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煤岩孔裂隙结构特征对其损伤演化规律影响

赵怡晴, 秦文静, 金爱兵, 曹志国, 刘金博, 秦琨

赵怡晴,秦文静,金爱兵,等. 煤岩孔裂隙结构特征对其损伤演化规律影响[J]. 煤炭科学技术,2025,53(5):90−101. DOI: 10.12438/cst.2024-0153
引用本文: 赵怡晴,秦文静,金爱兵,等. 煤岩孔裂隙结构特征对其损伤演化规律影响[J]. 煤炭科学技术,2025,53(5):90−101. DOI: 10.12438/cst.2024-0153
ZHAO Yiqing,QIN Wenjing,JIN Aibing,et al. Influence of pore-fracture structure characteristics of coal rock on its damage evolution law[J]. Coal Science and Technology,2025,53(5):90−101. DOI: 10.12438/cst.2024-0153
Citation: ZHAO Yiqing,QIN Wenjing,JIN Aibing,et al. Influence of pore-fracture structure characteristics of coal rock on its damage evolution law[J]. Coal Science and Technology,2025,53(5):90−101. DOI: 10.12438/cst.2024-0153

煤岩孔裂隙结构特征对其损伤演化规律影响

基金项目: 

“煤炭开采水资源保护与利用”国家重点实验室 2017 开放基金资助项目(SHJT-17–42.1) ;“东部草原区大型煤电基地生态修复与综合整治技术与示范”国家重点研发计划资助项目(2016YFC0501100)

详细信息
    作者简介:

    赵怡晴: (1980—),女,四川南充人,教授,博士生导师,博士。E-mail:zyq@ustb.edu.cn

    通讯作者:

    金爱兵: (1974—),男,江苏兴化人,教授,博士生导师,博士。E-mail:jinaibing@ustb.edu.cn

  • 中图分类号: TD313

Influence of pore-fracture structure characteristics of coal rock on its damage evolution law

  • 摘要:

    煤岩孔裂隙发育扩展是造成煤岩损伤,从而导致瓦斯突出、冲击地压、煤柱失稳等矿山灾害的主要原因,探究煤岩压裂过程中裂隙破裂演化规律及煤岩损伤演化规律是预测煤岩动力灾害的前提。裂隙倾角分布、孔隙率为影响煤岩裂隙破裂规律的重要因素,采用单轴压缩、CT电子扫描和核磁共振试验对煤岩力学性能和孔裂隙结构进行分析,通过煤岩裂隙分形维数和裂隙倾角分布特征,表征煤岩内部裂隙结构;同时结合数值模拟对不同裂隙倾角煤岩裂隙扩展和损伤演化规律进行分析。研究结果表明:① 裂隙倾角分布特征为影响煤岩力学特性的主要因素,孔隙率为影响煤岩力学性质的次要因素。② 结合室内试验和数值模拟,单一裂隙煤岩抗压强度高于复杂裂隙煤岩抗压强度;且当煤岩裂隙倾角以单一裂隙为主时,急倾煤岩抗压强度>缓倾煤岩抗压强度>倾斜煤岩抗压强度。③ 单一裂隙煤岩相较于复杂裂隙煤岩,复杂程度较低,煤岩初始损伤较低,在裂纹加速扩展阶段,储存的应变能急速剧烈释放,宏观表现为破碎程度较高的剪切破坏。 ④ 基于裂隙发育数量建立包含峰后阶段的煤岩损伤变量,煤岩损伤演化过程呈指数型增长,分为近似无损、初始损伤、损伤稳定发展阶段、损伤加速发育阶段、残余损伤阶段,该损伤规律可为矿山灾害预测提供理论支撑。

    Abstract:

    The development and expansion of fractures in coal rocks are the primary causes of mining disasters, such as gas outbursts, rock bursts, and instability of coal pillars. Investigating the fracture evolution process and damage evolution law in coal rocks is crucial for predicting dynamic hazards in coal mines. Fracture inclination angle and porosity are significant factors influencing the propagation behavior of fractures in coal rocks. In this study, we conducted uniaxial compression tests, CT electron scanning, and nuclear magnetic resonance experiments to analyze the mechanical properties and pore-fracture structure of coal rocks. We characterized the fractal dimension of internal fractures in coal rocks by analyzing their distribution characteristics along with fracture inclination angles. Additionally, numerical simulations were employed to analyze the propagation and damage evolution laws of fractures with different inclination angles in coal rocks. The research findings demonstrate that: ① The degree and distribution characteristics of fracture inclination angles significantly impact the complexity and fracturing behavior of coal rock; when a single dominant fracture exists, steeply inclined coal rock exhibits higher compressive strength compared to gently inclined or nearly vertical ones; compressive strength is higher for single-fractured coals than complex-fractured ones. ② Porosity is the primary factor influencing the compressive strength of coal rock of the same type. As porosity increases, the compressive strength of coal rock decreases and exhibits a direct correlation with the presence of large pores. ③ Single-fracture coal and rock exhibit a lower level of complexity compared to complex fractured ones. This results in reduced stress concentration during compression, leading to less initial damage. However, during accelerated crack propagation, there is a rapid release of stored strain energy, resulting in higher levels of shear failure. ④ By establishing a variable for coal and rock damage based on the number of developed fractures, it can be observed that the evolution process follows an exponential growth pattern. This process can be divided into stages including approximate intactness, initial damage, stable development of damage, accelerated development of damage, and residual damage. Such observations provide theoretical support for predicting mining disasters.

