Abstract: Analysis of the effects of sizes, shapes and wetting condition on crushing strength and modes of calcareous sand can be accomplished using a statistical method by subjecting particles with different sizes and shapes to single particle crushing tests through automatically uniaxial loading system and the crushing process, and modes of particles were observed and recorded with the help of microscopic probe. In addition, the micro-uniaxial loading device supported by in-situ X-ray μCT scan was used to scan the crushing process of two calcareous sand particles with high precision, and the effects of internal pore structure were deeply investigated by image processing and analysis technology. The results show that the characteristic strength of calcareous sand particles is decreased with increasing sizes. While for the particles with similar sizes, the characteristic strength of compact particles is the largest, followed by platy particles and bladed particles, and elongated particles are the least. The crushing process of calcareous sand particles can be summarized as three crack forms and three fracture patterns, which are single crack, cross crack, arch crack and patterns I, II, III, respectively. Finally, analysis results of μCT images show that the cracks caused by particle crushing concentrated mainly in the dense internal pores, which indicated that internal pore structure has an important influence on the crushing behavior of calcareous sand particle.

Key words: calcareous sand, single particle crushing, Weibull distribution, μCT scan, internal pore