Salt cavern energy storage technology contributes to energy reserves and renewable energy scale-up. This study focuses on salt cavern gas storage in Jintan to assess the long-term stability of its surrounding rock under frequent operation. The fatigue test results indicate that stress holding significantly reduces fatigue life, with the magnitude of stress level outweighing the duration of holding time in determining peak strain. Employing a machine learning approach, the impact of various factors on fatigue life and peak strain was quantified, revealing that higher stress limits and stress holding adversely impact the fatigue index, whereas lower stress limits and rate exhibit a positive effect. A novel fatigue-creep composite damage constitutive model is constructed, which is able to consider stress magnitude, rate, and stress holding. The model, validated through multi-path tests, accurately captures the elasto-viscous behavior of salt rock during loading, unloading, and stress holding. Sensitivity analysis further reveals the time- and stress-dependent behavior of model parameters, clarifying that strain changes stem not only from stress variations but are also influenced by alterations in elasto-viscous parameters. This study provides a new method for the mechanical assessment of salt cavern gas storage surrounding rocks.

中文翻译：

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复杂循环载荷作用下金坛盐岩疲劳特性及本构模型


盐穴储能技术有助于能源储备和可再生能源的扩大。本研究以金坛盐穴储气库为研究对象，评估其围岩在频繁作业下的长期稳定性。疲劳测试结果表明，应力保持会显著缩短疲劳寿命，在确定峰值应变时，应力水平的大小超过了保持时间的持续时间。采用机器学习方法，量化了各种因素对疲劳寿命和峰值应变的影响，揭示了较高的应力极限和应力保持对疲劳指数有不利影响，而较低的应力极限和刚度则表现出积极影响。构建了一种新的疲劳-蠕变复合损伤本构模型，该模型能够考虑应力大小、速率和应力保持。该模型通过多路径测试验证，可准确捕捉盐岩在加载、卸载和应力保持过程中的弹性粘性行为。敏感性分析进一步揭示了模型参数的时间和应力依赖性行为，阐明了应变变化不仅源于应力变化，还受到弹性粘性参数变化的影响。本研究为盐穴储气库围岩力学评价提供了一种新方法。