Experimental Study on the Mechanical Strength, Deformation Behavior and Infiltration Characteristics of Coral Sand

In this investigation, coral sand is presented as a sustainable substitute for conventional river and machine-manufactured sand. This study comprehensively investigated the macro-scale strength, deformation, and permeability characteristics of coral sand, alongside analyzing the mechanical behavior, deformation, and permeability under various conditions and in relation to distinct particle characteristics. It revealed that coral sand primarily consists of biotite and high-Mg calcite, featuring abundant internal pore space. Its compressive properties resemble clayey soils, displaying minimal unloading rebound and predominant plastic deformation during compression. In direct shear tests, the stress–strain relationship follows an approximate hyperbola, with no pronounced strain softening. Describing particle fragmentation in the process proves challenging, making indicators like internal friction angle less applicable in engineering. Triaxial tests indicate a rapid initial bias stress increase, followed by a gradual decrease post-stress peak, suggesting a strain softening phenomenon. As surrounding pressure rises, the axial strain needed to reach peak strength also increases. The permeability coefficient of coral sand correlates linearly with pore ratio increase, represented by 10e. The complex interaction of multiple factors influences the strength, deformation, and permeability of coral sand blown fill mixes, with specimen porosity having the greatest impact. The design and construction of high-weight foundation elements in coral sand blown fill projects should consider porosity effects.