海洋珊瑚黏土岩土特性的室内研究

Laboratory study on geotechnical characteristics of marine coral clay

吹填珊瑚黏土是一种新型黏土,是珊瑚岛礁吹填过程中分选形成的特殊黏土。新的水力吹填工程珊瑚礁地基,包括珊瑚砂、淤泥和黏土。粒径小于75μm的且含量占50%以上这部分形成黏土。作为一种新型黏土,其岩土工程性质在以往的研究中鲜有报道。本文通过一系列室内试验,对其力学性能、微观结构和矿物组成进行了综合研究。结果表明:珊瑚黏土是一种高孔率、高饱和度的低液限黏土。珊瑚黏土的矿物成分为方解石和文石,化学成分为碳酸钙。孔隙比对珊瑚黏土的压缩性能有显著影响。随着孔隙比的增大,压缩系数a_(1-2)和压缩指数C_(c)逐渐增大,压缩模量Es逐渐减小。珊瑚黏土的不排水应力−应变曲线表现出应变软化特性,峰值强度和残余强度与围压呈线性正相关。在试验围压范围内,峰值强度与残余强度的折减为26.8%~36.1%。

The hydraulic reclamation coral clay is a new type of clay,formed during the sorting process of coral island reef reclamation.The foundation of the hydraulic reclamation coral reef consists of coral sand,silt,and clay.The part of the particles with particle size less than 0.075 mm contain more than 50%forms clay.As a new type of clay,the geotechnical properties were rarely reported in previous studies.In this paper,the physical and mechanical properties,microstructure and mineral composition were comprehensively researched by a series of laboratory tests.The results show that coral clay is a low liquid limit clay with high pore ratio and high saturation.From the aspect of mineral compositions,the coral clay studied consists of calcite and aragonite,while the chemical composition of it is calcium carbonate.The void ratio has a significant effect on the compressive properties of coral clay.With the increase of the void ratio,the compression coefficient a_(1-2) and compression index C_(c) gradually increase,and the compression modulus Es gradually decreases.The undrained stress−strain curve of coral clay shows a strain-softening behavior,and the peak strength and residual strength are positively linear correlated with confining pressure.