水化学环境对湛江组黏土结构强度的影响研究

为研究水化学环境对湛江组黏土结构强度的影响,收集湛江地区地下水水文地质资料,并通过钻孔取水进行化学分析,分析该区地下水的化学环境与影响因素;利用离心过滤法提取土中水溶液,调查土中溶液的化学成分与特性;在此基础上,采用选择溶解法去除土中胶结物质,利用扫描电子显微镜与能谱分析,对比分析去除胶结物质前后的微观结构变化。研究表明:湛江地区的地下水与湛江组黏土中水溶液的化学构成与比例含量基本一致,水化学类型为Cl-Na型,表现出偏酸性与富含铁离子的特征,水中大量的铁为土颗粒的联结提供了胶结物质,酸性环境促使游离氧化铁产生胶结效果进而提高土的结构强度。最后,提出了考虑地下水环境影响的湛江组黏土结构强度的形成机理,研究表明湛江组黏土较强的结构性源于开放式的絮凝结构加上颗粒间的强胶结作用。

Effects of hydrochemistry on structural strength of Zhanjiang formation clay

The principal purpose of the present work is to investigate the effects of hydrochemistry on the structural strength of Zhanjiang formation clay. Several hydrogeological data and chemical composition of groundwater by drilling are collected and analyzed to evaluate the chemical environment of groundwater in Zhanjiang area. The water solution in soils is extracted by using the centrifugal filter method to measure its chemical composition. Furthermore, changes of microstructure before and after removing the cementing material are studied using the scanning electron microscopy and energy spectrum analysis. The results show that the water solution in Zhanjiang formation clay has chemical compositions and relative content similar to the groundwater with the chemical types of Cl-Na, showing acidic and iron-rich characteristics. The high content of iron can provide cementing materials, and free iron oxides further produce a strong bond between soil particles in the acidic environment. According to the results, an effect mechanism of hydrochemistry on the structural strength of Zhanjiang formation clay is proposed. The strong structural characteristic is caused by an open flocculation structure and the bond between the particles.