Rock engineering in the Tibetan Plateau is usually suffered severe freeze-thaw (F-T) deterioration, triggering numerous geotechnical engineering disasters. As the essential triggering factor of F-T damage, the frost heave pressure (FHP) in rocks should be quantitatively described and predicted. In this study, a novel theoretical model is established and validated to estimate the critical entire evolution process of FHP in fractured rocks subjected to repeated F-T deterioration, in which the influence of fracture geometric configuration, rock mechanical properties and F-T conditions are comprehensively considered. Besides, given the obvious five-stage manner of FHP evolution, the combination effect of different dominant mechanisms in different stages is theoretically addressed. During freezing, after a silence stage induced by temperature above freezing point of water, volumetric expansion and frost-heave cracking separately controls the generation and reduction stages of FHP, and the solutions are obtained based on elastic mechanics and Griffith energy balance theory, respectively. During thawing, ice segregation dominates the second-arising stage of FHP that is quantitatively described via segregation potential and water migration velocity, and then the FHP enters the dissipation stage owing to complete melting of fracture ice. In addition, a decay coefficient is introduced to estimate the influence of F-T cycle number on FHP, and a piecewise FHP model is finally constructed for fractured rocks subjected to repeated F-T deterioration. To validate our new model, a total of 12 F-T cycle tests with real-time FHP monitoring are conducted on granite and sandstone specimens considering three typical influencing factors, i.e., fracture width, rock types and freezing temperatures. A rational consistency is identified between the theoretical and testing results in terms of the FHP evolution curves and the peak FHPs in rock fracture, demonstrating the generalizability and robustness of our proposed model.

中文翻译：

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反复冻融劣化裂隙岩体冻胀压力模型


青藏高原岩石工程经常遭受严重的冻融破坏，引发众多岩土工程灾害。作为F-T损伤的重要触发因素，岩石中的冻胀压力（FHP）应该被定量描述和预测。在这项研究中，建立并验证了一种新颖的理论模型来估计反复F-T劣化的裂隙岩石中FHP的关键整个演化过程，其中综合考虑了裂缝几何构型、岩石力学性质和F-T条件的影响。此外，考虑到FHP演化明显的五阶段方式，从理论上解决了不同阶段不同主导机制的组合效应。结冰过程中，经过水冰点以上温度引起的静默阶段后，体积膨胀和冻胀破裂分别控制FHP的产生和减少阶段，分别基于弹性力学和格里菲斯能量平衡理论得到了解。融化过程中，冰的分离主导了FHP的第二次出现阶段，通过分离势和水迁移速度定量描述了FHP，然后由于裂隙冰的完全融化，FHP进入消散阶段。此外，引入衰减系数来估计F-T循环数对FHP的影响，最终针对反复F-T劣化的裂隙岩石构建分段FHP模型。为了验证我们的新模型，考虑到三个典型的影响因素，对花岗岩和砂岩样本进行了总共 12 次具有实时 FHP 监测的 F-T 循环测试，即、裂缝宽度、岩石类型和冻结温度。在岩石破裂的 FHP 演化曲线和峰值 FHP 方面，理论结果和测试结果之间存在合理的一致性，证明了我们提出的模型的普遍性和鲁棒性。