Effect of gradation and relative density on shear strength of coral sand.

Due to the wide particle size distribution of coral sand, There are significant differences in mechanical behaviour of coral sand with different particle size distribution. It is of great significance to propose a quantitative analysis method for mechanical properties considering the effect of gradation. In this study, 27 groups of coral sand specimens with particle size ranging from 5 mm to 0.125 mm were prepared. The consolidated undrained (CU) triaxial shear tests were carried out and the influence of gradation and relative density on the shear characteristic were discussed. The grading and relative density of coral sand are controlled by the median particle size (d50) and relative density (Dr), The results show that the peak deviator stress decreased, and the effective internal friction angle first increased and then decreased with the increase of d50. Both the peak deviator stress and effective internal friction angle of coral sand increase with the relative density. A parabolic relationship was founded between the effect internal friction and d50 as Dr was constant. The effective friction angle peaked when d50 was 2 mm. Finally, a calculation method of shear strength parameter considering the gradation and relative density of coral sand was proposed. [ABSTRACT FROM AUTHOR]