关键词: 砂土, 剪切模量, 侧限模量, 泊松比, 弯曲-伸展元, 共振柱

Abstract: The compression wave (P-wave) and shear wave (S-wave) in dry sand are measured simultaneously by a bender-extender element incorporated in a resonant column apparatus. The characteristics of the output P-wave and S-wave signals are analyzed; and the effects of the input signal frequency, soil density and effective confining pressure on the signal characteristics are investigated. According to the wave propagation theory and measured S-wave and P-wave velocity, the elastic properties of the dry sand are calculated, including shear modulus, constrained modulus and Poisson’s ratio. The results indicate that to some extend the frequency of the output signal increases with increasing input frequency, soil density and effective confining pressure. Compared with S-wave, it is easier to determine the P-wave travel time and thus the wave velocity. The elastic modulus of the soil increases with increasing density and effective confining pressure, especially the shear modulus. The Poisson’s ratio decreases with increasing density and confining pressure, instead of a constant. Attempt is also made to estimate the Poisson’s ratio based on shear modulus considering the convenience of application in the practical engineering.

Key words: sand, shear modulus, constrained modulus, bender-extender element, resonant column