考虑基质吸力变化时非饱和土的一维本构模型

当地下水位上升或地面遇水浸润时，土的饱和度将因毛细作用而变化，以此使土体产生变形。其中由于含水量增加而使土的重度增大，从而引起压缩变形；同时含水量的增加而使基质吸力下降，从而引起土的回弹变形，因此最终变形取决于上述两种变形趋势的综合效应。根据广义Hook定律、Fredlund的双应力状态变量及Brooks和Corey关于基质吸力与饱和度之间的经验关系，建立了K0状态下非饱和土的一维本构模型。将这一模型与分层总和法相结合，可以计算基质吸力变化时土的竖向变形。通过研究发现，非饱和土的地面变形不仅取决于土的性质与土层的厚度，而且依赖于土中吸力变化前后的分布及应力状态等因素。所建议的一维本构模型可以用于非饱和土地基上基础的沉降估算。

One-dimensional constitutive model of unsaturated soil considering change of matric suction

Unsaturated soils will undergo deformation as ground is soaked or underground water table rises. The increase in water content can result in, on one hand, compression due to rise in specific weight of soil, and, on the other hand, rebound due to decrease in matric suction. The comprehensive effect is controlled by these two types of factors. Based on generalized Hook’s law of elasticity, Fredlund’s theory of two stress state variables and the empirical relationship between matric suction and saturation given by Brooks and Corey, an incremental-type of constitutive model is established for unsaturated soils loaded under the condition of K0- consoilidation. Combined with the layer-wise summation method; the proposed model can be used to assess deformation of unsaturated soils induced by the soaking of ground, rise or lowering of water table as well as over-evaporation. The proposed method is used to assess vertical deformation of a soil stratum as an example. It is displayed that deformation characteristics of the unsaturated soil is not only dependent on soil properties, but also associated with the variation of profile suction distribution and thickness of soil layer as well as stress states. The procedure can also be used to evaluate the settlement of footing on unsaturated soil foundation.