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基于双重塑性机制,即剪切滑移和加载湿陷机制,及毛细滞回和变形间的耦合作用,提出了一个适用于非饱和黏土的状态相关本构模型。建立了该模型的隐式积分算法,并处理了双重固相屈服面交点处的应力积分问题。考虑了吸力与应力间的关系,推导了本构关系的一致性切线模量。最后,利用该模型预测了一组非饱和黏土的三轴试验,以此反映模型的描述能力;对比了不同应变步长下应变控制试验的计算结果,并以此验证算法的收敛性和准确性;利用有限元程序平台U_DYSAC2计算了二维情况下非饱和土地区地基固结问题,从而验证所得一致性切线模量的有效性。
Based on the dual plasticity mechanisms, shear-slip and loading-collapsing mechanism and coupling between capillary hysteresis and deformation, a state-dependent constitutive model for unsaturated clay is proposed. The implicit integration algorithm of this model is established and the stress integral problem at the intersection point of the dual solid phase yield plane is solved. Considering the relationship between suction and stress, the consistent tangent modulus of the constitutive relation is deduced. Finally, the model is used to predict the triaxial tests of a group of unsaturated clays to reflect the descriptive ability of the model. The calculation results of the strain control tests under different strain steps are compared and the convergence and accuracy of the algorithm are verified The finite element program platform U_DYSAC2 was used to calculate the two-dimensional foundation consolidation problem in unsaturated soil so as to verify the validity of the obtained consistent tangent modulus.