摘要
Rocks will suffer different degree of damage under freeze-thaw(FT)cycles,which seriously threatens the long-term stability of rock engineering in cold regions.In order to study the mechanism of rock FT damage,energy calculation method and energy self-inhibition model are introduced to explore their energy characteristics in this paper.The applicability of the energy self-inhibition model was verified by combining the data of FT cycles and uniaxial compression tests of intact and pre-cracked sandstone samples,as well as published reference data.In addition,the energy evolution characteristics of FT damaged rocks were discussed accordingly.The results indicate that the energy self-inhibition model perfectly characterizes the energy accumulation characteristics of FT damaged rocks under uniaxial compression before the peak strength and the energy dissipation characteristics before microcrack unstable growth stage.Taking the FT damaged cyan sandstone sample as an example,it has gone through two stages dominated by energy dissipation mechanism and energy accumulation mechanism,and the energy rate curve of the pre-cracked sample shows a fall-rise phenomenon when approaching failure.Based on the published reference data,it was found that the peak total input energy and energy storage limit conform to an exponential FT decay model,with corresponding decay constants ranging from 0.0021 to 0.1370 and 0.0018 to 0.1945,respectively.Finally,a linear energy storage equation for FT damaged rocks was proposed,and its high reliability and applicability were verified by combining published reference data,the energy storage coefficient of different types of rocks ranged from 0.823 to 0.992,showing a negative exponential relationship with the initial UCS(uniaxial compressive strength).In summary,the mechanism by which FT weakens the mechanical properties of rocks has been revealed from an energy perspective in this paper,which can provide reference for related issues in cold regions.
在冻融循环下岩石会遭受不同程度的损伤,严重威胁着寒区岩体工程的长期稳定性。为了研究岩石冻融损伤机理,本文引入能量计算方法和能量自抑制模型,探讨寒区岩石的能量特性。结合完整砂岩和预制裂隙砂岩的冻融循环和单轴压缩试验,以及已发表文献的数据,验证了能量自抑制模型的适用性,并讨论了冻融损伤岩石的能量演化特征。结果表明:能量自抑制模型较好地描述了单轴压缩下冻融损伤岩石峰值强度前的能量积累特征和微裂纹不稳定扩展阶段前的能量耗散特征。以冻融损伤青砂岩试件为例,其经历了以能量耗散机制和能量积累机制为主的两个阶段,预制裂隙试件的能量率曲线在接近破坏时呈现跌落-回升现象。根据已发表的文献数据,发现峰值总输入能和储能极限符合指数式的冻融衰减模型,相应的衰减常数分别位于0.0021~0.1370以及0.0018~0.1945之间。最后,提出了冻融损伤岩石的线性能量存储方程,并结合已发表文献数据验证了其高可靠性和适用性,不同类型岩石的储能系数位于0.823~0.992之间,与初始单轴抗压强度UCS呈负指数函数关系。总之,本文从能量角度揭示了冻融弱化岩石力学性能的机理,可为寒区相关问题提供参考。
基金
Project(52174088)supported by the National Natural Science Foundation of China
Project(104972024JYS0007)supported by the Independent Innovation Research Fund Graduate Free Exploration,Wuhan University of Technology,China。
