Effect of Initial Partial Saturation on Collapse Behavior of Glacial Sand with Fines

摘要

Collapsible soils are soils that are susceptible to a significant and sudden reduction in volume upon wetting and loading. This phenomenon is associated with loosely deposited, metastable soil structures, which can withstand a considerable stress in the unsaturated state, but they exhibit an excessive settlement when saturated. Collapsing of soil depends on the initial dry density, initial moisture content and pressure at wetting. Matric suction is also a key factor, which is related to moisture content through the soil water characteristic curve (SWCC). Suction helps to maintain the inter-granular contacts between particles of unsaturated soil. This study investigated the role of matric suction, dry density ratio and wetting pressure on the collapse behavior of three silty glacial sands from South Australia. The drying SWCC of each sand was determined by controlling matric suction between suctions of 1 to 1000 kPa, using the hanging column and pressure plate methods. The one-dimensional collapse potentials of the three different sands were determined at various specimen preparations and wetting pressures. It is shown that the collapse potential for a particular density and wetting pressure decreases generally with decrease in initial matric suction. An empirical equation to predict collapse potential of South Australian silty glacial sand was proposed using appropriate parameters. The equation was found to estimate collapse better than that of existing empirical equations.