基于化学示踪的海床细颗粒渗流测量方法研究

Measuring method on the seepage of fine particles on seabed based on chemical tracer

海床内部孔隙水及细颗粒的渗流和输运对于海底沉积动力过程、海床稳定性有重要影响。针对海床内部渗流发展过程难于描述、细颗粒渗流难于定量测定的问题,本文以在海床中物理化学性质稳定的白色氢氧化镁粉末作为示踪剂,通过分层取样加盐酸反应及离子色谱测试等手段,实现海床细颗粒渗流的指示及定量测量。试验及分析表明,本方法清晰显示了细颗粒在动荷载引起的粉土海床内部超孔隙水压力和向上的渗流压力梯度作用下向上运移,形成规模和形状各异的渗流通道,最终部分到达海床表面的渗流发展过程,实现了细颗粒从海床内部至床面逐层渗流量的定量表征,对于进一步理清波浪作用下粉土海床液化、渗流、再悬浮耦合机理及开发相应的定量评价方法具有重要意义。

The seepage and transport of pore water and fine particles on the seabed have an important impact on the dynamic process of seabed deposition and the stability of seabed. To solve the difficulty in describing the seepage development process and quantifying the seepage mass of fine particles on seabed, we used white magnesium hydroxide powder that has good physical and chemical stability at seabed to indicate and qualify the process of fine sediments seepage via stratified sampling, reacting with hydrochloric acid, and ion chromatography. Experiments and analysis indicate that the proposed method could clearly describe the whole seepage development process including the upward migration of fine particles, the formation of different-scaled seepage channels, and the reach of partial tracer to the seabed surface, from which the seabed silt movement under cyclic load-induced excess pore water pressure and upward seepage pressure gradient were clearly presented and thus quantitative characterization of the layer-by-layer seepage of fine particles from the interior of the seabed to the bed surface was realized. This study in silt seabed. Moreover, the proposed method achieves quantitative characterization of the seepage mass of fine particles from the interior to the surface of seabed, which provides a practical tool for further clarify the coupling mechanism and developing quantitative evaluation methods of wave-induced liquefaction, seepage, and re-suspension of silt seabed.