Evaluation of the damping ratio of soils in a resonant column using different methods

This paper addresses the differences between two approaches of damping estimation in the resonant column testing: Steady-State Vibration (SSV) and Free Vibration Decay (FVD) method, at small (<0.005%) to medium (0.07%) strain range. The tests were conducted on “two types of reconstituted sands” and “two types of clayey soils” at different relative densities and confining pressures. The test results suggested to use the SSV method in small strain damping measurement and the FVD method (two or three successive cycles) in medium strain damping measurement. A systematic decrease in the damping with the increasing number of cycles was observed up to a certain strain level in the FVD method. Furthermore, the effects of relative density, confining pressures, soil types on the damping ratio derived from the two methods for the chosen soils were studied. The results showed that the damping ratio of clayey soils exhibits a little higher value than those of sandy soils.