Particle shape influence on the deformation resistance of carbonate sands under drained condition

• Published in: Soil dynamics and earthquake engineering (1984) 2021-05, Vol.144, p.106688, Article 106688
• Main Authors: Rui, Shengjie, Guo, Zhen, Si, Tongling, Zhou, Wenjie, Zha, Xing
• Format: Article
• Language: English
• Subjects: Carbonate sand; Carbonates; Contraction; Cyclic testing; Cyclic tests; Deformation effects; Deformation resistance; Drained condition; Dynamic loads; Irregular particles; Particle breakage; Particle shape; Phase transitions; Porosity; Sand; Shear strain; Shear strength; Stress ratio; Surface grinding
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2021.106688

The carbonate sand has high porosity and irregular particle shape compared with the quartz sand. Under dynamic loads, the carbonate sand perhaps experiences drained or partial drained shear, and the contribution of particle shape to its deformation resistance was still unrevealed. In this paper, particle shapes of five samples were first quantitively evaluated. Then, monotonic and cyclic tests under drained condition were carried out based on the simple shear apparatus. The particle size and shape were quantitively measured after the tests, and the particle breakage degree and its breakage mode were discussed. It is found that before phase transformation points (PT points), the irregular particles mobilize greater shear resistance. The particle breakage reduces the deformation resistance after the PT point due to its depression effect on the volume shear dilation. In cyclic shear, irregular particles have larger volume contraction due to the particle breakage, and the surface grinding is the major breakage mode. Under the same cyclic stress ratio (CSR), the irregular particles show smaller shear strain amplitudes, indicating that the irregular particles have stronger resistance to deformation. It is also found that the particle shape mainly influences the deformation resistance when the overall regularity (OR) is less than 0.8. •The particle shape influence of carbonate sands on the shear resistance in drained simple shear tests is investigated.•The particle size and shape are quantified to assess the particle breakage degree.•The relationship between the cyclic shear ratio and the final P–P strain is established.•It is found that the irregular sand particles need more cycles to reach the stable strain.