Frequency effect on mechanical properties of calcareous sand under cyclic traffic loading

Calcareous sand is an essential material for building airports in the South China Sea. Frequency plays an important factor in the dynamic properties of calcareous sand. However, most of the related studies adopted cyclic triaxial tests and impractical loading paths and showed contradictory results. This paper summarizes the potential reasons for the conflicting conclusions, and analyses the mechanical behavior of three types of samples, including unstable, metastable, and stable situations under cyclic traffic loading with Hollow Cylinder Appa-ratus. This research proposed a new method to clarify the sample stability under cyclic stress ratios with different frequencies and found that resilient porewater pressure (pwpr) can be more appropriate than other commonly used parameters e.g. strain, porewater pressure, and dissipation energy. The pwpr also correlates with the particle morphology of calcareous sand, which with more irregular morphology leads to greater sensitivity to loading changes. The results indicate that higher frequency stabilizes the samples regardless of cyclic stress ratios. Considering the frequency effect, the paper gives related functions and simulates cumulative axial plastic strain variations and elastic modulus against cycle numbers for stable samples.

Automated summary

This study conducted experiments on calcareous sand, which is essential for building airports in the South China Sea, and found that frequency has a significant impact on the dynamic properties of calcareous sand. Previous studies have shown contradictory results, and this paper summarizes the potential reasons for these conflicting conclusions. Through a series of experiments, the mechanical behavior of three types of samples under different frequencies was analyzed. Resilient porewater pressure was found to be a more accurate parameter to describe the sample stability compared to other commonly used parameters, and it was found to be related to the particle morphology of the calcareous sand. The results indicate that higher frequency stabilizes the samples' mechanical properties.