张彤炜, 邓永锋, 张帆宇, 张虎元, 兰恒星. 2018: 黏性土次固结行为的盐分和矿物效应研究. 工程地质学报, 26(5): 1318-1325. DOI: 10.13544/j.cnki.jeg.2018181
    引用本文: 张彤炜, 邓永锋, 张帆宇, 张虎元, 兰恒星. 2018: 黏性土次固结行为的盐分和矿物效应研究. 工程地质学报, 26(5): 1318-1325. DOI: 10.13544/j.cnki.jeg.2018181
    ZHANG Tongwei, DENG Yongfeng, ZHANG Fanyu, ZHANG Huyuan, LAN Hengxing. 2018: SALINITY AND MINERALOGY EFFECTS ON SECONDARY CONSOLIDATION BEHAVIOR OF CLAYS. JOURNAL OF ENGINEERING GEOLOGY, 26(5): 1318-1325. DOI: 10.13544/j.cnki.jeg.2018181
    Citation: ZHANG Tongwei, DENG Yongfeng, ZHANG Fanyu, ZHANG Huyuan, LAN Hengxing. 2018: SALINITY AND MINERALOGY EFFECTS ON SECONDARY CONSOLIDATION BEHAVIOR OF CLAYS. JOURNAL OF ENGINEERING GEOLOGY, 26(5): 1318-1325. DOI: 10.13544/j.cnki.jeg.2018181

    黏性土次固结行为的盐分和矿物效应研究

    SALINITY AND MINERALOGY EFFECTS ON SECONDARY CONSOLIDATION BEHAVIOR OF CLAYS

    • 摘要: 我国江苏北部连云港地区海相软土蒙脱石族矿物含量相对较高,且在海陆交互环境中沉积形成,沉积过程中具有孔隙水盐分较高的特点,但在后沉积过程中由于地表和地下淡水入侵,会使孔隙水盐分发生变化,而相应的次固结行为的变化规律尚不明晰,因此需要深入了解矿物成分、孔隙水盐分在软黏土次固结行为中的作用机制。由于天然软黏土的矿物成分、孔隙水成分差异较大,试验材料采用矿物成分均一的商用高岭土与膨润土组成的人工黏土作为研究对象,配制不同浓度的NaCl溶液作为孔隙水,模拟孔隙水盐分变化。通过常规固结试验,发现对于含蒙脱石矿物的人工黏土,压缩指数Cc随着盐分浓度的增加而减小,主固结完成时间随盐分的增加而提前,且同一应力水平下和孔隙比下,次固结系数随着盐分的增加而减小。在同样的上部荷载下,次固结系数与压缩指数的比值Cα/Cc不再保持为经验常数,而是随着孔隙水盐分的增加而偏离经验值,主要原因为盐分对水膜蠕变的影响。但是,对于主要由高岭石矿物构成的人工黏土,孔隙水盐分浓度则未对其次固结参数产生明显的影响。因此,如果场地的黏性土蒙脱石含量较高且孔隙水含盐量较高,则需要考虑孔隙水盐分的变迁对地基长期变形的影响。

       

      Abstract: The soft marine clay, deposited under the marine environment in North of Jiangsu plain, is rich of the montmorillonite and saline water. During the post-sedimentary period, the soil suffers the invasion of the surface and underground freshwater, leading to the alteration and reduction of pore water salinity. Presently, the secondary consolidation behavior is generally based on the in-situ soil behavior in a current environment. Hence, this non-consideration on the pore water salinity alteration may result in the insufficient redundancy and potential risk. To clarify the evolution of the soils' secondary consolidation behavior due to the alteration of pore water salinity, the impact of pore water salinity and clay mineral on the soil behavior is necessary to be investigated. To simplify the mineralogy influence, the commercial kaolin and bentonite are selected. The consolidation behavior of artificial clays changing with pore water salinities(NaCl solution) are investigated using oedometer tests. The results showed that the compression index Cc and the primary consolidation process of bentonite-kaolinite mixture decrease with water salinity increasing. At a certain applied stress and void ratio, the secondary consolidation coefficient Cα of montmorillonitic clay also decreases with water salinity increasing. Meanwhile, the ratio of Cα to Cc is not a constant and deviated from empirical data. The main mechanism is that the compression of diffused double layer. However, the water salinity does not significantly influence secondary consolidation behavior of kaolin. Therefore, it is important to take pore water salinity into consideration for secondary consolidation prediction of montmorillonite-rich clays.

       

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