Stress Dependency of Brittle Creep in Granite: Insights into Source Mechanisms and Parameters

Journal Article · Mon Aug 05 00:00:00 EDT 2024 · Rock Mechanics and Rock Engineering

DOI:https://doi.org/10.1007/s00603-024-04097-w· OSTI ID:2465110

Zafar, Sana ^[1]; Hedayat, Ahmadreza ^[2]; Moradian, Omid ^[2]

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1. Colorado School of Mines, Golden, CO (United States); Stantec USA, Chicago, IL (United States); Colorado School of Mines
2. Colorado School of Mines, Golden, CO (United States)

Creep in rocks refers to the gradual deformation of rock material over time under the influence of constant stress. Characterizing these deformations is of great importance for engineering design, geotechnical assessment, mining operations, geological studies, and understanding natural hazards. While laboratory experiments and a variety of numerical approaches have offered explanations for microcrack interaction and damage accumulation under the three stages of creep (primary, secondary and tertiary) in conventional creep experiments, the micromechanisms of the fractures produced in brittle creep and its dependency on the applied stress have not been explored in detail. The present study focused on investigating the fracturing mechanisms that occur during creep-induced fracturing at different stress levels and estimation of the source parameters and energy budget components. A series of uniaxial compression creep experiments have been conducted at different stress level ratios (70%, 75%, 80% and 85%), to the unconfined compressive strength (UCS) of double-flawed Barre granite specimen. Creep measurements were complemented with the Acoustic Emission (AE) measurements. The creep-induced fractures were classified into double-couple (DC), compensated linear vector dipole (CLVD) and isotropic (ISO) components using the AE moment tensor decomposition technique. The results show that non-double-couple sources dominated during creep at all the specified stress levels; however, their proportions decreased as the stress level was increased. The source parameters estimation indicated a significant increase in the magnitude of the events and the radiated seismic energy with increasing levels of stress and a slight increase in the evaluated source radius and stress drop with increasing stress levels. Furthermore, this study contributes to the existing knowledge of creep-induced fracturing by providing insights into the fracturing mechanisms and the radiated seismic energy produced, which can be helpful for the development of improved models and strategies for rock engineering and geoscience applications.

• Research Organization: Colorado School of Mines, Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Engineering & Technology
• Grant/Contract Number: SC0019117
• OSTI ID: 2465110
• Journal Information: Rock Mechanics and Rock Engineering, Journal Name: Rock Mechanics and Rock Engineering Journal Issue: 12 Vol. 57; ISSN 0723-2632
• Publisher: Springer
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
Barre granite
Creep
Energy budget
Seismic source parameters
Source mechanisms