Swelling-Shrinking characteristics and irreversible deformation of expansive soil during wetting-drying cycles

Abstract:

To investigate the Swelling-Shrinking characteristics and irreversible deformation of expansive soil under different pressures and moisture contents, a series of tests under wetting-drying cycles were carried out, and the Swelling-Shrinking characteristics and reasons for fissuring were analyzed from the microcosmic point of view. Based on the above studies, the relationship among heights, relative expansion ratios, relative linear shrinking rates and cycle index under different pressures and moisture contents were explored. Meanwhile, the variation curves of the relative irreversible deformation and accumulative irreversible deformation with increasing cycle index were obtained. The results indicate that the swelling and shrinking are visualized response of the variation of water between soil particles, and also the incentive of fissuring. During the shrinking process, the matric suction increases by the way of maximum limit to prevent moisture content decreasing. There is a linear correlation between the height of test specimen and moisture content under different pressures. The relative expansion ratios will decrease if the cycle index rises, and the same happens with higher pressure. The relative linear shrinking rates will rises firstly and then decreases with the increasing of cycle index. It is shown that the relative expansion ratios and relative linear shrinking rates under different amplitudes of moisture content have a decreasing trend along with the increase of cycle index. The accumulative irreversible deformations increase gradually on the condition that the moisture content is 15% with different pressures, and there will be opposite results with the moisture content of 25%.