Mechanical and Heterogeneous Properties of Coal and Rock Quantified and Mapped at the Microscale

Sun, Changlun; Li, Guichen; Zhang, Suhui; Xu, Jiahui; Yang, Haibo

doi:10.3390/app10010342

Cited by 14 publications

(4 citation statements)

References 55 publications

(66 reference statements)

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“…Taking shale, mudstone, and coal, derived from China's coal mines as examples [37], three nanoindentation tests labeled sample-1, -2, and -3 following the protocol in Figure 1(b) were made on the random locations on each sample. e hardness and elastic modulus of three nanoindentation tests on each sample was computed by using the Oliver-Pharr method through stage o-a in Figure 1(b) [34].…”

Section: Resultsmentioning

confidence: 99%

Explanation on the Abnormal Behavior during the Nanoindentation Holding Stages by Amplifying Oscillation

et al. 2022

Advances in Civil Engineering

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Recently, the holding states of nanoindentation experiments have been widely used to analyze the time-dependent deformations of various rocks, and the dynamic mechanical analysis (DMA) method seems to be more applicable than the quasi-static mechanical analysis (QMA) method when the influence of creep deformation on mechanical properties of rocks was analyzed. However, the former method causes an abnormal behavior during the creep holding stages that was not clearly interpreted.2 Consequently, in this study, by amplifying the oscillation of the DMA method, the mechanical mechanism of this phenomenon was explained. Experimental results confirm that the rheological deformation of rocks consists of the creep deformation (depth increasing) and the elastic aftereffect deformation (depth decreasing) during the creep time with small oscillation; once the elastic aftereffect deformation exceeds the creep deformation, the abnormal behavior can be observed. Besides, some other abnormal behaviors might be found for other rock materials when the DMA method with different oscillations is used, which illustrates the complexity and limitation of applying this method. Thus, the QMA method was recommended to investigate the above questions in future studies.

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Section: Resultsmentioning

confidence: 99%

Explanation on the Abnormal Behavior during the Nanoindentation Holding Stages by Amplifying Oscillation

et al. 2022

Advances in Civil Engineering

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“…The hydrological properties of the materials are mainly swelling and disintegration after encountering water. The repeated changes of the wet and dry cycle will destroy the mudstone [31]. Therefore, Region P1 had serious surface deformation.…”

Section: The Holocene Aeolianmentioning

confidence: 99%

Characteristics of Surface Deformation in Lanzhou with Sentinel-1A TOPS

Wang

Yan

et al. 2020

Geosciences

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While surface deformations and their impact on buildings have been observed in the city of Lanzhou, it is difficult to find studies of surface deformation and the influential factors in the recent decades. This study was designed to detect the spatial position of these surface deformations and to understand the mechanism behind them. Sentinel-1A TOPS model image data acquired in descending orbits between March 2015 and May 2019 were processed by using Small Baseline Subsets Interferometry (SBAS)-Interferometric Synthetic Aperture Radar (InSAR) technology, and then compared with geology, tectonical aspects of the study area and land cover types in Lanzhou. The results reveal that the land surface deformation is uneven in this city, and seven surface deformation regions were detected in the following areas: the north freight yard, Jiuzhou, Country garden, Donggang, Yanjiaping, Zhongxinping and Liuquan town. The land surface deformation rate in Lanzhou ranges from −82.13 mm/year to 19.31 mm/year. Time-series land surface deformation analysis showed that deformation increased over time in major deformation regions. Surface deformation expansion was significant after June 2017and it continued to expand. The surface deformation of Lanzhou is affected by natural factors (geology and geological faults) and human activities (land cover types/land cover changes). Local geological conditions control the location of the surface deformation process. These findings provide compelling data and theoretical support for disaster prevention and reduction in Lanzhou.

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“…The experimental surface fixed with epoxy resin was then polished and exposed. The polishing protocol detailed in (C. Sun, Li, Zhang, et al, 2020) was followed. This protocol includes a coarse polishing on 3000 grit emery papers and a fine polishing using oil-based diamond suspension with abrasive grain sizes ranging between 3 and 0.5 μm.…”

Section: The Targeting Nanoindentation Techniquementioning

confidence: 99%

“…Zhang Fan et al obtained the hardness and elastic modulus of compositions in granite (Fan et al, 2017). Taking Chinese sub-bituminous coal as an example, the relationship between its morphologies and its nano-mechanical properties was investigated (Y. ; Meng et al and Sun et al calculated the mean values of the nanoindentation mechanical parameters to represent that of standard coal samples (Meng et al, 2020;C. Sun, Li, Zhang, et al, 2020) and discussed the influence of quartz and kaolinite on the mechanical properties of coal matrix(C. Sun, Li, Gomah, et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on the nanoindentation viscoelastic constitutive model of quartz and kaolinite in mudstone

Sun

Li²,

Elgharib

et al. 2020

Preprint

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The creep behaviors in deep underground engineering structures, especially in soft rocks, have a remarkable impact on the long-term stability of the excavations, which finally leads to the high risk and failure of it. Accordingly, it is essential to recognize the time-dependent deformation through the investigation of this phenomenon. In this study, the creep behaviors of soft rocks have been widely examined to help understand the underlying mechanism of the extended time-dependent deformation. Due to the limited results about the time-dependent properties of the constituents of the rock that reveal their heterogeneity, the targeting nanoindentation technique (TNIT), was adopted to investigate the viscoelastic characteristics of kaolinite and quartz in a two-constituent mudstone sample. The TNIT consists of identifications of mineralogical ingredients in mudstone with nanoindentation experiments on each identified constituent. After conducting experiments, the unloading stages of the typical indentation curves were analyzed to calculate the hardness and elastic modulus of both elements in mudstone. Additionally, the 180 s load-holding stages with the peak load of 50 mN were transformed into the typical creep strain-time curves for fitting analysis by using the Kelvin model, the standard viscoelastic model, and the extended viscoelastic model. Fitting results show that the standard viscoelastic model not only can perfectly express the nanoindentation creep behaviors of both kaolinite and quartz but also can produce suitable constants used to measure their creep parameters. Furthermore, the creep parameters of kaolinite are much smaller than that of quartz, which causes the considerable time-dependent deformation of the soft mudstone. Eventually, the standard viscoelastic model was also verified on the quartz in a sandstone sample.

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Mechanical and Heterogeneous Properties of Coal and Rock Quantified and Mapped at the Microscale

Cited by 14 publications

References 55 publications

Explanation on the Abnormal Behavior during the Nanoindentation Holding Stages by Amplifying Oscillation

Explanation on the Abnormal Behavior during the Nanoindentation Holding Stages by Amplifying Oscillation

Characteristics of Surface Deformation in Lanzhou with Sentinel-1A TOPS

Experimental investigation on the nanoindentation viscoelastic constitutive model of quartz and kaolinite in mudstone

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