球状石墨–膨润土压实后的导热与防渗性能

doi:10.3724/1000-6915.jrme.2024.0763

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摘要片状石墨掺入到膨润土中能提高膨润土的导热性能但弱化其防渗能力，选择用球状石墨取代片状石墨的方法调节该矛盾，通过开展2种形态石墨掺入下石墨–膨润土混合物的热传导试验和饱和渗透试验，研究石墨几何形状与质量掺入率对石墨–膨润土混合物导热和防渗性能的影响规律。结果表明，球状石墨掺入率约为20%时，既能显著提高膨润土的导热性能(1.7 W/(m•K))，又能保证渗透系数(9.44×10－13 m/s)，满足缓冲层的最低要求 (≤1×10－12 m/s)；同时，最大膨胀力达到5.76 MPa，处于缓冲层的建议值范围(1～10 MPa)。引入临界石墨掺入率概念，确定球状石墨、片状石墨的临界掺入率分别为27.3%和16.4%。可以发现，球状石墨掺入率为20%时，石墨尚未在混合物中形成骨架，即石墨悬浮于膨润土中；而片状石墨掺入率为20%时，却已形成骨架，膨润土充填于石墨骨架中。据此，结合石墨–膨润土的孔隙分布特征和微观形貌，解释片状石墨提升膨润土导热、弱化防渗的原因，以及球状石墨优于片状石墨的物理机制，为提高处置库的运行安全提供科学指导。

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	谈云志1
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	魏康旭1
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	祝雨1
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	张金生1
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	明华军1
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关键词 ：土力学, 球状石墨, 膨润土, 导热系数, 渗透系数, 压实

Abstract：Incorporating flake graphite into bentoni te enhances its thermal conductivity but compromises its impermeability. To address this trade-off，spheroidal graphite was selected as a substitute for flake graphite. Thermal conductivity and saturated permeability tests were conducted on spheroidal graphite-bentonite mixtures to investigate the effects of graphite content and shape on both thermal conductivity and permeability properties of bentonite. The results show that a spheroidal graphite content of approximately 20% significantly enhances the thermal conductivity of bentonite(1.7 W/(m•K))，while ensuring the permeability coefficient(9.44×10－13 m/s) remains below the buffer layer?s threshold of ≤1×10－12 m/s. Concurrently，the maximum swelling pressure attained is 5.76 MPa，which falls within the recommended range of the buffer layer(1–10 MPa). Furthermore，the concept of critical graphite content is introduced，with the critical contents for spheroidal and flake graphite determined to be 27.3% and 16.4%，respectively. At a spheroidal graphite content of 20%，the graphite has not yet formed a skeleton within the mixture，indicating that it remains suspended in the bentonite. Conversely，at a flake graphite content of 20%，a skeleton forms with bentonite filling the spaces within the graphite structure. By analyzing the microscopic morphology and pore distribution characteristics of graphite-bentonite，this study elucidates why flake graphite enhances thermal conductivity while reducing impermeability. Additionally，it explains the physical mechanism by which spheroidal graphite outperforms flake graphite，providing scientific guidance for improving the operational safety of the repository.

Key words： soil mechanics spheroidal graphite bentonite thermal conductivity permeability coefficient compaction

引用本文:

谈云志1，2，魏康旭1，2，祝雨1，2，张金生1，2，明华军1，2. 球状石墨–膨润土压实后的导热与防渗性能[J]. 岩石力学与工程学报, 2025, 44(5): 1340-1348.
TAN Yunzhi1，2，WEI Kangxu1，2，ZHU Yu1，2，ZHANG Jinsheng1，2，MING Huajun1，2. Thermal conductivity and impermeability of spheroidal graphite-bentonite mixture after compaction. , 2025, 44(5): 1340-1348.

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https://rockmech.whrsm.ac.cn/CN/10.3724/1000-6915.jrme.2024.0763 或 https://rockmech.whrsm.ac.cn/CN/Y2025/V44/I5/1340

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