三轴剪切下珊瑚砂颗粒破碎规律及强度特征

珊瑚砂广泛分布于我国南海岛礁,其性质与普通砂有明显的差异,主要体现在颗粒具有显著的破碎特征。为进一步研究珊瑚砂的破碎特征和破碎对其强度特征的影响规律,本研究通过控制相对密实度、含水率和围压等多种初始条件展开三轴固结排水(CD)的剪切试验。结果表明:珊瑚砂颗粒破碎会根据相对密实度以及围压的逐渐增大而增大,随着含水率的增大而先增大后减小,但是随围压的增大,颗粒的破碎不会无限制增大,当到达一定程度时会逐渐趋于停止;在相对密实度保持一定时,珊瑚砂的内摩擦角会依据含水率的增大而先增大后减小。珊瑚砂大颗粒破碎形成小颗粒并嵌固在孔隙中,大小颗粒之间的相互作用及级配趋于良好,颗粒的破碎一定程度上增大了珊瑚砂的强度。此试验成果可以为岛礁珊瑚砂工程建设提供参数依据,为深入研究珊瑚砂颗粒破碎的理论提供借鉴。

Particles Breaking Regularity and Strength Characteristics of Coral Sand under Triaxial Shear Conditions

Coral sand is widely distributed in the islands and reefs of South China Sea, and its properties are significantly different from those of ordinary sand, mainly reflected in the significant fragmentation of the particles. In order to further study the crushing characteristics of coral sand and the effect of crushing on its strength characteristics, the triaxial consolidation drainage (CD) shear test was carried out by controlling various initial conditions such as relative compactness, water content, and confining pressure. The results show that the crushing of coral sand particles will increase according to the relative density and the increasing confining pressure. With the increase of water content, the crushing will first increase and then decrease. However, with the increase of confining pressure, the crushing of coral sand particles will not increase indefinitely. When the relative compactness remains constant, the internal friction Angle of coral sand will increase first and then decrease according to the increase of water content. The large particles of coral sand are broken to form small particles and embedded in the pores. The interaction and gradation between large and small particles tend to be good, and the crushing of particles increases the strength of coral sand to some extent. The experimental results can provide a parameter basis for the construction of reef coral sand projects and a reference for the in-depth study of the theory of coral sand particle breakage.