温度和盐/碱作用下膨润土-砂-石墨缓冲材料膨胀力性能演化

刘晓燕; 刘路路; 蔡国军; 刘松玉

doi:10.11779/CJGE20220821

温度和盐/碱作用下膨润土-砂-石墨缓冲材料膨胀力性能演化 English Version

刘晓燕^{1, 3, 4,},
刘路路^{2, 3, 4},
蔡国军^{3, 4, ,},
刘松玉⁴

1.
中国矿业大学力学与土木工程学院, 江苏徐州 221116
2.
中国矿业大学深部岩土力学与地下工程国家重点试验, 江苏徐州 221116
3.
安徽建筑大学土木工程学院, 安徽合肥 230601
4.
东南大学岩土工程研究所, 江苏南京 211189

基金项目:

国家杰出青年基金项目 42225206

国家自然科学基金项目 42207180

国家自然科学基金项目 42302320

江苏省卓越博士后计划 2022ZB526

中国博士后科学基金面上项目 2022M723383

中国博士后科学基金面上项目 2023M733746

江苏省自然科学基金青年项目 BK20221136

详细信息

作者简介:
刘晓燕(1990—)，女，山东潍坊人，讲师，博士后，主要从事非饱和土工程性质与能源岩土工程等方面的研究工作。E-mail: happyliuxiaoyan@163.com

通讯作者:
蔡国军, E-mail: focuscai@163.com

中图分类号: TU43
计量
- 文章访问数: 315
- HTML全文浏览量: 34
- PDF下载量: 109
出版历程
- 收稿日期: 2022-06-29
- 网络出版日期: 2023-12-11
- 刊出日期: 2023-11-30

Evolution of swelling pressure properties of bentonite-sand-graphite buffer materials under action of temperature and salt/alkali

LIU Xiaoyan^{1, 3, 4,},
LIU Lulu^{2, 3, 4},
CAI Guojun^{3, 4, ,},
LIU Songyu⁴

1.
School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China
2.
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China
3.
School of Civil Engineering, Anhui Jianzhu University, Hefei 230601, China
4.
Institute of Geotechnical Engineering, Southeast University, Nanjing 211189, China

摘要

摘要: 缓冲材料是核废料等高放废物地质处置库的最后一道工程屏障，要想科学合理地评估缓冲材料的实际工作性能，需对温度场和化学场作用下非饱和缓冲材料的膨胀特性有清晰的认识。以膨润土-砂-石墨缓冲材料（BSG）为硏究对象，基于自主研发的膨胀力试验装置，系统研究了温度、化学溶液对BSG混合物的膨胀力的影响。结果表明：高温和化学溶液降低膨胀力。阳离子类型的影响通过其化学活性的差异来解释。Ca²⁺离子具有比Na⁺离子更高的交换容量。温度对膨胀力的影响超过了阳离子类型，在室温条件下，加入CaCl₂溶液的BSG混合物的膨胀力高于加入NaCl溶液的，而高温下规律则相反。随着NaOH溶液pH值的增加，膨胀力减小。在较高的温度下，下降速率取决于NaOH溶液pH值。高浓度的OH^-有利于双层膨胀和土体结构重排，不同浓度的NaOH溶液对膨胀力的影响表现为Na⁺和OH^-的相互作用。土体结构重新排列引起的双层膨胀力的增加和膨胀力的降低分别由双层厚度的减小和蒙脱石和硅酸盐矿物的溶解控制。
- 膨胀土-砂-石墨混合物 /
- 膨胀力 /
- 温度 /
- 盐溶液 /
- 碱溶液
Abstract: The buffer materials are the last engineering barrier for the repository of high-level radioactive wastes. It is necessary to have a deep understanding of the swelling characteristics of unsaturated buffer materials under the action of temperature and chemical fields. The bentonite-sand-graphite (BSG) buffer materials are taken as the research object. Based on the self-developed swelling pressure test devices, the influences of temperature and chemical solution on the swelling pressure of the BSG mixture are systematically studied. The results show that the high temperature and chemical solution reduce the swelling pressure. The influences of cation type are explained by the difference of its chemical activity. Ca²⁺ has higher exchange capacity than Na⁺. The influences of temperature on the swelling pressure are more than those of cation type. At room temperature, the swelling pressure of the BSG mixture with CaCl₂ solution is higher than that with NaCl solution, while the rule is opposite at high temperature. The swelling pressure decreases with the increase of pH value of NaOH solution. At higher temperatures, the rate of decline depends on the pH of the NaOH solution. High OH^- concentration is conducive to double-layer swelling and rearrangement of soil structure. The influences of NaOH solution with different concentrations on the swelling pressure are shown by the interaction of Na⁺and OH^-. The increase and decrease of the double-layer swelling pressure caused by the rearrangement of soil structure are controlled by the decrease of the double-layer thickness and the dissolution of montmorillonite and silicate minerals, respectively.
- bentonite-sand-graphite mixture /
- swelling pressure /
- temperature /
- salt solution /
- alkali solution

HTML全文

图 1 膨润土、石英砂和石墨的粒度分布

Figure 1. Grain-size distribution curves of bentonite, quartz sand and graphite

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图 2 膨胀力实验装置

Figure 2. Test devices for swelling pressure

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图 3 不同盐溶液浓度条件下BSG混合物膨胀力变化

Figure 3. Variation of swelling pressure of BSG mixture under different salt solution concentrations

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图 4 不同pH值NaOH溶液下BSG混合物膨胀力的变化

Figure 4. Variation of swelling pressure of BSG mixture under NaOH solution with different pH

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图 5 NaOH溶液pH值对BSG混合物最大膨胀力的影响

Figure 5. Influences of pH value of NaOH solution on maximum swelling pressure of BSG mixture

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图 6 BSG混合物膨胀力-温度演化曲线

Figure 6. Evolution curves of swelling pressure-temperature of BSG mixture

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图 7 BSG混合物最大膨胀力-温度变化规律

Figure 7. Variation of maximum swelling pressure of BSG mixture under temperature

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图 8 温度-盐溶液共同作用下BSG混合物膨胀力变化

Figure 8. Variation of swelling pressure of BSG mixture under combined action of temperature and salt solution

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图 9 温度与盐溶液共同作用下BSG试样最大膨胀力变化

Figure 9. Variation of maximum swelling pressure of BSG mixture under combined action of temperature and salt solution

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图 10 温度与碱溶液共同作用下BSG混合物膨胀力变化

Figure 10. Variation of swelling pressure of BSG mixture under combined action of temperature and alkali solution

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图 11 恒定体积下膨润土膨胀过程及微观结构概念图^[22]

Figure 11. Conceptual diagram of swelling process of bentonite and microstructure at constant volume^[22]

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图 12 扩散双层收缩示意图^[23]

Figure 12. Schematic diagram of diffusion double-layer shrinkage^[23]

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图 13 NaOH溶液渗透BSG混合物的微观结构（pH=14）

Figure 13. Microstructure of BSG mixture permeated by NaOH solution (pH=14)

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表 1 石英砂的物理特性

Table 1 Physical parameters of sand

土体基本性质	数值
限制粒径D₆₀/mm	0.37
中值粒径D₅₀/mm	0.35
有效粒径D₁₀/mm	0.31
不均匀系数 C_u	1.12
曲率系数C_c	0.95
密度 $\rho$ /(g·cm^-3)	1.40
${\rho _{{\text{dmax}}}}$ /(g·cm^-3)	1.69
${\rho _{{\text{dmin}}}}$ /(g·cm^-3)	1.35

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