黄土的修正上下加载面模型研究

由于天然沉积的黄土具有显著地结构性，在湿度及荷载变化条件下，其宏观力学特性发生显著的变化。为了分析增湿和加载条件下黄土的结构性损伤演化特性及应力-应变关系的变化特性，引入上、下加载面的概念，在原有超固结及结构性参数的基础上，考虑了含水率变化的影响，定义了新的初始超固结及结构性参数；运用上、下加载面概念，通过引入构度及黄土结构屈服强度，推导了结构性黄土的一般应力-应变关系，并进行了参数的影响变化分析；最后，通过不同含水率条件下的黄土压缩及三轴试验数据与模型预测数据的对比分析，验证了模型的合理性。

Research on modified super-loading and sub-loading yield surface model of loess

Collapse loess is a special structured soil because of its special sediment environments. When moisture and stress suffered from changing, macromechanical characteristics would change significantly. To analyze the stress-strain relationship changing laws and structural damage evaluations of loess under moisture and stress coupling effect, the sub-loading surface and super-loading surface ideas are introduced into soil constitutive model by Asaoka et al, in this paper, based on the original super-consolidation parameter and structural damage evaluation parameter, the effect of water content changing is considered in super-loading and sub-loading surface constitutive model; and new initial super-consolidation parameter and structural damage evaluation parameter are defined. Base on the sub-loading surface and super-loading surface ideas, the general stress-strain relationships are derived by introducing structural index and structure yield strength into constitutive model; at the same time, the effects of parameters are analyzed. Finally, the accuracy and rationality of the constitutive model proposed are verified by comparing with experimental results of collapse loess in oedometer tests and conventional triaxial tests conditions and calculating results of constitutive model proposed in this paper.