Study on Microstructural Evolution of Marble Under Cyclic Dynamic Impact Based on NMR

Jiang, Zhen; Deng, Hongwei; Liu, Taoying; Tian, Guanglin; Tang, Leihu

doi:10.1109/access.2019.2935841

Cited by 16 publications

(8 citation statements)

References 57 publications

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“…Zhang [9] and Deng [10] discussed the micro-pore structure evolution of sandstone under freeze-thaw cycles by NMR analysis. Liu [11] and Jiang [12] carried out the cyclic freeze-thaw test and cyclic dynamic impact test on granite and sandstone, studying the microporosity changes of different rocks under cyclic impact by NMR. Li [13][14][15][16] carried out laboratory freeze-thaw cycle tests on sandstone materials at different cycle numbers and studied the pore structure evolution and fractal characteristics of pores with different radius under freeze-thaw cycles were studied by NMR and imaging analysis.…”

Section: Introductionmentioning

confidence: 99%

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Deng

Tian

et al. 2020

Applied Sciences

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Micro-pore structure has a decisive effect on the physical and mechanical properties of porous materials. To further improve the composition of rock-like materials, the internal relationship between microscopic characteristics (porosity, pore size distribution) and macroscopic mechanical properties of materials needs to be studied. This study selects portland cement, quartz sand, silica fume, and water-reducing agent as raw materials to simulate sandstone. Based on the Nuclear magnetic resonance (NMR) theory and fractal theory, the study explores the internal relationship between pore structure and mechanical properties of sandstone-like materials, building a compressive strength prediction model by adopting the proportion of macropores and the dimension of macropore pore size as dependent variables. Test results show that internal pores of the material are mainly macropores, and micropores account for the least. The aperture fractal dimension, the correlation coefficient of mesopores and macropores are quite different from those of micropores. Fractal characteristics of mesopores and macropores are obvious. The macropore pore volume ratio has a good linear correlation with fractal dimension and strength, and it has a higher correlation coefficient with pore volume ratio, pore fractal dimension and other variable factors. The compressive strength increases with the growth of pore size fractal dimension, but decreases with the growth of macropore pore volume ratio. The strength prediction model has a high correlation coefficient, credibility and prediction accuracy, and the predicted strength is basically close to the measured strength.

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Section: Introductionmentioning

confidence: 99%

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Deng

Tian

et al. 2020

Applied Sciences

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“…In the NMR test, the pore radius is proportional to the T2 value. Therefore, there is a T2 value that divides the pore fluid into bound fluid and free fluid, which is called the T2 cutoff value [31]. The T2 cutoff value divides the rock sample porosity into the bound fluid index (BVI) and free fluid index (FFI) by dividing the T2 spectrum distribution.…”

Section: T2 Spectralmentioning

confidence: 99%

“…Scholars have performed many experiments to determine the values of these model parameters. Based on previous studies, this paper assigns empirical values of 4, 2, and 10 to m, n, and C, respectively [31]. To directly reflect the characteristics of the pore connectivity with the freeze-thaw weathering cycles, the changes in porosity, IFP, MFP, T2 cutoff value, and permeability are plotted in Figures 8 and 9.…”

Section: T2 Spectralmentioning

confidence: 99%

“…Therefore, many researchers [25][26][27][28][29][30] have conducted much research through indoor experiments, numerical simulations, damage models, etc. Jiang [31] studied the response mechanism of two kinds of marble microstructures to the dynamic cyclic impact under the condition of freeze-thaw weathering cycles, and he found that under the cyclic dynamic impact, the two marble types exhibited the same trend: the porosity gradually decreased, the pore size continuously decreased, the pore structure tightened, and the permeability weakened. Weng [32] et al studied the response mechanism of the rock microstructure and dynamic mechanical behaviour to freeze-thaw weathering cycles.…”

Section: Introductionmentioning

confidence: 99%

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Research on the Pore Evolution of Sandstone in Cold Regions under Freeze-Thaw Weathering Cycles Based on NMR

et al. 2020

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The evolution of the rock pore structure is an important factor influencing rock mechanical properties in cold regions. To study the mesoscopic evolution law of the rock pore structure under freeze-thaw weathering cycles, a freeze-thaw weathering cycle experiment was performed on red sandstone from the cold region of western China with temperatures ranging from -20°C to +20°C. The porosity, T2 spectral distribution, and magnetic resonance imaging (MRI) characteristics of the red sandstone after 0, 20, 40, 60, 80, 100, and 120 freeze-thaw weathering cycles were measured by the nondestructive detection technique nuclear magnetic resonance (NMR). The results show that the porosity of sandstone decreases first and then increases with the increase of the freeze-thaw weathering cycles and reaches the minimum at 60 of freeze-thaw weathering cycles. The evolution characteristics of porosity can be divided into three stages, namely, the abrupt decrease in porosity, the slow decrease in porosity, and the steady increase in porosity. The evolution characteristics of the T2 spectrum distribution, movable fluid porosity (MFP), and MRI images in response to the freeze-thaw weathering process are positively correlated with the porosity. Analysis of the experimental data reveals that the decrease in the porosity of the red sandstone is mainly governed by mesopores, which is related to the water swelling phenomenon of montmorillonite. Hence, the pore connectivity decreases. As the number of freeze-thaw cycles increases, the effect of the hydrophysical reaction on the porosity gradually disappears, and the frost heaving effect caused by the water-ice phase transition gradually dominates the pore evolution law of red sandstone.

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“…elastic modulus and the shear modulus) under cyclic loading condition and found that rock specimens stiffen during loading and soften during unloading. Jiang et al [8] found that the porosity and pore size of marble rock gradually decrease under cyclic loading, which indicated that its framework becomes compacted. Apart from marble rock, red sandstone was also investigated by this research group, and the authors concluded that the damage variables showed a strong nonlinear relationship and increased with the loading cycles number [9].…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

et al. 2020

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Assisted ultrasonic vibration technology has received great interest in the past few years for petroleum and mining engineering related to hard rock breaking. Understanding the fatigue behaviour and damage characteristics of rock subject to ultra-high-frequency loading is vital for its application. In this research, we conducted ultrasonic vibration breaking rock experiments combined with an ultra-dynamic data receiver and strain gauges to monitor the development of strain in real time. The experimental results show that the strain curve is U-shaped, and it can be divided into three stages: the strain first decreases, then remains steady (with light fluctuations) and finally increases. The sample first underwent compressive deformation, and no rupture occurred. As the vibration continued, the compressive deformation decreased with the initiation and propagation of cracks, and fragmentation occurred. To elucidate the crack evolution mechanism of the granite specimens, numerical simulations were performed using particle flow code in two dimensions (PFC2D), and an improved fatigue damage model based on the flat-joint contact model was proposed. The numerical results indicate that this model can effectively reproduce the fatigue characteristics of hard brittle rocks under ultrasonic vibration. By analysing the stress and strain fields and cracking process, the crack evolution mechanism in the brittle hard rock under ultra-high-frequency loading is revealed. These experimental and numerical results are expected to improve the understanding of the fragmentation mechanism of rock under assisted ultrasonic vibration.

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Study on Microstructural Evolution of Marble Under Cyclic Dynamic Impact Based on NMR

Cited by 16 publications

References 57 publications

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Research on the Pore Evolution of Sandstone in Cold Regions under Freeze-Thaw Weathering Cycles Based on NMR

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

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