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蔡燕燕, 唐欣, 林立华, 陈华龙, 高海东, 李刚, 俞缙. 疲劳荷载下大理岩累积损伤过程的应变速率响应[J]. 岩土工程学报, 2020, 42(5): 827-836. DOI: 10.11779/CJGE202005004
引用本文: 蔡燕燕, 唐欣, 林立华, 陈华龙, 高海东, 李刚, 俞缙. 疲劳荷载下大理岩累积损伤过程的应变速率响应[J]. 岩土工程学报, 2020, 42(5): 827-836. DOI: 10.11779/CJGE202005004
CAI Yan-yan, TANG Xin, LIN Li-hua, CHEN Hua-long, GAO Hai-dong, LI Gang, YU Jin. Strain rate response of damage accumulation of marble under fatigue loading[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(5): 827-836. DOI: 10.11779/CJGE202005004
Citation: CAI Yan-yan, TANG Xin, LIN Li-hua, CHEN Hua-long, GAO Hai-dong, LI Gang, YU Jin. Strain rate response of damage accumulation of marble under fatigue loading[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(5): 827-836. DOI: 10.11779/CJGE202005004

疲劳荷载下大理岩累积损伤过程的应变速率响应

Strain rate response of damage accumulation of marble under fatigue loading

  • 摘要: 通过不同围压下4种应力比进行应力控制的大理岩等幅循环加卸载三轴压缩试验,探索疲劳荷载作用下岩石累积损伤过程中的应变速率响应特征。结果表明:①在低围压或高应力比条件下岩样易发生疲劳破坏。随循环次数增加,发生疲劳破坏岩样的弹性模量呈急速下降趋势,未发生疲劳破坏岩样的弹性模量小幅波动后趋稳。②加载过程中岩样轴向应变速率随应变发展呈“U”型演化趋势,体变速率随体变发展呈反“L”型演化趋势,临近破坏时轴向应变速率和体变速率均大幅增加。卸载过程中轴向应变速率呈倒“S”型演化规律,体变速率呈“U”型演化趋势。③每次加载的初始和终了应变速率各自均与其对应的残余应变呈线性正相关关系,当次加载的初始应变速率可反映岩样在之前疲劳作用下的累积损伤程度。④新建立的归一化初始应变速率和损伤因子有明显的线性关系,系数K随围压增大或应力比值减小而减小。未破坏岩样在后期循环加载时的归一化初始应变速率和损伤因子曲线出现“弯钩”型回缩现象。

     

    Abstract: The cyclic loading experiments, in which the constant amplitude cyclic loading and unloading are imposed at different stress levels, are carried out on marble samples under various confining pressures to study the effects of fatigue loading conditions on mechanical properties of rock. The results show that: (1) The rock samples are mostly like to be destroyed under high stress ratio or low confining pressure. The elastic modulus of the damaged rock samples decreases rapidly with the increase of the number of fatigue cycles, while the elastic modulus of the undamaged samples fluctuates slightly with the increase of the number of cycles before the final stabilization. (2) The axial strain rate evolution of the rock samples shows a "U" type trend with the strain development during loading. And the volume strain rate shows an inverted "L" type trend with the volume change. Both strain rates increase remarkably when the samples approach failure. During unloading, the axial strain rate evolution shows an inverted "S" shape, and the volume strain rate shows a "U" type trend. (3) At the beginning and ending stages, the strain rate exhibits positive correlation with the residual stress. The initial strain rate reflects the accumulated damage of rock samples under the previous fatigue effect. (4) After the normalization of axial strain rate at the initial stage, there is an obvious linear relationship between the axial strain rate and the damage factor, and the coefficient K decreases with the increase of confining pressure or the decrease of stress ratio. The evolution of the cyclic normalized axial strain rate and damage factor of the undamaged rock samples retracts as a hook type.

     

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