Analytical and experimental studies on biot flow-induced damping in saturated soil specimens in resonant column tests

This paper presents an analytical and experimental investigation of Biot flow-induced damping in saturated soil specimens in resonant column tests. In the analytical investigation, the solid skeleton is treated as poroviscoelastic (i.e., equivalent linear). Biot flow-induced damping is evaluated based on the half-power bandwidth and free vibration decay methods. These solutions are found to be generally consistent with a closed-form analytical solution readily available in the literature. The solutions indicate that maximum values of Biot flow-induced damping occur in coarse sand and gravel, and can be practically neglected for less permeable soils (e.g., fine sand, silt, and clay). The solutions also indicate that Biot flow-induced damping increases as porosity increases, and decreases considerably as the ratio of the mass polar moment of inertia of the loading system to the specimen increases. In the experimental investigation, resonant column tests were conducted on granular specimens in dry and saturated conditions to quantify Biot flow-induced damping and compare with the analytical solutions. The test results are found to be in general agreement with the analytical solutions within the measurement accuracy of the device used in this study.