ABSTRACT
A series of cyclic triaxial tests were performed using two types of well-graded gravels of crushed aggregate from granite (Uc = 53 with Dmax = 31.5 mm; and Uc = 28 with Dmax = 12.5 mm) from Portugal at different stress states along isotropic and anisotropic stress paths (K= Δσv/Δσh= 1 to 16) and in triaxial compression at a constant σh. Axial and lateral strains were measured locally on-sample. Effects of stress state and loading history, as well as the type of material, on the elastic stifthess defined for a strain amplitude of the order of 0.001 % were evaluated. The vertical elastic Young’s modulus Ev was essentially a unique function of the vertical (axial) stress, while it was rather independent of the horizontal (lateral) stress. This results is consistent with those from previous similar tests on sands and gravels. The effects of 21,000 cycles of a relatively large amplitude of deviator stress, causing relatively large strain amplitudes, on the elastic Young’s modulus were found negligible, while a triaxial extension loading seems to decrease the vertical elastic Young’s modulus. Despite a similar void ratio, the Ev values of the two similar gravels having different grading characteristics differed by a factor of more than two under otherwise the same test conditions.
