Experimental study on drying shrinkage of unsaturated compacted soils

Compression of soils could be caused by the increase of both matric suction and net mean stress.The empirical relationship between the matric suction and the void ratio on drying path was established for four types of soils including sand,silt,clay and soft clay by utilizing the shrinkage curves and the soil-water characteristic curves determined through experimental tests.It was indicated that during the process of drying,the soil samples continuously shrunk with the increase of matric suction.That is,Once the matric suction increased to a given value when the increase of suction would display no obvious effect on the shrinkage deformation of the soil samples and it was defined as the shrinkage limit suction ss.The values of ss were dependent on the plasticity index of soil.The process of shrinkage of soil was divided by the yielding suction s0 and the shrinkage limit suction ss into three stages,i.e.,elastic stage,elasto-plastic stage and stage of shrinkage limit.Moreover,in the process of drying-shrinkage of soil samples,the shrinkage of the soil samples was almost fulfilled when the degree of the saturation of soil samples decreased to 90% and the void ratio of the soil samples almost kept unchanged while the degree saturation of soil was reduced to 70%.