Volume 30, Issue 6 (November 2007)
Shear Strength Estimation of Sandy Soils Using Shear Wave Velocity
Typically, shear strength is associated with large strain phenomena, while shear wave propagation is associated with small strain phenomena. Yet, the effective stress and void ratio, both key determinants of sandy soil shear strength, are also the primary factors affecting shear wave velocity. This study presents a shear wave velocity-void ratio-shear strength correlation through experimental tests. Natural sands taken from various reclaimed or recently deposited sandy fields are used for reconstituting specimens at different void ratios in an oedometer cell. Shear wave velocities are measured while changing the state of the stress in the cell for each specimen prepared at a specific void ratio. The relationship between shear wave velocity and vertical effective stress is found at extreme values of void ratios (emin and emax). Direct shear tests are also performed on specimens with various void ratios. Experimental results show that the internal friction angle of each sand type increases with decreasing void ratio, rendering a unique relationship between friction angle and void ratio. Finally, a procedure is suggested to evaluate the in-situ shear strengths of a sandy soil based on in-situ shear wave velocities. Results show that the suggested method effectively estimates in-situ shear strength.