考虑结构性影响的原状黄土本构关系

将三轴应力条件下同一应变的原状黄土主应力差与扰动饱和黄土主应力差之比定义了一个定量化结构性参数mε,它综合反映了土的排列和胶结特征所表现出的综合结构势。结构性参数的变化量与轴应变关系可以用双曲线来拟合,由此所得到的结构性参数表达式可以反映围压、湿度、密度、应力和应变对结构性的影响。结构性参数对不同含水率下原状黄土的应力-应变曲线有很好的归一化作用,归一化后的结构性应力-应变曲线可用符合邓肯-张模型的扰动饱和土应力-应变关系来描述。在扰动饱和土本构关系中引入结构性参数所得到的原状黄土本构关系能够考虑原状黄土结构性的影响,且可以描述软化型和硬化型的应力-应变关系,计算结果与试验结果之间吻合较好。

Constitutive relationship of intact loess considering structural effect

A quantitative comprehensive structural parameter is defined using ratio of principal stress difference of intact loess to that of disturbed saturated loess under triaxial stress condition, which can not only reflect arrangement but also coherent structure of soil particles. The relationship between variation quantity of the structural parameter - and axial strain can be fitted with hyperbola ( is initial structural parameter), equation of the structural parameter obtained with which can reveal the influence of confining pressure, water content, density, stress and strain on structure of intact loess. The structural parameter can make stress- strain curves of intact loess under different water content normalize to structural stress-strain curves which can be described using that of disturbed saturated loess at the same confining pressure simulated with the model proposed by Duncan and Chang. A constitutive relation describing stress-strain behaviour of intact loess is presented by introducing the structural parameter to that of disturbed saturated loess, which can consider structural effect and describe both hardening and softening stress-strain behaviour. Its rationality is confirmed by the agreement of results calculated by using this relation with that tested.