任建喜, 杨淏冰, 谢易, 等. 2024. 冻融雁行裂隙花岗岩单轴压缩宏细观疲劳特性试验研究[J]. 工程地质学报, 32(3): 840-850. doi: 10.13544/j.cnki.jeg.2023-0263.
    引用本文: 任建喜, 杨淏冰, 谢易, 等. 2024. 冻融雁行裂隙花岗岩单轴压缩宏细观疲劳特性试验研究[J]. 工程地质学报, 32(3): 840-850. doi: 10.13544/j.cnki.jeg.2023-0263.
    Ren Jianxi, Yang Haobing, Xie Yi, et al. 2024. Experimental study on macro-micro fatigue characteristics of freeze-thaw double-fissured granite under uniaxial compression[J]. Journal of Engineering Geology, 32(3): 840-850. doi: 10.13544/j.cnki.jeg.2023-0263.
    Citation: Ren Jianxi, Yang Haobing, Xie Yi, et al. 2024. Experimental study on macro-micro fatigue characteristics of freeze-thaw double-fissured granite under uniaxial compression[J]. Journal of Engineering Geology, 32(3): 840-850. doi: 10.13544/j.cnki.jeg.2023-0263.

    冻融雁行裂隙花岗岩单轴压缩宏细观疲劳特性试验研究

    EXPERIMENTAL STUDY ON MACRO-MICRO FATIGUE CHARACTERISTICS OF FREEZE-THAW DOUBLE-FISSURED GRANITE UNDER UNIAXIAL COMPRESSION

    • 摘要: 对于季冻区的岩体工程,岩石经常受到冻融和周期荷载扰动引起的耦合疲劳损伤。为了研究冻融裂隙花岗岩的疲劳开裂扩展情况,量化裂纹的损伤程度和分类类型,对冻融40次后的双裂隙花岗岩进行了3种应力振幅下的周期荷载试验。采用实时声发射和高速摄影监测技术来揭示裂纹演化,并进一步对不同的裂纹开裂类型进行分类,以帮助理解动态压裂规律,利用核磁共振测试分析裂隙花岗岩细观孔隙特征及其宏观力学特性的关系。结果表明:随着周期荷载振幅应力比的增加,双裂隙花岗岩在周期荷载“沉寂期”内的声发射计数增加;周期荷载阶段双裂隙花岗岩产生的剪切裂纹占比大于单调加载阶段,高振幅作用下岩石容易形成剪切破坏裂纹;双裂隙花岗岩声发射的最大幅值变小即大尺度破裂减少,周期荷载下岩样预制裂隙外尖端产生的向端面扩展裂纹的角度越大;双裂隙花岗岩的疲劳寿命减小,内部微裂隙扩展发育减缓,能够储存的含H流体也越少,最终表现为核磁共振T2谱面积变化率减小。

       

      Abstract: For rock mass engineering in frozen areas,rocks are often subjected to coupling fatigue damage caused by freeze-thaw cycles and periodic load disturbances. To study the fatigue cracking propagation of freeze-thaw fractured granite and quantify the degree of damage and classification types of cracks,three periodic load tests under stress amplitude were conducted on double-fractured granite after 40 freeze-thaw cycles. Real-time acoustic emission and high-speed photographic monitoring technology were employed to reveal crack evolution,and different crack cracking types were further classified to aid in understanding dynamic fracturing laws. Additionally,the relationship between mesoscopic pore characteristics and macroscopic mechanical properties of fractured granite was analyzed through nuclear magnetic resonance testing. The results demonstrate that with the increase in amplitude-stress ratio of the periodic load,the double-fractured granite experiences a "silent period" during the periodic load. The proportion of shear cracks generated by double-fractured granite during periodic loading stages is greater than that during monotonic loading stages,and the rock is prone to forming shear failure cracks under high amplitudes. Furthermore,the maximum value of acoustic emission from double-fractured granite decreases,indicating a decrease in large-scale fractures. Additionally,the angle of the extended crack to the end face of the outer tip of the prefabricated fracture of the rock sample is larger under periodic load. The fatigue life of double-fractured granite decreases,the development of internal microfracture propagation slows down,and the H-containing fluid that can be stored is also reduced,ultimately manifested as a decrease in the area change rate of the nuclear magnetic resonance T2 spectral area.

       

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