苗胜军, 杨鹏锦, 王辉, 梁明纯, 王亚欣. 循环荷载作用下粉砂岩疲劳流变损伤模型研究[J]. 工程力学, 2022, 39(7): 70-80. DOI: 10.6052/j.issn.1000-4750.2021.03.0235
引用本文: 苗胜军, 杨鹏锦, 王辉, 梁明纯, 王亚欣. 循环荷载作用下粉砂岩疲劳流变损伤模型研究[J]. 工程力学, 2022, 39(7): 70-80. DOI: 10.6052/j.issn.1000-4750.2021.03.0235
MIAO Sheng-jun, YANG Peng-jin, WANG Hui, LIANG Ming-chun, WANG Ya-xin. STUDY ON FATIGUE RHEOLOGICAL DAMAGE MODEL OF SILTSTONE UNDER CYCLIC LOADING[J]. Engineering Mechanics, 2022, 39(7): 70-80. DOI: 10.6052/j.issn.1000-4750.2021.03.0235
Citation: MIAO Sheng-jun, YANG Peng-jin, WANG Hui, LIANG Ming-chun, WANG Ya-xin. STUDY ON FATIGUE RHEOLOGICAL DAMAGE MODEL OF SILTSTONE UNDER CYCLIC LOADING[J]. Engineering Mechanics, 2022, 39(7): 70-80. DOI: 10.6052/j.issn.1000-4750.2021.03.0235

循环荷载作用下粉砂岩疲劳流变损伤模型研究

STUDY ON FATIGUE RHEOLOGICAL DAMAGE MODEL OF SILTSTONE UNDER CYCLIC LOADING

  • 摘要: 针对现有流变模型难以有效描述循环荷载作用下岩石变形及疲劳损伤演化特征等问题,开展了粉砂岩循环加卸载试验,分析了不同上限荷载下岩石的流变规律与疲劳特性。基于Kachanov蠕变损伤理论建立损伤变量,引入一个带应变触发和应力阈值的黏塑性元件,与Burgers模型串联构建循环荷载作用下岩石疲劳流变损伤模型;将正弦波应力函数替换流变微分本构方程中的恒定应力,推导岩石在循环荷载下的一维、三维微分型损伤本构方程,再根据叠加原理得到模型的黏弹塑性流变损伤方程。适用性验证表明,新建模型不仅可以精确地反映循环加卸载过程中粉砂岩的衰减、稳态流变阶段,还可以有效地描述上限荷载高于疲劳强度时的加速流变阶段。通过粉砂岩疲劳损伤流变全过程定量化分析,提出加速流变阶段的临界损伤阈值和破坏失稳判据,并给出加速流变阶段的启始时间、持续时间及疲劳寿命预测方法,模型对岩体工程长期稳定性评价具有一定的理论指导意义。

     

    Abstract: The fatigue test of siltstone under cyclic loading is carried out, aiming at the problem that the deformation law and the damage evolution characteristics of rock under cyclic loading cannot be described rigorously by the existing rheological models. According to the analysis of the test results, a damage variable established by Kachanov's creep damage theory is introduced into a viscoplastic element with strain trigger and stress threshold, then a new rheological constitutive model under cyclic loading is constructed through series with Burgers model and the viscoplastic element. In the meanwhile, the sine wave cyclic load stress function is used to replace the constant stress in the rheological differential constitutive equation. The one-dimensional and three-dimensional differential damage constitutive equation of rock is inferred by the integral method, and then the viscoelastic plastic rheological damage equation is inferred by a superposition principle. The parameters of the new rheological model are derived by fitted fatigue deformation curves of siltstone. The applicability verification shows that: the new rheological model can not only accurately reflect the attenuation and steady-state rheological deformation stage of siltstone, but also effectively describe the accelerated rheological stage when the upper limit of cyclic load is higher than the fatigue strength. Finally, the critical damage threshold and instability criterion of accelerated rheology are proposed, and the prediction methods of the start time, duration and fatigue life of accelerated rheology are developed. The model has certain theoretical significance for the long-term stability prediction of rock engineering.

     

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