Abstract: The pore structure and water retention capacity of soils are significantly affected by the cyclic drying-wetting and stress history. To further study the coupling actions of the two factors, water content variation tests were carried out following two different loading paths, i.e., the drying-wetting cycles after vertical consolidation, and the vertical loading-unloading cycles after the air-dried process. The variation tendencies of the water retention capacity and deformation behaviors of soil specimens were explored. The results indicated that the water retention capacity of soil during drying process is significantly different from that during wetting process, and the difference gap tends to decrease with increasing the consolidation pressure. With the increase in the number of drying-wetting cycles, the air-entry values increase while the slopes of the drying phase and wetting phase decrease. These changing tendencies are less significant upon more drying-wetting cycles. As for the soil specimens with different degrees of saturation, with the increase in the pore air pressure, the pre-consolidation pressures of soils are augmented, whereas the areas of hysteresis loop decrease, and hence resulting in decrease in the water retention capacities and deformation. The identical stress states can be reached from two different paths. It was found that the volumetric shrinkage is higher for the soil specimens following the path of drying process after consolidation, and the water retention capacities are lower for the soil specimens following the path of loading after air-dried process.

Key words: cyclic drying-wetting, repeated loading-unloading, coupling action, water retention capacity, deformation behavio