超固结非饱和土的弹塑性双面模型

为了研究超固结非饱和土具有的应变软化和剪胀等复杂的力学特性，在弹塑性理论框架内，将巴塞罗那基本模型（BBM）与一种可描述材料循环塑性的硬化法则相结合，建立一个在静态及循环荷载作用下超固结非饱和土的弹塑性双面模型。该模型含有一个边界面和一个加载面，二者在应力空间中随着加卸载进行演化。采用径向映射法则和移动的记忆中心原理来反映超固结非饱和土的循环塑性特征。模型考虑了吸力和超固结的影响，在吸力等于零的时候退化为饱和黏性土的弹塑性双面模型；在无超固结且吸力不等于零的情况下退化为BBM模型。通过与相关静态试验数据的比较，所建模型可以较好地反映静态加载下超固结非饱和土的力学特征；此外，还利用模型对超固结非饱和土的动态力学特性进行了预测。

Elastoplastic two-surface model for overconsolidated unsaturated soils

In order to investigate the complex mechanical characteristics of overconsolidated unsaturated cohesive soils such as strain-hardening and shear dilatancy,an elastoplastic two-surface model for overconsolidated unsaturated soils under static and cyclic loading is established in the framework of elastoplastic theory by combining the Barcelona Basic Model (BBM) and a hardening rule describing the cyclic plasticity of materials. The proposed model contains a bounding surface and a loading surface, which evolve according to the loading and unloading conditions in the stress space. Radial mapping rule and principle of mobile memory center are adopted to reflect the cyclic plastic characteristics of overconsolidated unsaturated cohesive soils. The model takes into account the influence of suction and overconsolidated ratio (OCR). Moreover,the proposed model is able to be changed into the elastoplastic two-surface model for saturated cohesive soils and BBM while the suction of overconsolidated unsaturated cohesive soils is zero and the consolidation behaviour of unsaturated cohesive soils disappears respectively. The comparison between static experimental results and model simulations shows that the proposed model is capable of describing the static mechanical behaviour of overconsolidated unsaturated cohesive soils. In addition,some typical dynamic mechanical behaviour of overconsolidated unsaturated cohesive soils under cyclic loading is predicted.