Effects of stress conditions on B-value measurement

The B-value, measured after setting up a specimen for triaxial testing, is used for evaluating the degree of saturation of a specimen. However, the stress conditions used when measuring the B-value have not been standardized. Although some experimental approaches have been pursued, no detailed analyses have evaluated the effects of the measurement conditions on the B-value results. In this study, the B-values of nearly saturated specimens under various stress conditions were investigated, using a smart triaxial test apparatus capable of elaborate stress control, and comparisons among measurement results were conducted. Moreover, by applying Henry׳s law, which governs the dissolution of the gas phase into the liquid phase, to an existing constitutive model for unsaturated soil, a new soil model was proposed. This new model accurately represents the behaviors of pore air even under nearly saturated conditions. In addition, the effects of the stress conditions on the B-values were investigated through numerical simulations of B-value measurements.