  • 图  1   煤岩试样

    Figure  1.   Coal samples

    图  2   高分辨X射线三维扫描成像系统

    Figure  2.   High resolution X-ray three-dimensional scanning imaging system

    图  3   核磁共振实验设备

    Figure  3.   NMR test process

    图  4   3组不同裂隙煤样的三维重构模型

    Figure  4.   Three-dimensional reconstruction model of three groups coal samples

    图  5   煤样倾角分布图及三维剖析

    Figure  5.   Distribution diagram and three-dimensional analysis diagram of coal sample inclination angle

    图  6   煤样孔径占比分布

    Figure  6.   Distribution map of coal sample pore size proportion

    图  7   煤样力学性质数据曲线

    Figure  7.   Coal sample mechanical property data curves

    图  8   数值模拟与室内试验结果对比

    Figure  8.   Comparison between numerical simulation and indoor test results

    图  9   数值模拟应力应变、裂隙发育趋势曲线

    Figure  9.   Numerical simulation stress-strain and fracture development trend curves

    图  10   煤岩裂纹数量–损伤变化

    Figure  10.   Coal rock crack quantity damage variation chart

    表  1   2组煤样的裂隙结构统计

    Table  1   Statistical analysis of fracture structures in two sets of coal samples

    类型编号分形维数裂隙体积分数
    A组(单一裂隙煤岩)1–32.200.42
    B组(复杂裂隙煤岩)2–12.270.40
    2–22.230.36
    下载: 导出CSV

    表  2   2组煤样的裂隙倾角分布

    Table  2   Distribution characteristics of fracture dip angles in two sets of coal samples

    1–3 2–1 2–2
    倾角类型 倾角范围/(°) 体积占比/% 倾角类型 倾角范围/(°) 体积占比/% 倾角类型 倾角范围/(°) 体积占比/%
    缓倾 0~10 50.78% 缓倾 0–10° 17.91% 缓倾 0–10° 19.91%
    10~20 32.67% 10–20° 24.06% 10–20° 21.03%
    20~30 3.61% 20–30° 1.75% 20–30° 9.93%
    倾斜 30~40 3.57% 倾斜 30–40° 3.20% 倾斜 30–40° 3.51%
    40~50 0.43% 40–50° 0.74% 40–50° 1.14%
    50~60 0.80% 50–60° 51.00% 50–60° 42.23%
    急倾 60~70 7.02% 急倾 60–70° 0.71% 急倾 60–70° 1.79%
    80~90 1.12% 80–90° 0.63% 80–90° 0.45%
    下载: 导出CSV

    表  3   煤样孔隙率统计

    Table  3   Statistics of coal sample porosity

    类型 编号 孔隙率/% 平均孔隙率/% 孔径分布占比/%
    r<0.3 μm 0.3 ≤r<3 μm r≥3 μm
    单一裂隙煤岩 1–1 17.98 18.26 0.968 0.032 0.001
    1–2 18.15 0.895 0.101 0.003
    1–3 18.66 0.948 0.049 0.002
    复杂裂隙煤岩 2–1 14.78 15.09 0.925 0.066 0.009
    2–2 14.98 0.916 0.073 0.011
    2–3 14.38 0.935 0.059 0.005
    2–4 14.92 0.943 0.054 0.003
    2–5 15.74 0.903 0.087 0.010
    2–6 15.77 0.907 0.085 0.008
    下载: 导出CSV

    表  4   煤样单轴压缩测试结果

    Table  4   Uniaxial compression test results of coal samples

    类型 编号 主要倾角 孔隙率/% 孔隙率均值/% σc/MPa σc均值/MPa E/GPa E均值/GPa
    A单一裂隙煤岩 1–1 缓倾 17.98 18.26 35.04 35.48 1.79 1.79
    1–2 18.15 14.28 1.34
    1–3 18.66 35.91 1.79
    B复杂裂隙煤岩 2–1 2种以上主要倾角 14.78 15.09 19.85 20.25 1.54 1.72
    2–2 14.98 17.71 1.62
    2–3 14.38 22.27 1.60
    2–4 14.92 22.18 1.84
    2–5 15.74 17.08 1.71
    2–6 15.77 22.39 2.01
    下载: 导出CSV

    表  5   数值模拟参数

    Table  5   Numerical simulation parameters

    PFC3D数值模型细观参数 煤岩数值
    deformemod 1.2×109
    krat 1.0
    pb_deformemod 1.2×109
    krat 4.9
    pb_ten 40.2×106
    pb_coh 40.2×106
    下载: 导出CSV

    表  6   数值模拟单轴压缩测试结果

    Table  6   Numerical simulation uniaxial compression test results

    类型 编号 缓倾占比/% 倾斜占比/% 急倾占比/% 抗压强度/MPa
    单一裂隙煤岩 A'–1 87.06 6.47 6.47 35.20
    A'–2 6.47 87.06 6.47 32.08
    A'–3 6.47 6.47 87.06 54.55
    复杂裂隙煤岩 B'–1 49 49 2 19.14
    B'–2 49 2 49 24.47
    B'–3 2 49 49 30.22
    下载: 导出CSV
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