Assessment of geomaterial compaction using the pressure-wave fundamental frequency

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Abstract Assessment of geomaterials compaction during layered filling is required for quality control of earthworks such as transportation infrastructure and earth-rock dam construction. This paper presents a new method for non-destructive assessment of geomaterial compaction based on the velocity of vertically propagating pressure- or P-wave evaluated by the detected fundamental frequency and a correlation between the P-wave velocity and the dry density. Field experiments were performed on six types of geomaterials at two dam construction sites. Vertical acceleration data were recorded by piezoelectric accelerometers installed on the drum frame during compaction. The vibration data were processed to identify the fundamental frequency for the evaluation of the P-wave velocity. The P-wave velocity was then correlated to the dry density by linear regression analysis. Results including the fundamental frequency, the P-wave velocity, and the correlations are presented. It was found that the fundamental frequency of the geomaterials can be reliably identified from the vertical acceleration signal, provided a properly configured filter is applied. The P-wave velocity values evaluated based on the fundamental frequency agree well with those assessed based on Young’s modulus, empirical relationships, or field measurement at similar conditions. The fundamental frequency was found to increase consistently with an increasing number of compaction passes, indicating that it can be an excellent indicator of compaction quality. The linear relationships established between the dry density and the P-wave velocity for the six types of geomaterials exhibit higher values of coefficient of determination than existing models based on the peak acceleration, Fourier amplitude, or acoustic wave, indicating that the fundamental frequency-based method can be a more reliable method for assessing geomaterial compaction. The proposed method has the potential to be applied for automatic assessment of geomaterial compaction in the transportation engineering field.