适用于吸力循环作用的膨胀性非饱和土本构模型

首先从颗粒尺度基于热力学理论对干湿循环路径下膨胀土的变形行为产生的机理进行了论述。通过分析可知,吸力循环作用下膨胀性非饱和土的塑性变形不仅取决于土中集聚体之间的重新排列,而且与集聚体内储存的塑性势能的变化相关。其次基于BBM模型建立了一个适用于吸力循环作用的膨胀性非饱和土的弹塑性本构模型。模型中通过吸力变化屈服面和混合硬化准则描述上述两种不同作用机理所产生的塑性变形。最后利用该模型对膨胀性非饱和土在吸力循环作用下的行为进行了预测。通过预测结果与试验数据的比对可知：该模型能够较好地描述膨胀性非饱和土在吸力循环作用下产生的累积塑性变形,及其随着循环次数的增加趋向于稳态的特性。

Constitutive model for unsaturated expansive soils under suction cycles

At the particle scale, the theory of thermomechanics is employed to describe the mechanism of mechanical behaviors during suction cycle paths. By means of the analysis, the plastic deformation can be decomposed into two parts, which are attributed to the structural rearrangement and change of stored plastic work, respectively. Moreover, a new constitutive model for unsaturated expansive soils is proposed, which adopts the suction-change yield surface and combines the isotropic-kinematic hardening rule to consider the mechanism of plastic deformation. The predictions are made based on the test results of suction cycles published in public. The comparisons between the measured and predicted results indicate that the proposed model can quantitatively predict the behaviors of unsaturated expansive soils under suction cycles.