Geomechanics and Geophysics for Geo-Energy and Geo-Resources ( IF 3.9 ) Pub Date : 2021-05-20 , DOI: 10.1007/s40948-021-00254-5 Zhenlong Ge , Qiang Sun , Lei Xue , Shaofei Wang
Abstract
Determining rock damage thresholds is of great significance in predicting rock fracture. In this study, the relation among crack damage stress threshold (σcd), peak strength (σucs) and shape parameter m was observed. The impact imposed by temperature and confining pressure on m was then examined. The results show that there is an approximate linear relationship between σcd and σucs. Therefore, the normalized quantity σcd/σucs is considered one quantitative indicator useful in evaluating rock damage. The research performed uniaxial compression tests on gabbro specimens heated using microwaves. It is found that σucs and σcd decrease gradually with increases in irradiation energy for gabbro samples; with identical irradiation energy, higher heating power leads to faster decrease of m. We also collected data from previous studies on igneous rock damage. It is found that, with increases in m, σcd/σucs increases, but overall, the ratio is not sensitive to m and m is primarily distributed between 1 and 4; further, m decreases with increases in temperature—at 600 °C and 800 °C, m decreases significantly, which has close connections with quartz phase transition. Subject to low confining pressure, m grows as confining pressure grows. If the confining pressure rises beyond 40 MPa, the plastic characteristics of the rock are enhanced which causes m to decrease.
Article Highlights
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For gabbro samples heated by microwaves, as irradiation energy increases, both σucs and σcd progressively reduce. Subject to the identical irradiation energy, higher heating power results in faster decrease in the value of m.
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The value of σcd/σucs increases with shape parameter m, but overall, the ratio is not sensitive to m and m is primarily distributed between 1 and 4.
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For different types of igneous rock samples, m decreases with increases in temperature. In particular, at 600 °C and 800 °C, the m decreases significantly.
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Under low confining pressure, m increases as confining pressure increases. As long as the confining pressure surmounts 40 MPa, the plastic characteristics of the rock are enhanced and the m begins to decrease.
中文翻译：
温度和围压对火成岩裂缝破坏阈值和形状参数m的影响
摘要
确定岩石破坏阈值对于预测岩石破裂具有重要意义。在这项研究中，除裂纹损伤应力阈值（的关系σ CD），峰强度（σ UCS）和形状参数米进行了观察。然后检查了温度和围压对m的影响。结果表明，存在之间的近似线性关系σ CD和σ UCS。因此，归一化的量σ CD / σ UCS被认为是一种可用于评估岩石破坏的定量指标。该研究对用微波加热的辉长岩样品进行了单轴压缩试验。据发现，σ UCS和σ CD逐渐减小，在照射能量为增加辉长岩样品; 在相同的照射能量下，较高的加热功率会导致m的更快减小。我们还从以前关于火成岩破坏的研究中收集了数据。据发现，与在增加米，σ CD / σ UCS增加，但总体来说，该比率不敏感米和米主要分布在1和4之间；此外，m随着温度的升高而降低，在600°C和800°C时，m显着降低，这与石英相变有着密切的联系。在较低的围压下，m随围压的增长而增长。如果围压升高到40 MPa以上，岩石的塑性特性会增强，从而导致m减小。
文章重点
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对于通过微波加热辉长岩样品，作为照射能量增加时，既σ UCS和σ CD逐步减少。在相同的照射能量下，较高的加热功率导致m值更快地减小。
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的值σ CD / σ UCS与形状参数增加米，但总体来说，该比率不敏感米和米是1和4之间，主要分布。
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对于不同类型的火成岩样品，m随着温度的升高而减小。特别地，在600℃和800℃下，m显着降低。
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在低围压下，m随着围压的增加而增加。只要围压超过40 MPa，岩石的塑性特征就会增强，m会开始下降。
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