关键词: 钙质砂, 冲击荷载, 体积变化, 破碎率, 分形维数

Abstract: Particle breakage is a problem often encountered in piling, compaction, rolling and other reinforcements of calcareous sand foundation, imposing a significant impact on the physical and mechanical properties of sand particles. This study conducts impact loading tests on calcareous sand, and compares it to the quartz sand with the same grading. Results show that attrition and abrasion are the major patterns of particle breakage in the initial loading stage of the two types of sand, while in the later stage, only a slight abrasion can be observed for quartz sand but calcareous sand still has obvious attrition. Fractal dimension analysis reveals that in low cumulative energy, calcareous sand features a dimension larger than quartz sand; but with the energy increasing, its dimension will be gradually exceeded by the latter. The fitting curves of fractal dimension versus breakage rate of the two sands are linear. During an impact loading, the ratio of the volume change over the breakage rate of quartz sand reaches a steady state that develops into fractal distributions. Under the conditions of this test, the volume of both sands and the numerical change in their breaking rate vary with energy input.

Key words: calcareous sand, impact loading, volume change, breakage rate, fractal dimension