基于核磁共振技术的淤泥固化水分转化机制研究

Study of water transfer mechanism during sediment solidification process based on nuclear magnetic resonance technology

为了揭示淤泥固化体的微细观水分分布与工程特性的内在联系,针对水泥固化湖泊淤泥,基于柔性壁渗透、无侧限抗压及核磁共振(NMR)试验,探明淤泥固化过程中的水分转化和孔隙结构演化机制,并与固化体的渗透系数k、无侧限抗压强度q_u和变形模量E_(50)建立关联。试验结果表明:7d龄期内水化反应速率快,淤泥固化体内的大量孔隙水转化成水化物中的化合水,最可几孔径减小,形成孔隙结构骨架主体,导致k值降低、q_u和E_(50)增大;7d后,只有当孔隙水扩散穿透水化物膜层,水化反应才继续缓慢进行,但q_u和E_(50)仍大幅增长;化合水量M_(hw)与lgk存在线性关系,而M_(hw)-q_u和M_(hw)-E_(50)均呈指数关系。基于微观水分参数与工程特性的量化关系模型,可充分揭示水泥固化淤泥的宏微观演化机制。

To reveal the intrinsic correlation between the micro-meso moisture-distribution and the engineering properties of the solidified sediments, the lake sediments were solidified by cement. The mechanisms of water transfer and pore structure development in the process of sediment solidification were explored using the nuclear magnetic resonance test. The relationships of the moisture parameters with the permeability k, strength qu and deformation modulus E50 of solidified specimens were investigated. The experimental results showed that the hydration rate was fast within 7 days, and the pore water in the sediment solidification transferred into hydration water. Meanwhile, the most probable pore size decreased, which caused a decrease in k and increases in qu and E50, and hence inducing the formation of the pore structure. However, after 7 days, the hydration reaction continued slowly only if the water diffused and penetrated through hydrates membrane. Significant increases in qu and E50 were also observed for this case. The hydration water Mhwvaried as a linear function of lgk, however, exponential relations were existed between Mhw and qu,Mhw and E50. Based on the quantified relation model between the micro moisture parameters and the engineering properties, the macro and micro evolution mechanisms of the cement solidified sediment were revealed.