Effect of heat-treatment on the dynamic compressive strength of Longyou sandstone

Huang, Sheng; Xia, Kaiwen

doi:10.1016/j.enggeo.2015.03.007

Cited by 82 publications

(17 citation statements)

References 36 publications

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“…Its application to engineering fields such as geomechanics is becoming popular as high-resolution industrial micro-computed tomography systems are more widely available. For example, CT imaging has been used to characterize the internal structure of geomaterials such as soil (Elyeznasni et al 2012;Garbout et al 2013;Hapca et al 2015;Otani et al 2001), rock (Huang et al 2013;Huang and Xia 2015;Ito et al 2001;Liu et al 2014b;Sugawara et al 2004;Vervoort et al 2004), concrete (Darma et al 2013;Fukuda et al 2014;Henry et al 2014), and asphalt (Liu et al 2014a;Masad and Kassem 2009;Taniguchi et al 2012;Tomoto and Moriyoshi 2009). In this paper, the Brazilian disc (BD) sample is adopted to measure the dynamic tensile strength of rock materials (Zhou et al 2012) under hydrostatic confinement.…”

Section: Introductionmentioning

confidence: 98%

An Experimental Study of Dynamic Tensile Failure of Rocks Subjected to Hydrostatic Confinement

Yao

Xia

2016

Rock Mech Rock Eng

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It is critical to understand the dynamic tensile failure of confined rocks in many rock engineering applications, such as underground blasting in mining projects. To simulate the in situ stress state of underground rocks, a modified split Hopkinson pressure bar system is utilized to load Brazilian disc (BD) samples hydrostatically, and then exert dynamic load to the sample by impacting the striker on the incident bar. The pulse shaper technique is used to generate a slowly rising stress wave to facilitate the dynamic force balance in the tests. Five groups of Laurentian granite BD samples (with static BD tensile strength of 12.8 MPa) under the hydrostatic confinement of 0, 5, 10, 15, and 20 MPa were tested with different loading rates. The result shows that the dynamic tensile strength increases with the hydrostatic confining pressure. It is also observed that under the same hydrostatic pressure, the dynamic tensile strength increases with the loading rate, revealing the so-called rate dependency for engineering materials. Furthermore, the increment of the tensile strength decreases with the hydrostatic confinement, which resembles the static tensile behavior of rock under confining pressure, as reported in the literature. The recovered samples are examined using X-ray micro-computed tomography method and the observed crack pattern is consistent with the experimental result. Keywords Dynamic tensile strength Á Hydrostatic confinement Á Brazilian disc Á SHPB Á Rate dependence Á X-ray CT Abbreviations SHPB Split Hopkinson pressure bar BD Brazilian disc CT Computed tomography LG Laurentian granite ISRM International Society for Rock Mechanics List of SymbolsA b Cross-sectional area of the bars (mm 2 ) A s Contact area between the sample and the transmitted bar (mm 2 ) r 0 Pump oil pressure (MPa) r 1 Stresses of the sample at the transmitted bar end (MPa) r 2 Stresses of the sample at the incident bar end (MPa) e i Incident strain wave e r Reflected strain wave e t Transmitted strain wave P 1 Force on incident end of the Brazilian disc specimen (N) P 2 Force on transmitted end of the Brazilian disc specimen (N) E b Young's modulus of the bars (GPa) B Thickness of the Brazilian disc specimen (mm) D Diameter of the Brazilian disc specimen (mm) r Tensile stress at the center of the Brazilian disc specimen (MPa) S Dynamic tensile strength of the Brazilian disc specimen (MPa) S 0 Static Brazilian tensile strength of Laurentian granite (MPa) & Kaiwen Xia

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Section: Introductionmentioning

confidence: 98%

An Experimental Study of Dynamic Tensile Failure of Rocks Subjected to Hydrostatic Confinement

Yao

Xia

2016

Rock Mech Rock Eng

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“…In order to obtain the crack initiation and propagation process in dynamic splitting tests, Zhou et al (2014) used a high-speed camera to monitor the fracturing processes in the Brazilian disc test. Scanning Electron Microscopy (SEM) and the X-ray Computer Tomography (CT) were also adopted to observe the microcracks of sandstone and mortar samples exposed to high temperature (Huang and Xia 2015;Yao et al 2016;Yao et al 2017). As a result of improvements in the shape of the sample, the ring sample (Li et al 2016), and the semidisc sample (Dai, Xia, and Luo 2008;Dai et al 2013;Xu et al 2016) were used to measure the tensile strength of the rock.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Energy Properties and Failure Modes of Heat-Treated Granite in Dynamic Splitting Test

