Abstract
Rain-induced landslides are common around the world. To analyse transient seepage and to predict porewater
pressure distribution in unsaturated slopes subjected to rainfall infiltration, it is essential to study soil-water characteristics
and water permeability functions. The soil-water characteristic curve (SWCC) is a relationship between suction
and water content or degree of saturation. Conventionally, only the drying soil-water characteristic curve of soil
specimens is determined in a pressure-plate extractor without the application of any external stress. In this paper, the
influences of initial dry density and initial water content, history of drying and wetting, soil structure, and the stress
state upon the desorption and adsorption soil-water characteristics of a completely decomposed volcanic soil in Hong
Kong are examined and discussed. The experimental results presented are obtained by using a conventional volumetric
pressure-plate extractor and a newly modified one-dimensional stress-controllable pressure-plate extractor with deformation
measurements. The SWCC of a recompacted specimen is very different from that of a natural specimen with the
same initial soil density and initial water content. The SWCC of the recompacted specimen is highly dependent on the
history of drying and wetting. The rates of desorption and adsorption are substantially higher at the first drying and
wetting cycle than at the second drying and wetting cycle. The size of the hysteresis loop of the recompacted specimen
is considerably larger than that of the natural specimens. The SWCC of soil is stress-state dependent. For recompacted
specimens subjected to different stress states, the higher the applied stresses, the lower the rate of desorption and the
smaller the size of the hysteresis loops. However, for natural specimens, the size of the hysteresis loops seems to be
independent of the stress state. Under a higher applied stress, natural specimens exhibit lower rates of desorption and
adsorption.
Full Context:
https://drive.google.com/file/d/0B4hiGhsfDllxVFdEeFJ3ZHF6cVU/view
