Mechanical behaviors of granite after thermal treatment under loading and unloading conditions
- Understanding the mechanical behaviors of granite after thermal treatment under loading and unloading conditions is of utmost relevance to deep geothermal energy recovery. In the present study, a series of loading and unloading triaxial compression tests (20, 40 and 60 MPa) on granite specimens after exposure to different temperatures (20, 200, 300, 400, 500 and 600 degrees C) was carried out to quantify the combined effects of thermal treatment and loading/unloading stress conditions on granite strength and deformation. Changes in the microstructure of granite exposed to high temperatures were revealed by optical microscopy. The experimental results indicate that both, thermal treatment and loading/unloading stress conditions, degrade the mechanical behaviors and further decrease the carrying capacity of granite. The gradual degradation of the mechanical characteristics of granite after thermal treatment is mainly associated with the evolution of thermal micro-cracks based on optical microscopy observations. The unloading stressUnderstanding the mechanical behaviors of granite after thermal treatment under loading and unloading conditions is of utmost relevance to deep geothermal energy recovery. In the present study, a series of loading and unloading triaxial compression tests (20, 40 and 60 MPa) on granite specimens after exposure to different temperatures (20, 200, 300, 400, 500 and 600 degrees C) was carried out to quantify the combined effects of thermal treatment and loading/unloading stress conditions on granite strength and deformation. Changes in the microstructure of granite exposed to high temperatures were revealed by optical microscopy. The experimental results indicate that both, thermal treatment and loading/unloading stress conditions, degrade the mechanical behaviors and further decrease the carrying capacity of granite. The gradual degradation of the mechanical characteristics of granite after thermal treatment is mainly associated with the evolution of thermal micro-cracks based on optical microscopy observations. The unloading stress state induces the extension of tension cracks parallel to the axial direction, and thus, the mechanical properties are degraded. Temperatures above 400 degrees C have a more significant influence on the mechanical characteristics of granite than the unloading treatment, whereby 400 degrees C can be treated as a threshold temperature for the delineation of significant deterioration. This study is expected to support feasibility and risk assessments by means of providing data for analytical calculations and numerical simulations on granite exposed to high temperatures during geothermal energy extraction.…
Author details: | Zhennan Zhu, Hong Tian, Thomas KempkaORCiDGND, Guosheng Jiang, Bin Dou, Gang MeiORCiD |
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DOI: | https://doi.org/10.1007/s11053-021-09815-7 |
ISSN: | 1520-7439 |
ISSN: | 1573-8981 |
Title of parent work (English): | Natural resources research / sponsored by the International Association for Mathematical Geology |
Publisher: | Springer Science + Business Media B.V. |
Place of publishing: | New York, NY [u.a.] |
Publication type: | Article |
Language: | English |
Date of first publication: | 2021/01/30 |
Publication year: | 2021 |
Release date: | 2024/05/22 |
Tag: | Granite; Mechanical properties; Micro-structure; Thermal treatment; Unloading |
Volume: | 30 |
Issue: | 3 |
Number of pages: | 20 |
First page: | 2733 |
Last Page: | 2752 |
Funding institution: | National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [41602374, 41674180]; Fundamental Research Funds for the Central Universities-Cradle Plan [CUGL170207]; National Key Research and Development Program of China [2019YFB1504201, 2019YFB1504203, 2019YFB1504204] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
DDC classification: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer review: | Referiert |