Scholarlink

<p>Understanding the evolution of micro-cracks and the timing of failure in brittle rocks is crucial for comprehending catastrophic macroscopic failure mechanisms and extending the safe service life of rock structures. This is particularly significant in shale oil and gas extraction and engineering design, where the formation and propagation of micro-cracks directly impact operational safety and production efficiency. This study employed time-lapse X-ray computed tomography (CT) to conduct in-situ compression tests on shale samples, investigating the effects of loading rates (<i>v</i> = 0.3, 2, and 4&#xa0;μm/s) on the mechanical performance and cracking behavior of shale. By capturing high-resolution CT images of shale under different deformation stages in real time, the nucleation, growth, and coalescence of micro-cracks during loading were precisely observed and quantitatively evaluated. The results demonstrated that loading rates significantly influenced the peak strength (<i>F</i>) and failure time (<i>t</i><sub><i>f</i></sub>) of shale. At lower loading rates (<i>v</i> = 0.3&#xa0;μm/s), the initial void closure rate within shale was slower, leading to a delayed cracking process and ultimately resulting in lower peak strength (<i>F</i> = 102 N) and later failure (<i>t</i><sub><i>f</i></sub> = 30.8&#xa0;min). Conversely, higher loading rates (<i>v</i> = 2&#xa0;μm/s) caused earlier pore closure, triggering rapid crack propagation along preferential orientations, resulting in higher peak strength (<i>F</i> = 141N) and quicker failure (<i>t</i><sub><i>f</i></sub> = 3.1&#xa0;min). The relationship between loading rate and failure time was found to follow an inverse exponential trend: <i>t</i><sub><i>f</i></sub> = 10.53 × <i>v</i><sup>−0.94</sup>. The cracking behavior and failure modes of shale were primarily governed by the initial pore structure and the distribution of pyrite, with the spatial arrangement of pyrite being a critical factor in crack nucleation and propagation along edges, ultimately leading to final failure. These findings enhance our understanding of shale fracturing behavior and provide scientific insights for predicting and preventing potential catastrophic failures in shale formations.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Effects of Loading Rate on Catastrophic Rock Failure: How and When? Insights from 4D In-Situ Compression Experiments on Shale Samples

  • 期刊论文

  • 发表日期：

    2025年4月7日

查看全文
  • Yulong Shao,
  • Qi Zhao,
  • Cancan Liu,
  • Seyedahmad Mehrishal,
  • Jae-Joon Song

摘要

Understanding the evolution of micro-cracks and the timing of failure in brittle rocks is crucial for comprehending catastrophic macroscopic failure mechanisms and extending the safe service life of rock structures. This is particularly significant in shale oil and gas extraction and engineering design, where the formation and propagation of micro-cracks directly impact operational safety and production efficiency. This study employed time-lapse X-ray computed tomography (CT) to conduct in-situ compression tests on shale samples, investigating the effects of loading rates (v = 0.3, 2, and 4 μm/s) on the mechanical performance and cracking behavior of shale. By capturing high-resolution CT images of shale under different deformation stages in real time, the nucleation, growth, and coalescence of micro-cracks during loading were precisely observed and quantitatively evaluated. The results demonstrated that loading rates significantly influenced the peak strength (F) and failure time (tf) of shale. At lower loading rates (v = 0.3 μm/s), the initial void closure rate within shale was slower, leading to a delayed cracking process and ultimately resulting in lower peak strength (F = 102 N) and later failure (tf = 30.8 min). Conversely, higher loading rates (v = 2 μm/s) caused earlier pore closure, triggering rapid crack propagation along preferential orientations, resulting in higher peak strength (F = 141N) and quicker failure (tf = 3.1 min). The relationship between loading rate and failure time was found to follow an inverse exponential trend: tf = 10.53 × v−0.94. The cracking behavior and failure modes of shale were primarily governed by the initial pore structure and the distribution of pyrite, with the spatial arrangement of pyrite being a critical factor in crack nucleation and propagation along edges, ultimately leading to final failure. These findings enhance our understanding of shale fracturing behavior and provide scientific insights for predicting and preventing potential catastrophic failures in shale formations.