Abstract Rock salt is considered as a favorable host rock material for natural gas storage due to its low permeability, fast self-healing ability and unique creep behavior. Characterizing engineering properties of rock salt especially interbedded salt under complicated geological storage conditions associated with temperature variations remains challenging. This research integrates physical and numerical experiments to investigate the temperature effect on the engineering behavior of pure and interbedded salt. Thermo-mechanical coupled triaxial compression tests are carried out on both pure (Ash-grey Rock Salt and Charcoal-grey Rock Salt) and impure (Rock Salt with Mudstone interbedded) rock salt specimens. To reveal the underlying mechanism of thermal-induced deformation and cracking of salt at grain scale, we configure a discrete element model and incorporate smooth-joint contacts to capture the interfacial behavior in the bedded salt. Experimental results indicate that the compressive strength and failure mode of rock salt is highly susceptible to temperature. The increasing temperature enhances the ductility of salt whereas lowers its peak compressive strength. Numerical results provide a micromechanical explanation that the attenuated compressive strength of salt under high temperature is attributed to the evolution of micro-cracks. The presence of the mudstone layer increases the overall material strength, confines the crack propagation orientations, and therefore limits the transverse deformation of the bedded salt. This study is expected to bring new insights into the micro-mechanical study of bedded salt and improve the long-term assessment of geological storage facilities.

中文翻译：

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温度对纯岩盐和互层岩盐影响的实验和 DEM 研究

摘要 岩盐具有渗透率低、自愈能力强和独特的蠕变特性，被认为是一种良好的储气围岩材料。在与温度变化相关的复杂地质储存条件下，表征岩盐尤其是互层盐的工程特性仍然具有挑战性。本研究将物理和数值实验相结合，以研究温度对纯盐和互层盐的工程行为的影响。对纯（灰灰色岩盐和炭灰色岩盐）和不纯（岩盐与泥岩互层）岩盐试样进行了热机械耦合三轴压缩试验。为了揭示晶粒尺度上盐的热致变形和开裂的潜在机制，我们配置了一个离散单元模型，并结合了平滑接头接触来捕捉层状盐中的界面行为。实验结果表明，岩盐的抗压强度和破坏模式对温度非常敏感。升高的温度提高了盐的延展性，而降低了其峰值抗压强度。数值结果提供了一种微观力学解释，即高温下盐的抗压强度衰减归因于微裂纹的演变。泥岩层的存在增加了整体材料强度，限制了裂纹扩展方向，因此限制了层状盐的横向变形。