高碱溶液对高庙子膨润土侵蚀作用的研究

陈宝; 张会新; 陈萍

高碱溶液对高庙子膨润土侵蚀作用的研究 English Version

同济大学岩土及地下工程教育部重点实验室，上海 200092

基金项目: 国家自然科学基金项目（40802069）

详细信息

作者简介:
陈宝(1973- )，男，江苏睢宁人，博士，副教授，博士生导师，主要从事地下工程及岩土力学的研究与教学工作。E-mail: chenbao@tongji.edu.cn。

中图分类号: TU411
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出版历程
- 收稿日期: 2012-04-25
- 发布日期: 2013-01-31

Erosion effect of hyper-alkaline solution on Gaomiaozi bentonite

Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China

摘要

摘要: 采用NaOH溶液模拟高放射性核废物处置库中可能产生的高碱性孔隙水，对初始干密度为1.70 g/cm³的高庙子（GMZ）膨润土试样进行渗透侵蚀试验，借助扫描电镜（SEM）和透射电镜（TEM）对侵蚀后试样的表观特性进行观察分析，对碱溶液侵蚀对膨润土试样膨胀性、渗透性、孔隙比和化学成分的影响规律进行解释，以研究碱性孔隙水侵蚀对膨润土性能影响的微观机理。结果表明，GMZ膨润土主要成分蒙脱石呈层片状结构，蒙脱石水化会在其表面形成羽翼状的胶体，会堵塞试样的孔隙；高碱性溶液的侵蚀会造成膨润土水化产生的羽翼状胶体溶解和膨润土结构的不可逆性破坏，并且破坏程度与碱溶液的浓度成正相关关系；经高碱性溶液侵蚀的膨润土试样，其表面有明显的溶蚀痕迹，说明碱溶液的入渗侵蚀会造成膨润土有效成分蒙脱石的溶解，试验结果与X射线衍射（XRD）测试结果吻合。因此，碱性孔隙水的入渗侵蚀会逐渐溶解膨润土中的蒙脱石，破坏了膨润土的结构，增大了膨润土的孔隙率，进而降低了膨润土的膨胀性，提高了膨润土的长期渗透性，最终造成膨润土的封闭和缓冲性能降低。
- 膨润土 /
- 高碱性孔隙水 /
- 扫描电镜 /
- 透射电镜
Abstract: Permeability and erosion experiments are carried out on Gaomiaozi (GMZ) bentonite specimens with the dry density of 1.70 g/cm³, where NaOH solution is employed to simulate hyper-alkaline pore water, which is likely be produced in highly active nuclear waste repositories. Surface properties alterations of the specimens observed with the scanning electron microscope (SEM) and the transmission electron microscope (TEM) are used to interpret the influence of hyper-alkaline solution on the swelling potential, permeability, porosity and composition of bentonite, and to assess the micro-mechanism of hyper-alkaline pore-water effect on the properties of bentonite. The results show that GMZ bentonite presents a flake layer structure, and that gels with the shape of wings are formed on the surface of montmorillonite during hydration. The dissolution of gels produced by hydration and the destruction of bentonite structure by erosion due to hyper-alkaline water are observed too. A positive relation between alterative degree and solution concentration is also observed. The surface erosion of bentonite specimens eroded by hyper-alkaline solutions is shown as the dissolution of montmorillonite, which is identical to the results obtained using X-ray diffraction (XRD) tests. Therefore, submitting the bentonite to long-term infiltration of hyper-alkaline pore-water may lead to dissolution of montmorillonite, destruction of bentonite structure, increase of porosity, decrease of swelling potential, and amplification of permeability as well, which generally weakens its sealing and buffering properties.
- bentonite /
- hyper-alkaline pore water /
- SEM /
- TEM

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参考文献(20)

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