Soil-water retention behavior of compacted soil with different densities over a wide suction range and its prediction

To investigate the soil-water retention behavior of a clayey silt over a wide suction range, the suction is imposed on clayey silt specimens using the pressure plate method and vapor equilibrium technique with saturated salt solutions. The test results show that the soil-water retention curves (SWRCs) in terms of gravimetric water content versus suction relation over a wide suction range are independent of the initial dry density or void ratio when the suction is higher than a specific value, which can be determined by results of the mercury intrusion porosimetry test. When the SWRC is expressed in terms of degree of saturation versus suction relation over a wide suction range, the influence of dry density or void ratio is highlighted. This behavior can be explained by the features of the pore-size distribution. Residual suction and water content of specimens with different void ratios are almost the same and the air entry values of specimens show a linear relationship in the plane of water content versus suction with the logarithmic coordinate. Finally, the Fredlund and Xing SWRC equation is used to uniformly describe the SWRCs of specimens with different void ratios by taking above features of the SWRC into consideration, and the predicted results are compared well with measured values.