吹填珊瑚岛礁钙质软泥的渗透特性试验研究

钙质软泥作为吹填珊瑚地基土的一部分,其渗透特性对于岛礁工程的建设具有重要意义。基于GDSPERM全自动环境岩土渗透试验系统对南海某岛礁钙质软泥进行系列固结渗透联合试验,探究孔隙比、固结历史、固结压力、水力梯度和孔隙液离子浓度对钙质软泥渗透特性的影响,并对钙质软泥孔隙比与渗透系数之间的非线性关系进行拟合分析,得出钙质软泥的系列渗透规律。结果表明：钙质软泥的渗透系数约为10^-6 cm/s,且不随水力梯度的变化而变化,存在初始水力梯度;固结历史对钙质软泥渗透性有较大影响,在孔隙比相同的条件下,未经固结的土样呈现出更低的渗透性能;钙质软泥的渗透系数随固结压力的增大而减小,减小幅度不超过一个数量级;随着孔隙比的增大,钙质软泥的渗透系数也相应增大,两者呈非线性关系,"lgk_v（1+e）]-lg e"模型拟合效果较好,为适用于钙质软泥的最优非线性渗透模型;钙质软泥的渗透系数随孔隙液NaCl浓度的增大而减小。

Experimental study on permeability characteristics of hydraulic reclamation calcareous clay in coral reef island

Calcareous clay is a kind of hydraulic reclamation coral foundation soil, whose permeability is of great significance for the construction of coral reef island projects. Based on the GDSPERM automatic environmental geotechnical permeability test system, a series of consolidation and permeability joint tests of calcareous clay of an reef island in the South China Sea were carried out, and the effects of void ratio, consolidation history, consolidation pressure, hydraulic gradient and pore fluid ion concentration on the permeability characteristics of calcareous clay were studied. The fitting analysis of the nonlinear relationship between the void ratio and the permeability coefficient of the calcareous clay was carried out, and a series of permeability laws of the calcareous clay have been summarized. The results show that the permeability coefficient of calcareous clay is about 10^-6 cm/s, and it does not change with the change of hydraulic gradient. There is an initial hydraulic gradient in its permeation; The consolidation history has a great influence on the permeability of calcareous clay. Under the same void ratio, unconsolidated soil samples show lower permeability; The permeability coefficient of calcareous clay decreases with the increase of consolidation pressure, and the decrease does not exceed an order of magnitude; As the void ratio increases, the permeability coefficient of the calcareous clay increases accordingly, and the relationship between the two is nonlinear. The "lgk_v(1+e)]-lg e" model has a better fitting effect, which is considered to be the optimal nonlinear permeability model for calcareous clay; The permeability coefficient of calcareous clay decreases with the increase of NaCl concentration of pore solution.