Wang

Shi

Wang

et al. 2018

Geotechnical Testing Journal

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Dynamic Brazilian disc (or splitting) tests were carried out to study the characteristics of energy dissipation and failure behavior of heat-treated granite under impact loading. Six groups of granite samples were treated at the temperatures of 25°C, 100°C, 300°C, 500°C, 700°C, and 900°C, respectively. Each group of heat-treated samples was tested with three impact velocities of 5.4, 7.7 and 13.7 m/s in a modified split Hopkinson pressure bar. An average change rate of incident energy (ACRIE) was proposed to characterize the loading rate effect. The effects of treatment temperature and ACRIE on the energy dissipation and the failure patterns of samples under impact loading were investigated. The results show that the energy dissipation of the granite decreases with the increase of treatment temperature but increases with the increase of the ACRIE. A rise in treatment temperature or ACRIE may lead to smaller size and greater number of sample fragments. The effect of treatment temperature becomes more obvious as the ACRIE increases. The energy utilization ratio of the granite is generally less than 30 % and has an opposite effect when compared to the loading rate. In addition, the dynamic tensile strength of the samples increases almost linearly with the transmitted wave energy. These studies also indicate that the resistance of rock against tensile failure can be well characterized from the perspective of energy dissipation. Nomenclature c 0 = ultrasonic P-wave velocity of sample before heating c 1 = ultrasonic P-wave velocity of sample after heating D = thermal damage of sample V 0 = impact velocity of projectile W i = energy of incident stress wavė W i = average change rate of incident energyManuscript

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“…Meanwhile, brittle transcrystalline fracture morphology represented by cleavage fractures and transcrystalline cracks existed in the sandstone fracture at the lower hating rate (Figure 12(a)). At the heating rate of [20][21][22][23][24][25][26][27][28][29][30] ∘ C/min, there were two kinds of brittle fracture morphology (transcrystalline cracks and intergranular cracks) in the sandstone fracture after the impact tensile damage (Figure 12(b)). At the heating rates of 40-50 ∘ C/min, tearing ridges became the key fracture morphology, and transcrystalline cracks occurred locally and propagated gradually (Figure 12(c)).…”

Section: Evolutional Rules Of Morphology Features In Sandstonementioning

confidence: 99%

“…[17] tested the dynamic fracture toughness of Laurentian granite during thermal treatments and established that the granite fracture toughness decreased rapidly with rising temperatures; their more recent study reported that the tensile strength of granite was enhanced by thermal treatment temperatures up to 100 ∘ C [18]. However, the tensile strength decreased quickly and the dynamic mechanical properties of the granite weakened significantly when the temperature rose above 100 ∘ C. By conducting a dynamic Brazilian disk test with a SHPB system on Longyou sandstone after thermal treatments and analyzing the damage properties using CT scanning, scholars discovered a relationship between damage variables and loading strength; their studies concluded that the dynamic tensile strength of the rock increased as the loading rate and temperature decreased [19,20]. Further research results have shown that the dynamic tensile mechanical properties of rock are strongly dependent on temperature, and changes in mechanical properties are the result of varying temperatures that alter the rock's composition and microstructure [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

“…In order to provide valid theory support for the development of underground coal gasification and coal-bed methane mining, this paper conducted Brazilian disk tests on coal measure sandstone at 800 ∘ C temperature at different heating rates (5,10,20,30,40, and 50 ∘ C/min) and observed the subsequent slow cooling. Then, the material group and fine morphology of sandstone during heat treatments were measured by using X-ray diffraction and scanning electron microscopy (SEM), respectively.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Heating Rate on the Dynamic Tensile Mechanical Properties of Coal Sandstone during Thermal Treatment

Mao

et al. 2017

Shock and Vibration

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The effects of coal layered combustion and the heat injection rate on adjacent rock were examined in the process of underground coal gasification and coal-bed methane mining. Dynamic Brazilian disk tests were conducted on coal sandstone at 800 ∘ C and slow cooling from different heating rates by means of a Split Hopkinson Pressure Bar (SHPB) test system. It was discovered that thermal conditions had significant effects on the physical and mechanical properties of the sandstone including longitudinal wave velocity, density, and dynamic linear tensile strength; as the heating rates increased, the thermal expansion of the sandstone was enhanced and the damage degree increased. Compared with sandstone at ambient temperature, the fracture process of heat-treated sandstone was more complicated. After thermal treatment, the specimen had a large crack in the center and cracks on both sides caused by loading; the original cracks grew and mineral particle cracks, internal pore geometry, and other defects gradually appeared. With increasing heating rates, the microscopic fracture mode transformed from ductile fracture to subbrittle fracture. It was concluded that changes in the macroscopic mechanical properties of the sandstone were result from changes in the composition and microstructure.

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Effect of heat-treatment on the dynamic compressive strength of Longyou sandstone

Cited by 82 publications

References 36 publications

An Experimental Study of Dynamic Tensile Failure of Rocks Subjected to Hydrostatic Confinement

An Experimental Study of Dynamic Tensile Failure of Rocks Subjected to Hydrostatic Confinement

Analysis of Energy Properties and Failure Modes of Heat-Treated Granite in Dynamic Splitting Test

Effects of Heating Rate on the Dynamic Tensile Mechanical Properties of Coal Sandstone during Thermal Treatment

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