使用声发射和诊断成像表征三轴压缩下 Montney 粉砂岩的损伤过程,Geophysical Journal International

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使用声发射和诊断成像表征三轴压缩下 Montney 粉砂岩的损伤过程
Geophysical Journal International ( IF 2.8 ) Pub Date : 2021-11-01 , DOI: 10.1093/gji/ggab455
Suzie Q Jia ₁ , Ron C K Wong ₁ , David W Eaton ₂

Affiliation

总结使用组合诊断技术，包括超声波测量、声发射 (AE) 监测、计算机断层扫描 (CT) 扫描和薄层截面成像。样品在失效前显示出弱到中度的固有地震各向异性和明显的应力诱导各向异性。在施加的轴向应力达到峰值的 95% 之前，没有检测到 AE 事件。然而，信噪比相对较低，可检测到的 AE 事件比在高脆性岩石中观察到的更分散。AE 位置与 CT 扫描成像的剪切断裂带相关。AE 力矩张量分析表明，具有较大相对量级的事件以高体积（拉伸或压缩）分量为特征，并且破坏区的起始以组合剪切拉伸 (ST) 破坏为主。具有高拉伸分量的 AE 事件的应力反转与已知的施加应力非常吻合。来自失效样品的薄片的显微成像表明，失效区是一个梯形结构，由带有分支微裂纹和小裂纹的主要裂缝组成。这种破坏机制与 ST 源机制一致，并被解释为与 Montney 粉砂岩的细粒结构和矿物组成有关。并且破坏区的起始以组合剪切-拉伸（ST）破坏为主。具有高拉伸分量的 AE 事件的应力反转与已知的施加应力非常吻合。来自失效样品的薄片的显微成像表明，失效区是一个梯形结构，由带有分支微裂纹和小裂纹的主要裂缝组成。这种破坏机制与 ST 源机制一致，并被解释为与 Montney 粉砂岩的细粒结构和矿物组成有关。并且破坏区的起始以组合剪切-拉伸（ST）破坏为主。具有高拉伸分量的 AE 事件的应力反转与已知的施加应力非常吻合。来自失效样品的薄片的显微成像表明，失效区是一个梯形结构，由带有分支微裂纹和小裂纹的主要裂缝组成。这种破坏机制与 ST 源机制一致，并被解释为与 Montney 粉砂岩的细粒结构和矿物组成有关。来自失效样品的薄片的显微成像表明，失效区是一个梯形结构，由带有分支微裂纹和小裂纹的主要裂缝组成。这种破坏机制与 ST 源机制一致，并被解释为与 Montney 粉砂岩的细粒结构和矿物组成有关。来自失效样品的薄片的显微成像表明，失效区是一个梯形结构，由带有分支微裂纹和小裂纹的主要裂缝组成。这种破坏机制与 ST 源机制一致，并被解释为与 Montney 粉砂岩的细粒结构和矿物组成有关。

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Characterization of damage processes in Montney siltstone under triaxial compression using acoustic emission and diagnostic imaging

SUMMARY Crack nucleation and rock failure processes in a fine-grained siltstone (Montney Formation) under triaxial compression are investigated using combined diagnostic techniques, including ultrasonic-wave measurement, acoustic-emission (AE) monitoring, computed tomography (CT) scanning, and thin-section imaging. The sample displays a weak-to-moderate inherent seismic anisotropy and noticeable stress-induced anisotropy prior to failure. No AE event was detected until the applied axial stress reached 95 per cent of the peak value. The signal-to-noise ratio is relatively low, however, and detectable AE events are more diffuse than those observed in highly brittle rocks. The AE locations correlate with a shear fracture zone imaged by CT scanning. AE moment-tensor analysis reveals that events with larger relative magnitudes are characterized by high volumetric (tensile or compressive) components, and the initiation of the failure zone is dominated by combined shear-tensile (ST) failure. Stress inversion of the AE events with high tensile components is in good agreement with the known applied stress. Microscopic imaging of thin sections from the failed sample shows that the failure zone is an en echelon structure consisting of a major fracture with branching micro and minor cracks. This failure mechanism is consistent with a ST source mechanism and is interpreted to be associated with the fine granular structure and mineral composition of Montney siltstone.

更新日期：2021-11-01

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