NMR Pore Structure and Dynamic Characteristics of Sandstone Caused by Ambient Freeze-Thaw Action

Ke, Bo; Zhou, Keping; Deng, Hongwei; Bin, Feng

doi:10.1155/2017/9728630

Cited by 28 publications

(21 citation statements)

References 40 publications

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“…The system consists of a specially shaped striker, an incident bar, a transmission bar, an absorption bar, and a damper. The incident bar, transmission bar, and absorption bar are all 40Cr steel with a longitudinal wave velocity of 5400 m/s, a density of 7810 kg/m 3 , and an elastic modulus of 240 GPa [30,38,46]. Two strain gauges are attached to the incident and transmission bars to record the deformation of the two bars.…”

Section: Ucs and Shpb Testsmentioning

confidence: 99%

“…In Figure 10, the transmitted wave (Tr) basically overlaps with the curve of the sum (In + Re) of the incident and reflected waves, indicating that the specimen is basically in the state of stress equilibrium before reaching the peak strength during dynamic loading and the test result is reliable. In addition, the inertial effects are ignored because there is no global force difference in the sandstone specimen to induce inertial forces [38,46].…”

Section: Mechanical Propertymentioning

confidence: 99%

“…Dynamic stress or impact loads, such as rockbursts, earthquakes, and blasting, have significant effects on the safety and stability of rock engineering, and many rock engineering disasters are caused by dynamic stresses or shocks. Under the action of dynamic loading, the dynamic mechanical behaviors of rocks, such as compressive strength, deformation, and failure process, are quite different from those of rocks under the static state [38][39][40][41][42][43]. Therefore, it is a very important issue to determine the rock dynamic properties accurately [44].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Chemical Corrosion on Pore Structure and Mechanical Properties of Sandstone

et al. 2019

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Chemical corrosion plays a significant role in affecting the properties of rock materials. To understand the effects of chemical corrosion on the pore structure and mechanical properties of sandstones, porosity, T2 spectrum distribution, and NMR images of sandstone specimens were measured after every 10 days of immersion in chemical solutions using the nuclear magnetic resonance (NMR) technique. Static uniaxial compressive tests and dynamic compressive tests were conducted using a conventional servo-controlled testing machine and a split Hopkinson pressure bar (SHPB) system for specimens treated with chemical corrosion. The test results showed that after being treated with chemical corrosion, the porosity of a specimen increased, the T2 spectrum distribution would successively shift towards the right, and the distribution of pores tended to become more irregular. Additionally, all of the compressive strength and elastic modulus of sandstone treated with chemical corrosion under static and dynamic loads decreased, and the peak strain increased. The effect order of a chemical solution on the pore structure and mechanical properties of sandstone was H2SO4>NaOH>distilled water, which would be related to the different mechanisms of a water-rock reaction. According to the experimental results, the correlations between the mechanical properties and porosity were established. The results can serve as a reference for research in related fields.

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Section: Ucs and Shpb Testsmentioning

confidence: 99%

Section: Mechanical Propertymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Chemical Corrosion on Pore Structure and Mechanical Properties of Sandstone

et al. 2019

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“…From the microscopic perspective, Zhou et al [21] investigated the effect of F-T cycles on the microscopic damage and dynamic mechanical properties of sandstone. e studies by Ke et al [22] show that the pore structure obviously changed with increasing F-T cycles and then an evolution equation for predicting the dynamic peak strength of sandstone after F-T cycles was put forwarded. Based on the above summary, it is clear that the number of F-T cycles was taken as a variable to study rock mechanical and fracture behavior in cold region engineering [23].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Dynamic Fracture Mechanism and Energy Evolution of Saturated Yellow Sandstone under Different Freeze‐Thaw Temperatures

