Study on the inhibitory effect of rubber on particle breakage and the impact on the volumetric deformation of calcareous sand under different loading modes

Considering economic and environmental factors, incorporating rubber into calcareous sand as a backfill material in marine engineering construction is a favorable approach. The research on rubber -modified sand has been extensive in the past, but it has not been fully understood. There is a need for a comparative study between impact loads and static loads. This study employs cyclic impact breakage tests and triaxial compression breakage tests to investigate the inhibitory influence of rubber on particle breakage and the Impact on the Volumetric Deformation of calcareous sand under distinct loading conditions. The experimental results indicate that under impact loading, as the impact energy increases, the relative breakage rate of calcareous sand increases, but the rate of increase gradually decreases. The addition of rubber up to a content of 10% notably suppresses calcareous sand breakage, while the impact of a rubber content between 10% and 20% on breakage is weaker. A higher rubber content results in a reduced sensitivity of sample breakage, which may be related to the coordination number of the calcareous sand and rubber. Under the final impact energy, a lower rubber content leads to a greater volumetric deformation of samples, while this trend reverses during the early loading stages due to the superior deformability of rubber. Furthermore, the dependency of calcareous sand particle breakage on volumetric deformation gradually decreases with increasing rubber content. Unlike under impact loading, under triaxial compression loading, along with the increase in input energy, the relative breakage rate of calcareous sand shows continuous growth, and its rate of increase progressively intensifies, which is related to the decreasing degree of participation of rubber. During the consolidation deformation phase, a linear correlation emerges between the input energy and deformation for rubber -modified samples, referred to as the consolidation deformation curve. In the compression phase, a positive linear correlation between volumetric deformation and input energy is observed. The findings of this study offer certain theoretical guidance for understanding the breakage and deformation patterns of rubber -modified calcareous sand in engineering applications.