test data under the drained condition. The model cannot describe the stress-strain relationships in true-triaxial test. The parameters in UH model are the same as those in the modified Cam-clay model. The model using the transformed stress method based on SMP criterion can rationally model many characteristics of the OC clays well, including shear dilatancy, strain hardening and softening, and stress path dependence behavior.