Nonlinear sound propagation in stressed cemented granular materials is investigated using the split Hopkinson pressure bar (SHPB) system, via frequency spectra analysis. The sandstone is selected for performing the experimental investigation. The sound velocity is deduced from experimental measurement of amplitude ratio of incident to transmitted waves, showing a power (1/6) law scaling with confining pressure, confirming the applicability of Hertzian nonlinear elasticity on cemented granular materials. Analysis on the measured magnitude of second-harmonic gives the coefficient of nonlinearity whose order of magnitude is consistent with that deduced from acoustoelastic method with a relationship 𝛽AE ≈ (1.5 ∼ 4.5)𝛽WM. The transmitted wave amplitude is also analyzed by applying repetitive impact load, demonstrating that relatively high intensity incident wave as well as lower confining pressure induces intensive weakening of the rocks.
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