含水量变化时非饱和土的变形研究

Deformation of Unsaturated Soils Induced by Variation of Water Content

在非饱和状态下土中含水量的增加一方面将引起容重增大 ,从而引起压缩变形 ;另一方面将引起基质吸力的下降 ,从而引起土变形的回弹。非饱和土的最终变形表现为膨胀还是沉降取决于上述 2种变形的综合效应。根据广义Hook定律 ,Fredlund的双应力状态变量 ,以及基质吸力与饱和度的关系理论 ,利用增量原理建立了K0 状态下非饱和土的变形关系表达式 ,利用这一模型可以计算非饱和土含水量变化时的变形问题。研究表明 :非饱和土的变形特性取决于土的性质 ,土中吸力变化前后的分布 ,所考虑土层的厚度以及应力状态等。

The unsaturated soils will undergo deformation as ground smeared or underground water level rose. The increase of water content can result in compression deformation for soil's specific weight rise and rebound for matric suction's decrease. Whether compression or extension is defined by overall effect of the two aspects. Based on increment theory, generalized Hook's law, Fredlund's two stress state variable, Brooks and Corey's theory about relationship between matric suction and saturation, a common constitutional model was established to calculate the deformation of unsaturated soils induced by change of water content under K0 conditions. The result showed that the deformation character of the whole unsaturated soil is defined not only by soil's parameters but also by the suction distribution variety, depth of concerned soil and stress state etc.