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–γ and d–γ curves and the reference strain (γ r). a total of 45 g–γ and d–γ 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 600 kpa). comparison of the g max results of the resonant column and bender element tests was also carried out. the desired excitation frequencies and ratios λ/d 50 and d/λ (where λ 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 γ r. the results of the tests were used to validate previous models and empirical curves.