Abstract:  The bender element is a commonly used method for testing small strain dynamic parameters of soil. However, when using bender element for testing, the waveform, frequency, peak value, and sample size can have a certain impact on the determination of the travel time of the wave in soil. At present, the influence of input wave on the travel time of output signal is mostly studid from the aspect of the frequency of input wave, but the the impact of the input wave peak and input waveform on the output signal is soldom studied. Therefore, in this paper the small strain dynamic parameters of dry Fujian standard sand were studied by bender element, and the effects of parameters such as input frequency, input wave peak, input waveform, relative density, and confining pressure on the constrained modulus, shear modulus, and Poisson’s ratio were analyzed. The results show that the input frequency has a significant effect on the travel time of S-wave(shear wave), and basically has no effect on P-wave(primary wave). The magnitude of the input wave peak has no effect on the travel time of S-wave or P-wave discrimination. The input waveform has a significant effect on the travel time of the S-wave or P-wave. The constrained modulus, shear modulus, and Poisson’s ratio of soil vary exponentially with the increase of confining pressure and pore ratio. Based on the small strain modulus prediction model proposed by Hardin, a three-dimensional model formula considering the coupling effect of confining pressure and pore ratio was fitted, which can provide certain reference for the estimation of constrained modulus, shear modulus, and Poisson’s ratio in practical engineering.

Key words:  , bender elements, Fujian standard sand, constrained modulus, shear modulus, Poisson’s ratio ,