旋转硬化与统一硬化参量在修正剑桥模型中的应用

Application of Rotational Hardening and Unified Hardening Parameter in Modified Cambridge Model

针对修正剑桥模型不能模拟土体剪胀性、应力路径转折时土体的应力应变特性以及应力引起的各向异性,将旋转运动硬化理论引入到修正剑桥模型中,给出了椭圆屈服面的旋转运动硬化机制,把等向硬化的修正剑桥模型扩展为旋转运动硬化模型.同时,为了能够反映砂土和超固结土的剪胀等本构特性,用统一硬化参量H代替修正剑桥模型中的等向硬化参数—塑性体积应变pvε,建立了一个新的基于旋转硬化与统一硬化参量的改进的修正剑桥模型.对修正剑桥模型、旋转运动硬化修正剑桥模型和新模型进行了定性对比,结果表明,新模型不但能够反映应力路径转折时土体的特性,也能描述土体的剪缩和剪胀.

The modified Cambridge model is one of the most popular and fundamental elastoplastic model for soils, but it can＇t simulate the dilatancy of sand,the soil constitutive behavior during large stress reversals and the stress induced anisotropy as well. In view of these shortcomings, the rotational kinematic hardening theory is incorporated into modified Cambridge model, and the rotational hardening mechanism of ellipse yield surface is presented in the paper. Then, modified Cambridge model is extended from isotropic to rotational kinematic hardening in a simple manner. Moreover, in order to simulate the constitutive behavior, such as dilatancy, of sand and overconsolidated soil, the unified hardening parameter H is introduced into the model to replace isotropic hardening parameter, i. e. plastic volumetric strain E~ ,in modified Cambridge model, and then a new model is presented based on rotational hardening and unified hardening parameter. At last, by contrasting the modified Cambridge model, the rotational kinematic hardening modified Cambridge model and the new model,it＇s shown that the new model can not only capture the soil constitutive behavior during large stress reversals,but also reflect the positive/negative dilatancy of soil.