非饱和土一维压缩试验及变形规律探讨

为研究非饱和土在侧限条件下的变形规律,进行了控制初始干密度和基质吸力的一维压缩试验,提出切线压缩系数和切线体积压缩系数的概念,发现切线压缩系数和切线体积压缩系数均随净竖向压力的增大呈指数衰减规律,建立了描述孔隙比–净竖向压力关系和竖向应变–净竖向压力关系的经验模型,结合国内外文献中的试验数据对模型的合理性及其对不同类别非饱和土的适用性进行了验证。提出的模型可用于计算任意压力间隔内非饱和土的平均压缩性指标,计算非饱和土由于浸水产生的一维湿化变形,还可用于描述非饱和土随基质吸力增大的一维收缩变形规律。

One-dimensional compression tests and deformation rules of unsaturated soils

In order to study the deformation rules of unsaturated soils under lateral confinement, a series of one-dimensional compression tests are carried out under controlled initial dry density and matric suction. The concepts of tangent compressibility coefficient and tangent volume compression coefficient are proposed. Results of the study indicate that the tangent compressibility coefficient and tangent volume compression coefficient decay exponentially with the increasing net vertical pressure. Based on this law, two empirical models, which can describe the variations of void ratio and vertical strain with the net vertical stress, are established. The rationality of the proposed models and their applicability to various types of unsaturated soils are verified using the test data in other literatures. The proposed models can be used to calculate the mean compressibility indexes within arbitrary pressure interval, to compute the slaking deformation of unsaturated soils due to the increase of moisture content, and also to describe the variation of void ratio with the matric suction.