Chen

Mao

Yang

et al. 2019

Advances in Civil Engineering

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The coupling effect of freeze-thaw (F-T) temperature and dynamic load on the dynamic mechanical properties and fracture mechanism of saturated yellow sandstone was experimentally investigated in this research. The dynamic compression tests on the specimen after different F-T temperatures (i.e., −5°С, −10°С, −15°С, −20°С, −30°С, and 20°С) have been carried out with split-Hopkinson pressure bar (SHPB) setup under eight F-T cycle numbers. The density and P-wave velocity of the specimens were obtained before and after the F-T tests. After the F-T tests, the specimen microstructures were examined via the scanning electron microscope (SEM). The dynamic fracture process was visualized by the high-speed camera. The particle size distribution and fragment shapes of the specimens were analyzed using a classifying screen. In addition, the energy dissipation law of specimens during the impact test was also discussed. Experimental results show that the dynamic elastic modulus, strength of the specimen, and the average particle size decrease with decreasing F-T temperature. SEM results reveal that low F-T temperature leads to severer internal damage of the specimen by inducing freeze-swell holes, interconnected cracks, and pore clusters. In addition, the fragmentation shapes of the failed specimens exhibit double-cone failure, single-side slope failure, double-side slope failure, and split failure. The energy dissipation increases gradually with increasing F-T temperature. This study helps to prevent geological disasters and optimize engineering design in cold regions.

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“…But the damage, which is defined by total power and dissipated energy, increases with the increase of cycle times. Ke et al [37,38] conducted NMR tests on rocks after freezethaw cycle (freeze-thaw temperature ranges from − 20°C to 20°C, with cycles of 0, 20, 60, 100, and 140 times, respectively) and did dynamic experiments on rocks under strain rate (75 s − 1 ) using the SHPB system. It is found that, with the increase of freeze-thaw cycle, the porosity of sandstone increases, the evolution of pore size tends to be uniform, the dynamic peak stress decreases, and the energy absorption increases.…”

Section: Introductionmentioning

confidence: 99%

Freeze‐Thaw Cycle Effect on Sputtering Rate of Water‐Saturated Yellow Sandstone under Impact Loading

Duan

Xian

et al. 2019

Advances in Civil Engineering

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In order to explore the impact of freeze-thaw temperature on the sputtering rate of water-saturated yellow sandstone under impact loading, in this paper, the Hopkinson pressure bar is used to conduct impact loading test on the water-saturated yellow sandstone at the same strain rate (74.22 s−1) under five different freeze-thaw temperatures. After impact loading, the yellow sandstone fragments are graded and screened by using the sizing screen, and the mass of fragments with different particle sizes after screening is counted. By transforming the fragments into spheres with the corresponding particle sizes, and combining the dissipated energy, the surface specific energy of yellow sandstone with different freeze-thaw temperatures is calculated. Finally, the sputtering rate of the fragments is obtained by using the relationship of total work, dissipated energy, and kinetic energy. The main conclusions are as follows: The freeze-thaw temperature has a significant effect on the fracture degree of yellow sandstone. The lower the freeze-thaw temperature is, the higher the fracture degree of yellow sandstone is, and the smaller the particle size distribution of fragments is. The fractal dimension of yellow sandstone increases with the decrease of freeze-thaw temperature, indicating that the damage of yellow sandstone is more serious. The dissipative energy of yellow sandstone increases with the decrease of freezing temperature, while the kinetic energy increases gradually when the freeze-thaw temperature is −30°C to −15°C and decreases gradually when the freeze-thaw temperature is −15°C to −5°C. The surface area and surface specific energy of yellow sandstone fragments both increase with the increase of freeze-thaw temperature. And the sputtering rate of yellow sandstone fragments increases gradually at freezing temperature from −30°C to −15°C and decreases gradually at −15°C to −5°C. Therefore, from the perspective of dynamic destruction process, the sputtering of yellow sandstone fragments at freezing temperatures of −15°C, −20°C, and −30°C is more intense than that at −5°C and −10°C. The results can provide some guidance for production in winter and winter regions.

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NMR Pore Structure and Dynamic Characteristics of Sandstone Caused by Ambient Freeze-Thaw Action

Cited by 28 publications

References 40 publications

Influence of Chemical Corrosion on Pore Structure and Mechanical Properties of Sandstone

Influence of Chemical Corrosion on Pore Structure and Mechanical Properties of Sandstone

Experimental Investigation on Dynamic Fracture Mechanism and Energy Evolution of Saturated Yellow Sandstone under Different Freeze‐Thaw Temperatures

Freeze‐Thaw Cycle Effect on Sputtering Rate of Water‐Saturated Yellow Sandstone under Impact Loading

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