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Yanjun Shen
Geological Research Institute for Coal Green Mining, Xi'an University of Science and Technology, Xi'an, Shaanxi 710054, PR China

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Journal article
Published: 24 July 2021 in Cold Regions Science and Technology
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Comprehensive understanding the micro-debonding behavior and micro-mechanism at the interface transition zone (ITZ) of rock-concrete interfaces is essential for protecting shotcrete in tunnels. The ITZ is a weak area of the rock-concrete interface and is vulnerable to freeze-thaw (F-T) deterioration. Such deterioration can cause tunnel support failure. We used nanoindentation technology, stereo microscopy, and scanning electron microscopy (SEM) and considered several F-T actions to obtain four primary findings: (1) The elastic modulus and hardness values of the ITZ decrease continuously as the number of F-T cycles increases, and the trends of these changes are highly consistent. However, the decline of hardness value exceeds that of the elastic modulus as F-T cycling continues. (2) The thickness of the ITZ has a positive correlation with the number of F-T cycles. For example, the ITZ thickness increases from 60 μm (0 F-T cycles) to 80 μm (20 F-T cycles). (3) The volume fraction of micropores at the interface has a positive linear correlation with the number of F-T cycles; however, the volume fractions of low-density (LD) calcium-silicate-hydrate (C-S-H) gel, high-density (HD) C-S-H gel, and calcium hydrate (CH) at the interface exhibit negative correlations with the number of F-T cycles. These relationships indicate that micropores exert a degradation effect in response to F-T conditions. (4) The ITZ has high porosity and low sensitivity to debonding near the sandstone side. ITZ debonding is induced by F-T cycles because frost expansion and thaw contraction are significantly different in sandstone and cement paste. This study provides a reference for understanding the behavior and mechanism of debonding in rock-concrete interfaces subjected to F-T conditions.

ACS Style

Jia Pan; Yanjun Shen; Gengshe Yang; Huan Zhang; Hongwei Yang; Zihan Zhou. Debonding behaviors and micro-mechanism of the interface transition zone in sandstone-concrete interface in response to freeze-thaw conditions. Cold Regions Science and Technology 2021, 191, 103359 .

AMA Style

Jia Pan, Yanjun Shen, Gengshe Yang, Huan Zhang, Hongwei Yang, Zihan Zhou. Debonding behaviors and micro-mechanism of the interface transition zone in sandstone-concrete interface in response to freeze-thaw conditions. Cold Regions Science and Technology. 2021; 191 ():103359.

Chicago/Turabian Style

Jia Pan; Yanjun Shen; Gengshe Yang; Huan Zhang; Hongwei Yang; Zihan Zhou. 2021. "Debonding behaviors and micro-mechanism of the interface transition zone in sandstone-concrete interface in response to freeze-thaw conditions." Cold Regions Science and Technology 191, no. : 103359.

Journal article
Published: 12 May 2021 in Construction and Building Materials
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In cold regions, the highly supportive effect of concrete is particularly important to the safety of engineering construction. However, studies on the fracture debonding law and fracture criterion for rock–concrete binary composite interfaces under freeze–thaw (F-T) actions are relatively few. In this study, sandstone–concrete binary composite materials were considered as the research object. First, the debonding processes of the composites under F-T cycles were studied using nuclear magnetic resonance (NMR), stereoscopic microscope (SM) and scanning electron microscope (SEM) testing technology, and the distribution range of the interface influence zone (IIZ) was determined. In addition, the interface fracture criterion for sandstone-concrete composites under F-T actions was proposed, and the initiation law and influencing factors of interface cracks were discussed. The primary conclusions are as follows: (1) The IIZ, which has a thickness of approximately 12 mm, lies in the sandstone near the interface. Furthermore, the rock–concrete composite interface crack initiates and propagates mainly along the interface under F-T cycles, whereas it kinks into the IIZ at local positions. (2) Under F-T actions, the interface crack initiates along the material with the weaker mechanical properties or along the interface, and does not kink into the side of the material with the stronger mechanical properties. (3) The smaller the difference in mechanical properties between the materials on either side of the interface, the higher is the tendency for the interface crack to initiate and propagate along the interface. Moreover, the interface crack tends to kink into the material with the weaker mechanical property when there is a substantial difference in mechanical properties between the materials on either side. The study provides certain theoretical reference for further study of the debonding law of rock-concrete interface induced by F-T actions.

ACS Style

Zihan Zhou; Yanjun Shen; Huan Zhang; Yongzhi Wang; Hongwei Yang; Jia Pan; Xin Wei. Sandstone-concrete interface debonding mechanism under freeze-thaw actions: Fracture process and fracture criterion. Construction and Building Materials 2021, 294, 123526 .

AMA Style

Zihan Zhou, Yanjun Shen, Huan Zhang, Yongzhi Wang, Hongwei Yang, Jia Pan, Xin Wei. Sandstone-concrete interface debonding mechanism under freeze-thaw actions: Fracture process and fracture criterion. Construction and Building Materials. 2021; 294 ():123526.

Chicago/Turabian Style

Zihan Zhou; Yanjun Shen; Huan Zhang; Yongzhi Wang; Hongwei Yang; Jia Pan; Xin Wei. 2021. "Sandstone-concrete interface debonding mechanism under freeze-thaw actions: Fracture process and fracture criterion." Construction and Building Materials 294, no. : 123526.

