Statically and Dynamically Measured Poisson's Ratio of Granular Soils on Triaxial Laboratory Specimens

Poisson's ratios and small-strain stiffnesses of three kinds of granular materials fine, medium coarse, and coarse sands were evaluated in the laboratory. Both axial and radial strains of cylindrical triaxial specimens were measured with a local deformation transducer and clip gauges. Small-strain (approximate to 0.001 %) cyclic loadings were applied in the vertical direction at several isotropic stress states. We determined Poisson's ratio statically based on the local strain variations during the cyclic loadings; we also investigated the stiffness in parallel. In conjunction with static measurements, elastic waves were propagated. By utilizing the disk transducer method, we were able to measure both compressional and shear waves in a single specimen under identical stress states. Based on the received wave velocities of compressional and shear waves, we were able to evaluate both Poisson's ratio and the small-strain stiffness dynamically. We then compared elastic parameters evaluated both statically and dynamically for the geo-materials.