Micro and macro evaluation of tensile characteristics of anisotropic rock mass after high temperatures treatment-a case study of Lingshi Gneiss

Kou, Baofu; Zhang, Dengke; Meng, Tao; Li, Zhenshun; Wang, Yongshuai; Liu, Guanchen; Hao, Ruijie; Chen, Tianqi; Zhang, Zhijiang

doi:10.1016/j.geothermics.2022.102409

Cited by 17 publications

(4 citation statements)

References 54 publications

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“…Some researchers discovered that the uniaxial compressive strength of rock samples exhibits a certain threshold, initially increasing and then decreasing with rising temperatures [23][24][25] . The tensile strength and fracture toughness of rocks show a pattern of first increasing and then decreasing as temperatures rise 26,27 . With gradually increasing thermal treatment temperatures, the fracture characteristic of granite exhibits a shift from brittle to ductile 28,29 .…”

Section: Introductionmentioning

confidence: 99%

Influence of coupled water and thermal treatments on the fracture characteristics of a typical sandstone

Luo,

Zhong,

Ren

et al. 2024

Preprint

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Understanding the fracture behavior of rock after coupled water and thermal environment is important for many geotechnical projects. The influence of coupled water and thermal treatments on the mode-I and mode-II fracture toughness and characteristics of sandstone was investigated using notched deep beam specimens. The experimental results indicate a significant reduction in both mode-I and mode-II fracture toughness of sandstone under varying soaking temperatures. As the water temperatures increase, a slightly rising trend is observed in both mode-I and mode-II fracture toughness within the studied soaking temperature range. At lower soaking temperatures, sandstone exhibits typical brittle characteristics, which gradually transition to ductile properties as the temperature increases. Based on the Maximum Tangential Stress (MTS) criterion, the predicted values of mode-II fracture toughness and the fracture process zone were discussed. The results show that both the GMTS and MTS criteria exhibit inaccuracies in predicting the Mode-II fracture toughness of sandstone treated at different soaking temperatures. However, the GMTS criterion, which incorporates T-stress, demonstrates smaller errors compared to the MTS criterion. The study shows that the radius r0 of the fracture process zone is not a constant under both mode-I and mode-II loading conditions. The calculation of the fracture process zone radius r0 in the MTS criterion requires further theoretical and experimental study.

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Section: Introductionmentioning

confidence: 99%

Influence of coupled water and thermal treatments on the fracture characteristics of a typical sandstone

Luo,

Zhong,

Ren

et al. 2024

Preprint

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“…Influenced by factors such as geological tectonics, engineering depth, fire accidents, magma and underground hot water activities (Huang et al, 2021; Wang et al, 2022; Hao et al, 2022) [8][9][10] , high temperature phenomenon of rocks is finding in many fields such as mining, energy, geology and civil engineering (Etzelmüller et al, 2022; Hu et al, 2022) [11][12] . For example, deep resource exploitation(Zhao et al, 2022) [13] , nuclear waste disposal (Xu et al, 2022) [14] , underground storage and exploitation of oil and natural gas (Shi & Xu, 2013; Jun et al, 2016) [15][16] , exploitation and utilization of geothermal resources (Kou et al, 2022; Gao et al, 2022; Wang et al, 2023) [17][18][19] , safe drainage and comprehensive utilization of coal seam gas (T.D. et al, 2018) [20] , deep underground engineering, etc., all involve the mechanical properties of rocks in high temperature environment (Hao et al, 2022; Liu et al, 2022) [10,21] .…”

mentioning

confidence: 99%

“…In the past decades, many valuable results have been achieved about temperature on rock failure and mechanics. A large number of scholars have carried out comprehensive and systematic work on physical and mechanical parameters, deformation and fracture characteristics (macro-fracture, micro-fracture and threshold temperature) of rock mass under high temperature in combination with rock mechanics tests, acoustic emission, scanning electron microscope (SEM), photometric microscope and computed tomography (CT) technology (Jansen et al, 1993;Hajpál, 2002;Tian et al, 2012;Plevová et al, 2010) [22][23][24] , and carried out corresponding theoretical work, such as fracture mechanism (Kou et al, 2022) [17] , failure criterion (Zhou et al, 2022) [3] and constitutive model (Ogata et al, 2022; Wang et al, 2022) [5,9] . For example, through Brazilian tests of gabbro and marble at 100~600℃, Zhang et al (1994) [25] found that the fracture toughness and tensile strength of rocks decreased with the increase of temperature.…”

mentioning

confidence: 99%

“…Hao et al (2022) [10] found that the higher the temperatures, the more complex the pores, and the larger the fractal dimensions (mesopores and macropores) for granite. For Gneiss, heated from 25-700 ℃, the evolution of tensile strength has experienced three stages: at low temperature stage (25-200 ℃), the tensile strength increases slowly with the increase of temperature; at medium-temperature stage (200-400 •C), the tensile strength decreases slowly with the increase of temperature; at high temperature stage (400-700 ℃), the tensile strength decreases rapidly with the increase of temperature (Kou et al 2022) [17] . Ahmed et al (2022) [28] investigated rhyolitic turf rock's physical and mechanical properties at 200, 400, 600, and 800 ℃), and pointed out that the mechanical properties (uniaxial compressive strength (UCS) and Young's modulus) decrease drastically beyond 500-600 ℃.…”

