Study on the One-Dimensional Impact Compression Characteristics of Coral Sand Under Conditions of Different Relative Density

Dynamic compression tests under quasi-one-dimensional strain conditions were conducted on coral sand with different relative densities using the Split Hopkinson Pressure Bar (SHPB) apparatus. The experimental results indicate that the stress-strain curves of coral sand exhibit approximately three basic forms, each encompassing three distinct stages: skeletal sliding and yielding, compaction, and unloading. The occurrence of the lock-up phenomenon is jointly influenced by relative density, strain rate, and moisture content. A higher moisture content, lower relative density, and larger strain rate tend to facilitate the occurrence of the lock-up phenomenon. The influence of relative density on the compression behavior of coral sand is comprehensively affected by both the moisture content and the strain rate. Under dry or low-saturation conditions, as the relative density increases, both the tangent modulus in the first stage of the stress-strain curve and the pre-consolidation pressure exhibit enhancements of varying degrees, and the specimens' bearing capacity continues to improve. Conversely, under conditions of high saturation and low strain rate, an increase in relative density results in a decrease in the specimens' bearing capacity. However, as the strain rate progressively increases, the specimens' bearing capacity will improve continuously, swiftly transitioning from a state of decrease to increase, with the magnitude of this improvement continually intensifying.