Study of fracture toughness and weakening mechanisms in gypsum interlayers in corrosive environments

Meng, Tao; Hu, Yue; Fang, Ruiling; Kok, J.S.M.; Fu, Qingnan; Gui, Feng

doi:10.1016/j.jngse.2015.06.027

Cited by 25 publications

(11 citation statements)

References 28 publications

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“…Based on the study of Meng et al . [ 24 , 39 ], the water inside the gypsum may be bound or absorbed water, which not only increases its porosity but also causes all grains boundaries to open. Besides, the calcium sulphate dihydrate (CaSO 4 ·2H 2 O) crystal belongs to the monoclinic crystal series.…”

Section: The Results and Discussionmentioning

confidence: 99%

“…This is because water can easily penetrate into the interior of the gypsum via capillary action due to the hydrophilic nature of gypsum. Based on the study of Meng et al [24,39], the water inside the gypsum may be bound or absorbed water, which not only increases its porosity but also causes all bound via hydrogen bonds, the bonds can be easily broken by forces such as heat or water. This bond breakage can dislocate the layer structure and separate the chains of molecules, eventually increasing the porosity and decreasing the strength of the material.…”

Section: Effect Of Water-chloride Ion-temperaturementioning

confidence: 99%

“…microstructure, macrostructure) of rock. The resulting changes in microstructure, such as pores and fissures, will lead to changes in the macroscopic properties of the rock, including significant changes in fracture toughness and fracture trajectories [24][25][26][27]. However, none of the studies mentioned above address the fracture toughness and fracture trajectories of gypsum interlayers in corrosive environment (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Study of mixed mode fracture toughness and fracture trajectories in gypsum interlayers in corrosive environment

2018

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Based on the engineering background of water dissolving mining for hydrocarbon storage in multi-laminated salt stratum, the mixed mode fracture toughness and fracture trajectory of gypsum interlayers soaked in half-saturated brine at various temperatures (20°C, 50°C and 80°C) were studied by using CSNBD (centrally straight-notched Brazilian disc) specimens with required inclination angles (0°, 7°, 15°, 22°, 30°, 45°, 60°, 75°, 90°) and SEM (scanning electron microscopy). The results showed: (i) The fracture load of gypsum specimens first decreased then increased with increasing inclination angle, due to the effect of friction coefficient. When soaked in brine, the fracture toughness of gypsum specimens gradually decreased with increasing brine temperature. (ii) When soaked in brine, the crystal boundaries of gypsum separated and became clearer, and the boundaries became more open between the crystals with increasing brine temperature. Besides, tensile micro-cracks appeared on the gypsum crystals when soaked in 50°C brine, and the intensity of tensile cracks became more severe when soaking in 80°C brine. (iii) The experimental fracture envelopes derived from the conventional fracture criteria and lay outside these conventional criteria. The experimental fracture envelopes were dependent on the brine temperature and gradually expanded outward as brine temperature increases. (iv) The size of FPZ (fracture process zone) was greatly dependent on the damage degree of materials and gradually increased with increase of brine temperature. The study has important implication for the control of shape and size of salt cavern.

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Section: The Results and Discussionmentioning

confidence: 99%

Section: Effect Of Water-chloride Ion-temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study of mixed mode fracture toughness and fracture trajectories in gypsum interlayers in corrosive environment

2018

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“…Toughness. In fracture mechanics, there are three types of fracture: mode I (tensile fracture), mode II (shear fracture), and mode III (out-of-plane tearing fracture) [20][21][22][23][24][25][26][27][28][29]. Among them, mode I fracture is the most frequently encountered in underground geotechnical engineering [20,30,31].…”

Section: Scb Specimens and Calculation Of Mode I Fracturementioning

confidence: 99%

Mode I Fracture Toughness Test and Fractal Character of Fracture Trajectory of Red Sandstone under Real-Time High Temperature

Zhang

2019

Advances in Materials Science and Engineering

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To evaluate the stability and compactness of high-temperature underground construction, it is necessary to test the fracture toughness of surrounding rock (red sandstone) under real-time high temperature. In this paper, SCB specimens recommended by the International Society for Rock Mechanics are used to measure the mode I fracture toughness of red sandstone at real-time high temperatures. Also, to reveal its fracture characteristics and fracture mechanism, the fracture morphology observation (SEM experiment), XRD experiment, mercury intrusion porosimetry testing, and fractal measurement of fracture trajectory are carried out on the red sandstone specimens at various temperatures. The results show that (1) temperature may have a significant impact on the fracture toughness and fracture characteristics of red sandstone. On the whole, the fracture toughness values decrease with the increase in temperature, while the fractal dimensions of fractal trajectories increase with the increase in temperature. (2) Temperature has a significant influence on the fracture mode of red sandstone. At relatively low temperatures (20°C–400°C), the main fracture mode is transgranular failure. At relatively high temperatures (400°C–700°C), the fracture mode is mainly intergranular failure. (3) The weakening mechanism of red sandstone is mainly due to the effect of thermal dehydration when the temperature is between 100°C and 400°C. When the temperature is between 400°C and 700°C, the weakening mechanism is mainly due to thermal cracking and the α-β phase transition of quartz.

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“…Thermal-hydrological-chemical (THC) interactions are widely recognized and studied by researchers from different fields, including hydraulic engineering, civil engineering and geological environmental engineering [1][2][3][4][5]. The existing research on THC coupling has benefited these different engineering disciplines, with each of them having different key interacting factors influencing various projects.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Microstructural Evolution of Glauberite and Its Weakening Mechanism under the Effect of Thermal-Hydrological-Chemical Coupling

et al. 2018

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The microstructures of rock gradually evolve with changes in the external environment. This study focused on the microstructure evolution of glauberite and its weakening mechanism under different leaching conditions. The porosity were used as a characteristic index to study the effect of brine temperature and concentration on crack initiation and propagation in glauberite. The research subjects were specimens of ϕ3 × 10 mm cylindrical glauberite core, obtained from a bedded salt deposit buried more than 1000 m underground in the Yunying salt formation, China. The results showed that when the specimens were immersed in solution at low temperature, due to hydration impurities, cracks appeared spontaneously at the centre of the disc and the solution then penetrated the specimens via these cracks and dissolved the minerals around the crack lines. However, with an increase of temperature, the dissolution rate increased greatly, and crack nucleation and dissolved regions appeared simultaneously. When the specimens were immersed in a sodium chloride solution at the same concentration, the porosity s presented gradual upward trends with a rise in temperature, whereas, when the specimens were immersed in the sodium chloride solution at the same temperature, the porosity tended to decrease with the increase of sodium chloride concentration. In the process of leaching, the hydration of illite, montmorillonite, and the residual skeleton of glauberite led to the expansion of the specimen volume, thereby producing the cracks. The diameter expansion rate and the expansion velocity of the specimen increased with temperature increase, whereas, due to the common-ion effect, the porosity of the specimen decreases with the increase of sodium chloride solution concentration.

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Study of fracture toughness and weakening mechanisms in gypsum interlayers in corrosive environments

Cited by 25 publications

References 28 publications

Study of mixed mode fracture toughness and fracture trajectories in gypsum interlayers in corrosive environment

Study of mixed mode fracture toughness and fracture trajectories in gypsum interlayers in corrosive environment

Mode I Fracture Toughness Test and Fractal Character of Fracture Trajectory of Red Sandstone under Real-Time High Temperature

Experimental Study of the Microstructural Evolution of Glauberite and Its Weakening Mechanism under the Effect of Thermal-Hydrological-Chemical Coupling

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