抄録
The soil-water characteristic curve (SWCC) of soil plays the key roll in unsaturated soil mechanics which is a relatively new field of study having wide applications particularly in Geotechnical and Geo-environmental Engineering. To encourage the geotechnical engineers to apply unsaturated soil mechanics theories in routine practice, numerical methods, based on the SWCC and saturated soil properties, have been developed to predict unsaturated permeability function and unsaturated shear strength properties which are expensive and time consuming to measure in laboratories. Further, several methods have been proposed to predict the SWCC in order to avoid difficulties in measuring the SWCC in laboratories. It is time consuming and it may require special techniques or apparatus to measure the SWCC in laboratories. However, it is important to have laboratory measured data of SWCCs to enhance and verify the proposed numerical methods. Hence, employing a Tempe pressure cell apparatus, the present study aims to investigate the effects of dry density and grain-size distribution on the SWCCs of sandy soils. Drying and wetting SWCCs were obtained for four sandy soils with different dry densities. The test data were best-fitted using the Fredlund and Xing (1994) equation and found that the fitting parameter, a, increases linearly with increasing the air-entry value of the SWCC and the fitting parameter, m, decreases with increasing the residual suction of the SWCC. The results revealed that soils with a low density have lower air-entry value and residual suction than soils with a high dry density. Further, the maximum slope of drying SWCC and hysteresis of drying and wetting SWCCs decrease with increasing density of soil. The air-entry value, residual suction, and hysteresis (the difference between the drying and wetting SWCCs) tends to decrease when the effective D10 of the soil increases. A soil with uniform grain-size distribution (the steeper slope in grain-size distribution) has a less hysteresis and a greater slope of drying SWCC than those of a non-uniform soil.
