Abstract Artificial ground freezing has been used in the mine of Cigar Lake to mitigate groundwater infiltration to underground mining operations and stabilize the heterogeneous and poor ground. In addition to the control of the freezing process, the ability to predict accurately the ground movements and the site stability is crucial to a successful use of this technique. This requires developing adequate constitutive models able to correctly reproduce the mechanical behavior of water-saturated soils at low temperatures. To achieve this goal, a digital control servo-hydraulic triaxial test facility with full data acquisition has been developed, and an experimental program was carried out to investigate the mechanical behavior of metapelite samples collected from the mine of Cigar Lake. A series of triaxial compression tests were conducted on reconstituted and natural frozen metapelite specimens under different strain rates (2.5, 4.5 and 8 × 10−6 s−1) and at different temperatures (−10, −20 and −30 °C) and confining pressures (1, 5 and 9 MPa). The experimental results showed that the stress-strain behavior of frozen metapelite, in the studied range of temperature and confining pressure, is elasto-viscoplastic, strain hardening, highly sensitive to temperature and moderately sensitive to the confinement level. They also proved that the transition contractancy-dilatancy is significantly dependent on temperature and suggested the existence of a critical temperature between −20 and −10 °C that represents a dilatancy threshold. To capture these observations, a recent phenomenological model developed for crystalline rocks was used. The model accounts for the phenomena of hardening, dilatancy/contractancy and time dependency and was extended to include the effect of temperature on the frozen material's distorsion and on the dilatancy onset. The proposed model was validated using the triaxial compression tests on metapelite and experimental results from literature on frozen sand.

中文翻译：

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冷冻变泥质岩的力学行为：实验室研究和本构建模

摘要 雪茄湖矿山采用人工地层冻结技术，缓解地下水渗入地下采矿作业，稳定非均质、贫瘠的地层。除了冻结过程的控制之外，准确预测地面运动和场地稳定性的能力对于成功使用该技术至关重要。这需要开发足够的本构模型，能够正确再现低温下水饱和土壤的力学行为。为了实现这一目标，开发了一种具有全数据采集功能的数控伺服液压三轴试验设备，并开展了一项实验程序，以研究从雪茄湖矿山采集的变泥岩样品的力学行为。在不同应变率（2.5、4.5 和 8 × 10-6 s-1）和不同温度（-10、-20 和 -30 °C）下对重组和天然冷冻变泥质岩样品进行了一系列三轴压缩试验，并且围压（1、5 和 9 兆帕）。实验结果表明，在所研究的温度和围压范围内，冻结变泥岩的应力-应变行为为弹粘塑性、应变硬化、对温度高度敏感、对约束水平中等敏感。他们还证明了转变收缩-膨胀显着依赖于温度，并表明存在一个介于 -20 到 -10 °C 之间的临界温度，这代表了一个膨胀阈值。为了捕捉这些观察结果，使用了最近为结晶岩开发的现象学模型。该模型考虑了硬化、剪胀/收缩和时间依赖性现象，并扩展到包括温度对冷冻材料变形和剪胀开始的影响。所提出的模型通过对 metapelite 的三轴压缩试验和关于冻沙文献的实验结果进行了验证。