钙质土颗粒表面微形貌特征及持水特性研究

In recent years, Hydraulic Fill Coral Sands Land is a strong measure to implement the strategy of ocean power and defend the territorial sovereignty and maritime rights in the South China Sea. The surface on reclaimed soil particles is rich in half open mesoporous. The water retaining capacity of calcareous soil can be as much as 20- 24%, far higher of silica sand about 4%, which has crucial significance to the reef vegetation system development. However, there are few concerns payed on the high water-holding capacity characteristics in research fields today. Therefore, this project is to bridge the soil water-holding performance at macroscopic and the surface physical-chemical properties at nanoscale with the particle surface micro-topography of submicron scale and to consider it as an effective analysis tool meanwhile. The natural desalting process of the hydraulic fill coral sands land is considered in this project. Particle surface micro-topography will be acquired by scanning electron microscopy (SEM) test and nitrogen adsorption test. A scientific systematic description methods for characterization of micro particle morphology indexes will also be constructed. After that, the relationship between the particle surface micro-topography characteristics and the solution concentration will be clarified. The soil-water characteristic curve (SWCC) of Coral reef calcareous soil over a wide range of suction was determined based on the pressure plate and vapor equilibrium techniques. The soil samples were prepared by saturating the soil with solutions with different concentrations. The effect of pore solution concentration on the SWCC was analyzed. Basis on it, and refers to the related Advance on surface physical chemistry. The mechanism of calcareous soil moisture characteristic will be comprehensively discussed in the view of particles micro-topography. Engineering strategies will be given for improving the water-holding capacity of calcareous soil. This project will have significant theoretical and application value for the ecological process on hydraulic fill coral sands land of South China Sea, protecting the marine rights and interests of China and hoping our marine power dreams come true soon.

吹填造岛工程的实施是捍卫我国领土主权和海洋权益的强力举措。吹填钙质土颗粒表面富含数十纳米量级的半开放介孔，持水度高达20~24%，远高于硅质砂的约4%，对岛礁植被系统发育具有关键性意义。但学界对钙质土的高持水能力尚缺少关注。为此，本项目以亚微米尺度的颗粒表面微形貌作为连接亚纳米尺度颗粒表面物理化学特性与宏观土体持水性能的桥梁和分析工具，考虑岛礁自然淋滤淡化过程，通过扫描电镜试验、氮气吸附试验获取颗粒表面微观形貌并构建体系化的描述方法科学表征颗粒微形貌特征与溶液浓度之间的关系；开展压力板试验和蒸汽平衡法试验探究钙质土持水特性，构建土-水特征曲线模型并研究钙质土持水特性与溶液浓度之间的平衡机制；在此基础上借鉴表面物理化学相关研究成果，综合探讨钙质土持水特性的颗粒微形貌机理，给出提升钙质土地基持水能力的工程策略，为绿色生态岛礁战略的实施及可持续发展提供理论与技术保障，具有显著的理论意义和应用价值

珊瑚钙质土颗粒表面富含数十纳米孔径的半开放介孔，持水度远高于硅质砂，对岛礁植被系统发育具有重要意义。本项目以亚微米尺度的颗粒表面微形貌为切入点，研究工作聚焦钙质土持水特性问题。开展了扫描电镜试验、氮气吸附试验获取颗粒表面微观形貌，初步构建了体系化的描述方法科学表征颗粒微形貌特征；开展了压力板试验探究钙质土持水特性；此外，拓展探索了基于钙质砂土干湿循环的海滩岩快速胶结成岩物理过程机理模型。项目研究成果可助益绿色、生态岛礁的可持续发展，也为后续开展岛礁海岸海滩岩自然胶结成岩的机理研究和过程干预加速研究提供了新视角和初步理论基础。