不同加载速率下砂岩弯曲破坏的细观机理

李柯萱 李铁

李柯萱, 李铁. 不同加载速率下砂岩弯曲破坏的细观机理[J]. 爆炸与冲击, 2019, 39(4): 043101. doi: 10.11883/bzycj-2018-0178
引用本文: 李柯萱, 李铁. 不同加载速率下砂岩弯曲破坏的细观机理[J]. 爆炸与冲击, 2019, 39(4): 043101. doi: 10.11883/bzycj-2018-0178
LI Kexuan, LI Tie. Micro-mechanism of bending failure of sandstone under different loading rates[J]. Explosion And Shock Waves, 2019, 39(4): 043101. doi: 10.11883/bzycj-2018-0178
Citation: LI Kexuan, LI Tie. Micro-mechanism of bending failure of sandstone under different loading rates[J]. Explosion And Shock Waves, 2019, 39(4): 043101. doi: 10.11883/bzycj-2018-0178

不同加载速率下砂岩弯曲破坏的细观机理

doi: 10.11883/bzycj-2018-0178
基金项目: 国家自然科学基金(51674016,51274025,51534002)
详细信息
    作者简介:

    李柯萱(1987- ),女,博士研究生, likexuan_456@163.com

    通讯作者:

    李 铁(1956- ),男,博士,教授,litie@ustb.edu.cn

  • 中图分类号: O348.3; TU454

Micro-mechanism of bending failure of sandstone under different loading rates

  • 摘要: 岩石细观破裂形貌是岩石破坏机制的重要反映,为研究不同加载速率对砂岩弯曲破坏的影响,通过三点弯曲实验和扫描电镜方法,对某煤矿关键层砂岩弯曲破断裂纹细观形态以及裂纹的自相似性进行了研究。选取6个不同加载速率对岩样进行三点弯曲实验,观察其宏观断裂情况,并利用扫描电镜对弯曲断裂面表面裂纹细观结构进行观察,并拍摄不同倍数下的扫描电镜图片。对图片进行图像处理后得到砂岩弯曲断裂破坏细观裂纹信息,并计算得到微裂纹的分形盒维数值。结果显示:随着加载速率的提高,砂岩穿晶断裂的比例也随之升高,裂纹分形维数亦随着加载速率的增大而增加,同时,分形维数还与弯曲断裂破坏荷载和抗弯强度成正比。可见,加载速率对断裂方式有一定的影响,且加载速率越大断裂所需的破坏能越大,裂纹分布越广,表明开采速度与岩爆等岩体动力灾变有密切关系。
  • 图  1  破坏荷载的加载速率效应

    Figure  1.  Loading rate effect of failure load

    图  2  0.1、10和60 N/s加载速率下样品破坏照片

    Figure  2.  Specimen destruction under loading rates of 0.1, 10 and 60 N/s

    图  3  不同加载速率下样品的SEM图像

    Figure  3.  SEM images of samples at different loading rates

    图  4  SEM图像裂纹图像提取过程

    Figure  4.  Crack image extraction process of SEM photos

    图  5  分形盒维数法计算

    Figure  5.  Fractal dimension calculation in box counting

    图  6  加载速率和分形维数之间的关系

    Figure  6.  Relationship between fractal dimension and loading rate

    图  7  破坏荷载(Pt)、抗弯强度(Rt)与分形维数(Ds)的关系

    Figure  7.  Variation of failure load (Pt) and bending strength (Rt) with fractal dimension (Ds)

    表  1  岩石三点弯曲实验力学参数

    Table  1.   Mechanical parameters of rock three-point bending testing

    加载速率/(N·s−1) 编号 破坏荷载/kN 抗弯强度/MPa 加载速率/(N·s−1) 编号 破坏荷载/kN 抗弯强度/MPa
    0.1 A1 2.5 10 D1 2.86
    A2 2.61 D2 2.51
    A3 2.57 D3 2.94
    平均 2.56 6.144 D4 3.00
    0.4 B1 2.58 平均 2.93 7.032
    B2 2.72 30 E1 3.34
    B3 2.68 E2 3.25
    平均 2.66 6.384 E3 3.47
    1 C1 2.8 平均 3.35 8.040
    C2 2.99 60 F1 3.64
    C3 2.83 F2 3.48
    C4 2.71 F3 3.63
    平均 2.78 6.648 平均 3.56 8.544
    下载: 导出CSV

    表  2  砂岩试件裂纹分形维数

    Table  2.   Fractal dimension of cracks of sandstone

    加载速率/(N·s−1) 拟合公式 分形维数 加载速率/(N·s−1) 拟合公式 分形维数
    0.1 log2N=−1.670 1 log2a+2.696 6 1.670 1 10 log2N=−1.717 7 log2a+3.177 6 1.717 7
    log2N=−1.665 3 log2a+3.002 6 1.665 3 log2N=−1.699 9 log2a+2.316 7 1.699 9
    log2N=−1.699 2 log2a+2.737 6 1.699 2 log2N=−1.705 5 log2a+2.981 5 1.705 5
    平均 1.678 2 平均 1.707 7
    0.4 log2N=−1.671 6 log2a+3.257 5 1.671 6 30 log2N=−1.736 6 log2a+3.097 9 1.736 6
    log2N=−1.683 5 log2a+2.798 7 1.683 5 log2N=−1.725 8 log2a+3.011 8 1.725 8
    log2N=−1.692 7 log2a+3.127 6 1.692 7 log2N=−1.742 6 log2a+3.328 6 1. 742 6
    平均 1.682 6 平均 1.735
    1 log2N=−1.698 7 log2a+3.315 7 1.698 7 60 log2N=−1.762 9 log2a+2.923 0 1.762 9
    log2N=−1.696 8 log2a+3.255 3 1.696 8 log2N=−1.749 8 log2a+3.257 4 1.749 8
    log2N=−1.703 6 log2a+2.446 0 1. 703 6 log2N=−1.764 6 log2a+2.986 6 1.764 6
    平均 1.699 7 平均 1.759 1
    下载: 导出CSV
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出版历程
  • 收稿日期:  2018-05-25
  • 修回日期:  2018-08-27
  • 刊出日期:  2019-04-01

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