Shear wave speed dispersion and attenuation in granular marine sediments

Abstract

The reported compressional wave speed dispersion and attenuation could be explained by a modified gap stiffness model incorporated into the Biot model (the BIMGS model). In contrast, shear wave speed dispersion and attenuation have not been investigated in detail. No measurements of shear wave speed dispersion have been reported, and only Brunson's data provide the frequency characteristics of shear wave attenuation. In this study, Brunson's attenuation measurements are compared to predictions using the Biot-Stoll model and the BIMGS model. It is shown that the BIMGS model accurately predicts the frequency dependence of shear wave attenuation. Then, the shear wave speed dispersion and attenuation in water-saturated silica sand are measured in the frequency range of 4-20 kHz. The vertical stress applied to the sample is 17.6 kPa. The temperature of the sample is set to be 5 °C, 20 °C, and 35 °C in order to change the relaxation frequency in the BIMGS model. The measured results are compared with those calculated using the Biot-Stoll model and the BIMGS model. It is shown that the shear wave speed dispersion and attenuation are predicted accurately by using the BIMGS model.

Numerical and Experimental Study of Wave Propagation in Water-Saturated Granular Media Using Effective Method Theories and a Full-Wave Numerical Simulation

“…The Biot-Stoll model is widely used and a useful tool to analyze the acoustic characteristics of water-saturated granular media. Kimura et al summarized the characteristics of the Biot-Stoll model and reported some comparisons between analytical and experimental results [11], [32], [33]. Let us briefly recall the main characteristics of the Biot-Stoll model (more detailed information on the Biot-Stoll model can be found in [3], [7], [8], [17], [18], and [32]).…”

Grain-size dependence of shear wave speed dispersion and attenuation in granular marine sediments

“…A heuristic correction factor for attenuation, C a , was taken to fit the measured values of the shear wave attenuation to the calculated values. 4 The factor is defined as follows:…”

“…The measurement method is almost the same as that described in Ref. 4. The sample was placed in a cylindrical acrylic vessel with an inner diameter of 43 mm.…”

“…Recently, the author measured the temperature dependence of shear wave speed dispersion and attenuation in water-saturated silica sand which grain size is 0.113 mm in the frequency range of 4-20 kHz, and showed that the measured results can be predicted by using a gap stiffness model incorporated into the Biot model (the BIMGS model). 4 The author has also derived the relationship between the aspect ratio in the BIMGS model and the grain size / (¼ Àlog 2 d, d in mm), for both compressional and shear waves. 4 In this study, the grain-size dependence of shear wave speed dispersion and attenuation in four kinds of water-saturated silica sands with different grain sizes are measured.…”

“…4 The author has also derived the relationship between the aspect ratio in the BIMGS model and the grain size / (¼ Àlog 2 d, d in mm), for both compressional and shear waves. 4 In this study, the grain-size dependence of shear wave speed dispersion and attenuation in four kinds of water-saturated silica sands with different grain sizes are measured. The measured results are compared with the calculated results using the BIMGS model, and the grain-size dependence of the shear wave speed dispersion and attenuation are investigated.…”