Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings

Abstract The triaxial direct shear behavior of granite under high-temperature and stress-coupled conditions is critical for the safety evaluation of underground openings exposed to elevated temperatures, such as those in high-level radioactive waste disposal facilities. This study investigates the i...

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Main Authors: Binhui Liu, Zaobao Liu, Jianyu Xu, Liang Chen, Feng Tian, Biao Wang, Qiang Yang, Hongsu Ma
Format: Article
Language:English
Published: Springer 2025-04-01
Series:Geomechanics and Geophysics for Geo-Energy and Geo-Resources
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Online Access:https://doi.org/10.1007/s40948-025-00961-3
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author Binhui Liu
Zaobao Liu
Jianyu Xu
Liang Chen
Feng Tian
Biao Wang
Qiang Yang
Hongsu Ma
author_facet Binhui Liu
Zaobao Liu
Jianyu Xu
Liang Chen
Feng Tian
Biao Wang
Qiang Yang
Hongsu Ma
author_sort Binhui Liu
collection DOAJ
description Abstract The triaxial direct shear behavior of granite under high-temperature and stress-coupled conditions is critical for the safety evaluation of underground openings exposed to elevated temperatures, such as those in high-level radioactive waste disposal facilities. This study investigates the influence of thermal–mechanical coupling methods on the triaxial direct shear behavior of granite sourced from the Beishan Underground Research Laboratory in China by a self-developed triaxial direct shearing device. Two distinct thermal–mechanical loading paths were tested: (1) stress applied after temperature increase (SAT) and stress applied before temperature increase (SBT), with the latter simulating in situ host rock conditions. The results reveal that the peak direct shear strength of Beishan granite at a normal stress of 15 MPa decreased monotonically by approximately 5.45% as the temperature increased from room temperature to 150 °C under the SBT loading path. In contrast, under the SAT loading path, the peak strength initially increased by 28.5% from room temperature to 90 °C, followed by a subsequent decrease of 26.6% from 90 to 150 °C. These differences are attributed to the dual effects of thermal expansion in granite minerals, which are influenced by the temperature-stress coupling path. An integrated evaluation index M was developed to assess the granite strength evolution under high temperatures. When the evaluation index M > 5, the granite exhibits thermal strengthening; conversely, when M ≤ 5, the strength decreases in real-time high-temperature tests. These findings provide valuable insights for the stability assessment of engineering projects subjected to high stress and temperature conditions.
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spelling doaj-art-d964abbca87845f69453363f0d5d29c02025-08-20T03:53:32ZengSpringerGeomechanics and Geophysics for Geo-Energy and Geo-Resources2363-84192363-84272025-04-0111112210.1007/s40948-025-00961-3Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openingsBinhui Liu0Zaobao Liu1Jianyu Xu2Liang Chen3Feng Tian4Biao Wang5Qiang Yang6Hongsu Ma7State Key Laboratory of Intelligent Deep Metal Mining and Equipment, Northeastern UniversityState Key Laboratory of Intelligent Deep Metal Mining and Equipment, Northeastern UniversityState Key Laboratory of Intelligent Deep Metal Mining and Equipment, Northeastern UniversityCAEA Innovation Center for Geological Disposal of High-Level Radioactive Waste, Beijing Research Institute of Uranium GeologyState Key Laboratory of Intelligent Deep Metal Mining and Equipment, Northeastern UniversityState Key Laboratory of Intelligent Deep Metal Mining and Equipment, Northeastern UniversityState Key Laboratory of Intelligent Deep Metal Mining and Equipment, Northeastern UniversityCAEA Innovation Center for Geological Disposal of High-Level Radioactive Waste, Beijing Research Institute of Uranium GeologyAbstract The triaxial direct shear behavior of granite under high-temperature and stress-coupled conditions is critical for the safety evaluation of underground openings exposed to elevated temperatures, such as those in high-level radioactive waste disposal facilities. This study investigates the influence of thermal–mechanical coupling methods on the triaxial direct shear behavior of granite sourced from the Beishan Underground Research Laboratory in China by a self-developed triaxial direct shearing device. Two distinct thermal–mechanical loading paths were tested: (1) stress applied after temperature increase (SAT) and stress applied before temperature increase (SBT), with the latter simulating in situ host rock conditions. The results reveal that the peak direct shear strength of Beishan granite at a normal stress of 15 MPa decreased monotonically by approximately 5.45% as the temperature increased from room temperature to 150 °C under the SBT loading path. In contrast, under the SAT loading path, the peak strength initially increased by 28.5% from room temperature to 90 °C, followed by a subsequent decrease of 26.6% from 90 to 150 °C. These differences are attributed to the dual effects of thermal expansion in granite minerals, which are influenced by the temperature-stress coupling path. An integrated evaluation index M was developed to assess the granite strength evolution under high temperatures. When the evaluation index M > 5, the granite exhibits thermal strengthening; conversely, when M ≤ 5, the strength decreases in real-time high-temperature tests. These findings provide valuable insights for the stability assessment of engineering projects subjected to high stress and temperature conditions.https://doi.org/10.1007/s40948-025-00961-3GraniteTriaxial direct shearHigh temperature and high-stress couplingShear strengthDeep rock engineering
spellingShingle Binhui Liu
Zaobao Liu
Jianyu Xu
Liang Chen
Feng Tian
Biao Wang
Qiang Yang
Hongsu Ma
Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings
Geomechanics and Geophysics for Geo-Energy and Geo-Resources
Granite
Triaxial direct shear
High temperature and high-stress coupling
Shear strength
Deep rock engineering
title Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings
title_full Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings
title_fullStr Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings
title_full_unstemmed Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings
title_short Triaxial direct shear behavior and strength evaluation of granite under two high-temperature and stress-coupled conditions in deep underground openings
title_sort triaxial direct shear behavior and strength evaluation of granite under two high temperature and stress coupled conditions in deep underground openings
topic Granite
Triaxial direct shear
High temperature and high-stress coupling
Shear strength
Deep rock engineering
url https://doi.org/10.1007/s40948-025-00961-3
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