Stiffness Degradation and Damping Ratio of Sand-Gravel Mixtures Under Saturated State

The aim of this research was to explain the effects of gravel content using the intergrain state concept, relative density and confining pressure on G(max), G/G(max)- and D- curves and the reference strain ((r)). A total of 45 G- and D- curves derived from resonant column testing and cyclic triaxial testing along with S-wave velocity measurements obtained using the bender element technique were assessed. The test specimens were prepared with different gravel contents (0, 30, 50, 75 and 100%) under different relative densities (10, 30 and 60%) and mean effective confining pressures (100, 300 and 600kPa). Comparison of the G(max) results of the resonant column and bender element tests was also carried out. The desired excitation frequencies and ratios /D-50 and d/ (where is wavelength, d is transmission path length and D-50 is average particle size) were determined based on the bender element tests results. The test results were used to evaluate the empirical equation for prediction of G(max) and to develop a new prediction equation with which to estimate (r). The results of the tests were used to validate previous models and empirical curves.