Moment tensor and stress inversion solutions of acoustic emissions during compression and tensile fracturing in crystalline rocks
作者机构：Department of Earth SciencesSwiss Federal Institute of Technology(ETH)Zurich8006Switzerland Department of Civil and Environmental EngineeringWestern UniversityLondonONN6A 3K7Canada Department of Civil and Environmental EngineeringColorado School of MinesGoldenCO80401USA
出 版 物：《Journal of Rock Mechanics and Geotechnical Engineering》 (岩石力学与岩土工程学报(英文版))
年 卷 期：2023年第15卷第10期
页 面：2778-2786页
核心收录：
学科分类：07[理学] 0818[工学-地质资源与地质工程] 0701[理学-数学]
基 金：Swiss Federal Institute of Technology Eidgenössische Technische Hochschule Zürich, ETH
主 题：Induced seismicity Acoustic emission(AE) Moment tensor(MT)inversion Stress inversion Finite element(FE)modeling
摘 要：We investigate the accuracy and robustness of moment tensor(MT)and stress inversion solutions derived from acoustic emissions(AEs)during the laboratory fracturing of prismatic Barre granite specimens.Pre-cut flaws in the specimens introduce a complex stress field,resulting in a spatial and temporal variation of focal mechanisms.Specifically,we consider two experimental setups:(1)where the rock is loaded in compression to generate primarily shear-type fractures and(2)where the material is loaded in indirect tension to generate predominantly tensile-type fractures.In each test,we first decompose AE moment tensors into double-couple(DC)and non-DC terms and then derive unambiguous normal and slip vectors using k-means clustering and an unstructured damped stress inversion algorithm.We explore temporal and spatial distributions of DC and non-DC events at different loading levels.The majority of the DC and the tensile non-DC events cluster around the pre-cut flaws,where macro-cracks later develop.Results of stress inversion are verified against the stress field from finite element(FE)modeling.A good agreement is found between the experimentally derived and numerically simulated stress orientations.To the best of the authors’knowledge,this work presents the first case where stress inversion methodologies are validated by numerical simulations at laboratory scale and under highly heterogeneous stress distributions.
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