| 三轴疲劳-卸围压条件下大理岩力学特性试验研究 |
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| 引用本文： | 侯志强,王宇,刘冬桥,李长洪,刘昊.三轴疲劳-卸围压条件下大理岩力学特性试验研究[J].岩土力学,2020,41(5):1510-1520. |
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| 作者姓名： | 侯志强 王宇 刘冬桥 李长洪 刘昊 |
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| 作者单位： | 1. 北京科技大学 土木与资源工程学院，北京 100083；
2. 中国矿业大学（北京） 深部岩土力学与地下工程国家重点实验室，北京 100083 |
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| 基金项目： | 国家重点研发计划资助项目（No. 2018YFC0808402）；中国矿业大学（北京）深部岩土力学与地下工程国家重点实验室开放基金课题 （No. SKLGDUEK1824）；中央高校基本科研业务费专项资金资助（No. FRF-TP-20-004A2） |
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| 摘 要： | 为了揭示应力扰动和卸载围压作用下大理岩损伤破裂的物理过程和非线性力学行为，采用GCTS RTR-2000伺服加载岩石力学试验机进行了岩石疲劳卸围压试验，同时对破坏试样进行了压后裂纹形态CT扫描可视化分析。结果表明：周期性的加卸载作用对大理岩起到了主因损伤作用，卸围压的作用对大理岩起到了根本性的破坏作用。岩石疲劳循环形成滞回环，滞回环面积由疏变密，滞回环加载和卸载曲线接近重合，加卸载模量近似相等；岩石经过卸围压作用，岩石的轴向、径向和体积应变表现为不同程度增大，表明应变对围压降低具有强敏感性，敏感程度由高到低依次为体积应变、径向应变和轴向应变；由于疲劳循环的影响，卸围压作用产生的围压降幅随循环次数增多而降低，卸围压时长随循环次数增多而减少；量化宏观应变变形，求得应变损伤指数 、 、 ，疲劳循环次数越多，应变损伤指数越大；岩石破坏后细观CT扫描揭示了疲劳循环损伤对岩石破裂形态影响的内在机制。随疲劳循环次数的增加，裂纹密度和规模显著增加。研究成果可为地下工程疲劳活动规律和开挖卸荷问题提供理论和模型支撑。
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| 关 键 词： | 三轴压缩 疲劳荷载 卸围压 应力-应变特征 CT扫描 |
| 收稿时间： | 2019-05-29 |
| 修稿时间： | 2019-09-08 |
Experimental study of mechanical properties of marble under triaxial
unloading confining pressure after fatigue loading |
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| HOU Zhi-qiang,WANG Yu,LIU Dong-qiao,LI Chang-hong,LIU Hao.Experimental study of mechanical properties of marble under triaxial
unloading confining pressure after fatigue loading[J].Rock and Soil Mechanics,2020,41(5):1510-1520. |
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| Authors: | HOU Zhi-qiang WANG Yu LIU Dong-qiao LI Chang-hong LIU Hao |
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| Institution: | 1. School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China |
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| Abstract: | To reveal the physical process and nonlinear mechanical behaviour of rock failure under stress disturbance and unloading confining pressure, the fatigue and triaxial unloading confining pressure tests were carried out on marble by using GCTS RTR-2000 servo loading testing machine. Moreover, the X-ray computed tomography (CT) was applied for the visualisation analysis of crack morphology of damaged specimens after compression. The results show that periodic loading and unloading play a significant role in damage, while unloading confining pressure dominantly control the failure of marble. Rock fatigue cycles form hysteretic loops, and the areas of hysteretic loops change from sparse to dense. Loading and unloading curves of hysteretic loops coincide well with each other, and the modulus values at loading and unloading stages are approximately equal. After unloading confining pressure, the axial, radial and volumetric strains of marble increase in varying degrees, indicating that the strain is highly sensitive to the unloading confining pressure, and the sensitivity degrees of volumetric, radial and axial strains are from high to low. Due to the influence of fatigue cycle, both the drop of confining pressure caused by unloading confining pressure and the unloading period of confining pressure decrease with the increase of cycle number. To quantify the macroscopic deformation, the strain damage indices , and are obtained. The more the number of periodic cycles, the higher the strain damage index. The microscopic CT scan after rock failure reveals the internal mechanism of the effect of fatigue cycle on fracture morphology, and the crack density and size increase with the increase of fatigue number. The results can provide theoretical and model support for fatigue activity and unloading excavation of underground engineering. |
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| Keywords: | triaxial compression fatigue load unloading confining pressure stress-strain characteristics CT scan |
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