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confidence: 99%

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Fracture mechanism and constitutive model considering post-peak plastic deformation of marble under thermal-mechanical action

Gao,

Li,

Zhang

et al. 2024

Preprint

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Temperature plays an important impact on rock mechanical properties. In this paper, the mechanical properties, fracture mechanism and constitutive model of marble under thermal-mechanical action are studied by experimental and theoretical methods. The results show that the deformation of marble under the condition of 20-120 ℃ and 15 MPa can be divided into four progressive failure stages: compaction, linear elasticity, crack propagation and post-peak failure. The stress-strain curve is not obviously affected by temperature, characterized by strain softening and plastic deformation. The macroscopic fracture characteristics change from shear failure to tensile mixed failure with the increase of temperature. With the increase of temperature, the strength of marble tends to decrease, indicating that temperature increase has a weakening effect on marble, and there are temperature-sensitive areas of 20-60℃ and temperature sub-sensitive areas of 60-120℃. The elastic modulus of marble decreases and Poisson's ratio increases with increasing temperature. The energy evolution law of marble under different temperature is basically the same, which shows that before crack initiation, the energy dissipation is less, and after the damage and yielding occurs, the energy dissipation increases quickly. The energy dissipation in the failure process is mainly used for crack initiation-connection-penetration, as well as plastic deformation caused by friction and slip of cracks, and the plastic deformation and energy dissipation have good linear characteristics. The statistical damage constitutive model based on three-parameter Weibull distribution function can effectively reflect the characteristics of post-peak plastic deformation and strain softening. The weakening effect of marble at 20-120℃ is related to its internal moisture excitation. With the increase of temperature, water is stimulated to absorb and attach to the original relatively dry interface, which plays a role in lubrication. The relative motion friction resistance between solid particles or crack surfaces decreases, which leads to crack initiation and friction energy consumption reduction, changes the specific surface energy of rocks and weakens the strength of marble. The results provide a theoretical basis for predicting and evaluating the long-term stability and safety of surrounding rock of underground deep engineering in complex environment with high ground temperature and high geo-stress.

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Experimental study on the physical and mechanical properties of carbonatite rocks under high confining pressure after thermal treatment

Yang,

Wang,

Yao

et al. 2024

Deep Underground Science and Engineering

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Oil and gas exploration studies have been increasingly moving deeper into the earth. The rocks in deep and ultra‐deep reservoirs are exposed to a complex environment of high temperatures and large geo‐stresses. The Tarim oilfield in the Xinjiang Uygur Autonomous Region (Xinjiang for short), China, has achieved a breakthrough in the exploration of deep hydrocarbon reservoirs at a depth of over 9000 m. The mechanical properties of deep rocks are significantly different from those of shallow rocks. In this study, triaxial compression tests were conducted on heat‐treated carbonatite rocks to explore the evolution of the mechanical properties of carbonatite rocks under high confining pressure after thermal treatment. The rocks for the tests were collected from reservoirs in the Tarim oilfield, Xinjiang, China. The experiments were performed at confining pressures ranging from atmospheric to 120 MPa and temperatures ranging from 25 to 500°C. The results show that the critical confining pressure of the brittle–ductile transition increases with increasing temperature. Young's modulus is negatively correlated with the temperature and positively correlated with the confining pressure. As the confining pressure increases, the failure mode of the specimens gradually transforms from shear fracture failure into “V”‐type failure and finally into bulging failure (multiple shear fractures). With increasing temperature, the failure angle tends to decrease. In addition, an improved version of the Mohr‒Coulomb strength criterion with a temperature‐dependent power function was proposed to describe the failure strength of carbonatite rocks after exposure to high temperature and high confining pressure. The surface of the strength envelope of this criterion is temperature dependent, which could reflect the strength evolution of rock under high confining pressures after thermal treatment. Compared with other strength criteria, this criterion is more capable of replicating physical processes.

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Micro and macro evaluation of tensile characteristics of anisotropic rock mass after high temperatures treatment-a case study of Lingshi Gneiss

Cited by 17 publications

References 54 publications

Influence of coupled water and thermal treatments on the fracture characteristics of a typical sandstone

Influence of coupled water and thermal treatments on the fracture characteristics of a typical sandstone

Fracture mechanism and constitutive model considering post-peak plastic deformation of marble under thermal-mechanical action

Experimental study on the physical and mechanical properties of carbonatite rocks under high confining pressure after thermal treatment

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