循环加载条件下土的应力路径本构模型

土的应力应变关系与应力路径密切相关，充分接近的两条加载路径所产生的变形基本相同，因此可将任意应力路径转化为与其充分接近且易于计算变形的应力路径，从而获得变形。在此基础上，本文通过定义两个应力状态的参量，分别描述等应力比循环加载和等平均应力循环加载条件下土的塑性变形规律，以及两者的相互影响，并给出一个新的加卸载准则，在不增加任何土性参数的条件下，将现有的土的应力路径本构模型扩展应用于循环加载条件，建立了循环加载条件下土的应力路径本构模型。通过与试验结果的比较表明，本文提出的循环加载模型可较合理地反映土在往复荷载作用下的变形特性。模型简单易用，只含5个土性参数，并具有明确的物理意义。

Constitutive model for soils under the condition of cyclic loading

The stress strain relationship of soils is closely related to the stress path. Generally, if the loading stress paths of the soil are enough close to the same their stress strain relationship must be basically the same. Sequentially, an arbitrary stress path can be transform into another almost similar stress path for which the strain is more easily to be calculated, so that the constitutive model for such soils can be established. On the basis of this idea, a new constitutive model adaptive to the condition of cyclic loading is established. In the model two parameters describing the plastic deformation laws under the conditions of constant stress ratio loading and constant mean stress respectively are introduced and a new criterion of loading unloading is suggested. The comparison with experimental result shows that the proposed model reasonably reflects the deformation characteristics of soils under the condition of cyclic loading and is simple in form, in which only five parameters of soil property are involved.