Particle size and confining-pressure effects of shear characteristics of coral sand: an experimental study

• Published in: Bulletin of engineering geology and the environment 2022-03, Vol.81 (3), Article 97
• Main Authors: Wang, Xing, Wang, Xinzhi, Shen, Jianhua, Zhu, Changqi
• Format: Article
• Language: English
• Subjects: Earth and Environmental Science; Earth Sciences; Foundations; Geoecology/Natural Processes; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Nature Conservation; Original Paper
• ISSN: 1435-9529; 1435-9537
• DOI: 10.1007/s10064-022-02599-x

Particle size and confining pressure are important factors that influence the shear characteristics of coral sand. In this study, multiple consolidated-drained triaxial shear tests were conducted under varying conditions, to explore the effect of particle size and confining pressure on the shear characteristics of coral sand, in terms of critical confining pressure and shear strength, respectively. Particle survival rates of coral sand under different conditions were compared. It was found that (i) the stress-softening coefficient and dilatancy coefficient had a semilogarithmic linear relationship with effective confining pressure. With an increase in effective confining pressure, the strain-softening and dilatancy of the coral sand weakened gradually. Compared with small-particle coral sand, the strain-softening and dilatancy of large-particle coral sand attenuated at a greater rate, and the mode conversion for deformation curves occurred prior to that for the strength curves. (ii) Under the same relative density, because of differences in the void ratio of coral sand with different particle sizes, the shear strength deviations increased gradually with an increase in effective confining pressure. For this reason, the internal friction angle of coral sand decreased with an increase in particle size, whereas its apparent cohesion presented an opposite trend. (iii) Under the combined action of single-particle crushing strength and particle coordination number, coarse coral sand ( D  = 1.0–2.0 mm) showed the largest amount of particle breakage.