Effect of initial fabric from sample preparation on the mechanical behaviour of a carbonate sand from the South China Sea

Abstract

Mega reclamation projects have been undertaken on the coral reefs. However, research on the geotechnical properties of the hydraulically filled carbonate sand is limited, and the impact of the initial fabrics from different densification methods on the mechanical behaviour of carbonate sand remains unclear. In this work, a systematic experimental investigation on the effect of initial fabric induced by sample preparation method on the mechanical behaviour of carbonate sand has been performed. Four sample preparation methods, including moist tamping, vibration, dry pluviation and water pluviation were adopted to reconstitute samples with distinct fabrics. It is found that, for a single preparation method, the particle breakage as well as the peak friction angle of carbonate sand is affected by the drainage condition significantly, and both the critical state friction angle (φ'cs) and the compressibility (λ) of carbonate sand are strongly stress dependent. For samples prepared by different methods, an obvious divergence of critical state points can be seen in the specific volume and mean effective stress plane at low stress levels. The dry pluviation samples show the lowest φ'cs and highest λ, due to the highest anisotropy. In contrast, moist tamping samples give the highest φ'cs and lowest λ, due to the most isotropic fabric.