Vertical Stress Effects on Soil-Water Characteristics of Fly Ash

In this paper, a SWC-150 Fredlund soil water characteristic device is used to test the soil-water characteristic curve of fly ash to investigate the influence of high vertical stress, and the fitting parameters of the Fredlund & Xing tri-parameter equation are determined to discuss the effects of stress. The test results show that the effects of stress change on the air-entry value can be neglected when the vertical stress is high, while the hydraulic hysteresis loops decrease significantly with increasing vertical stress. Furthermore, compared with the specimen without stress, the specimen with vertical stress exhibits a slightly lower residual water content, a smaller hysteresis loop, and a considerable reduction in the slope of the transition segment of the wetting curves when they have the same dry densities before drying. The fitting results indicate that when the vertical stress is quite high, the variations in parameters that relate to the air-entry value and residual water content conditions with increasing stress are not obvious in the drying curves.