Original paper
Published: 07 May 2021 in Bulletin of Engineering Geology and the Environment
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Achieving crack propagation and rapid deterioration of high-temperature rock masses by using cooling shocks is important for improving the efficiency of low-permeability oil and gas production, geothermal well pumping, and other engineering facilities. In this study, the temperatures of four groups of granite samples with holes were set as 150, 350, 550, and 750 °C. To study the crack propagation in high-temperature granite suffering from different cooling shocks, the cooling shock temperatures were set as −20, 0, 20, and 25 °C in experiments and an RFPA2D-Thermal numerical simulation. The results indicated that in the range of 350–550 °C, there is a critical temperature for the sudden change of the crack macroscopic shape. Numerous open cracks appeared on the rock surface, and the thermal damage caused by the cooling shocks was significantly enhanced within the temperature range. Additionally, under the action of the cooling shocks, cracks were initiated in the high-temperature granite at the boundary of the cooling shock hole and the sample and extended radially to the interior of the sample. Moreover, in the process of crack propagation, there was always an annular heat-balance zone inside the rock. Thus, the cracks generated at the boundary of the cube are not connected to the cracks formed at the center hole. A larger temperature gradient in the rock led to a higher crack propagation rate, larger penetration depth, and higher density of cooling-induced cracks. The results of this study can not only improve the permeability of reservoir rocks but also have important reference value for rock engineering in high-temperature environments.

ACS Style

Yan-Jun Shen; Jian-Shuai Hao; Xin Hou; Jiang-Qiang Yuan; Zhi-Peng Bai. Crack propagation in high-temperature granite after cooling shock: experiment and numerical simulation. Bulletin of Engineering Geology and the Environment 2021, 80, 5831 -5844.

AMA Style

Yan-Jun Shen, Jian-Shuai Hao, Xin Hou, Jiang-Qiang Yuan, Zhi-Peng Bai. Crack propagation in high-temperature granite after cooling shock: experiment and numerical simulation. Bulletin of Engineering Geology and the Environment. 2021; 80 (7):5831-5844.

Chicago/Turabian Style

Yan-Jun Shen; Jian-Shuai Hao; Xin Hou; Jiang-Qiang Yuan; Zhi-Peng Bai. 2021. "Crack propagation in high-temperature granite after cooling shock: experiment and numerical simulation." Bulletin of Engineering Geology and the Environment 80, no. 7: 5831-5844.

Original article
Published: 10 February 2021 in Geomechanics and Geophysics for Geo-Energy and Geo-Resources
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Granite at a high temperature can cause a decrease in strength and cracking when exposed to a rapid cooling shock. Therefore, the cooling shock method can be considered as a potential cracking technology to improve the energy exploitation efficiency. The thermal cracking damage of high-temperature granite after cooling shock induced by different low-temperature refrigerants were studied. Firstly, granite samples were heated to different targeted temperatures (i.e.100, 300, 500, and 700 °C). Then, all heated samples were respectively soaked in these refrigerants with different temperatures (i.e. 20, 0, − 10, − 20 and − 30 °C) or cooled in the air condition as a reference. When the cooling process ends, the effects of cooling shock on the strength characteristics and failure modes of high-temperature granites were respectively observed by acoustic wave, uniaxial compression test and the acoustic emission (AE) test. Some main conclusions are: (1) The high temperature granite p-wave velocity tends to decreases with the refrigerant temperature decreases. (2) The lower CaCl2 solution temperature is, the lower the peak strength. The specific performance is that the higher granite temperature, the more obvious the granite strength decreases after the cooling shock. (3) The curves under different temperature gradients performs from a “single/double peak” to a “multipeak” as the refrigerant temperature decreases. (4) The failure modes of granite subjected to different temperature gradients are obviously different, of which X-type shear failure is shown above 500 °C. These studies verify the strong effect of cooling shocks on high-temperature granite. Scholars can draw on the experience of cooling shock technology in the geothermal development of late-stage high-temperature rock masses.

ACS Style

Yanjun Shen; Jiangqiang Yuan; Xin Hou; Jianshuai Hao; Zhipeng Bai; Ting Li. The strength changes and failure modes of high-temperature granite subjected to cooling shocks. Geomechanics and Geophysics for Geo-Energy and Geo-Resources 2021, 7, 1 -18.

AMA Style

Yanjun Shen, Jiangqiang Yuan, Xin Hou, Jianshuai Hao, Zhipeng Bai, Ting Li. The strength changes and failure modes of high-temperature granite subjected to cooling shocks. Geomechanics and Geophysics for Geo-Energy and Geo-Resources. 2021; 7 (1):1-18.

Chicago/Turabian Style

Yanjun Shen; Jiangqiang Yuan; Xin Hou; Jianshuai Hao; Zhipeng Bai; Ting Li. 2021. "The strength changes and failure modes of high-temperature granite subjected to cooling shocks." Geomechanics and Geophysics for Geo-Energy and Geo-Resources 7, no. 1: 1-18.

Original
Published: 27 November 2020 in Heat and Mass Transfer
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The thermal conductivity (TC) of rock has a general application in safety assessment and engineering optimization of deep geological engineering practices such as geothermal mining and nuclear waste disposal. Determining the TC of rock by using a TC model is a convenient and effective method for such evaluation, and selecting a suitable TC model is key for ensuring accurate calculation results. In this study, we firstly select eight two-phase TC models to evaluate the applicability to sandstone. Secondly, the TC values of sandstones in various porous media such as air, water, and ice are measured by using the transient plane source (TPS) method, and the mineral composition and content were determined by using X-ray diffraction (XRD) and the Cross, Iddings, Pirsson, and Washington (CIPW) norm. Thirdly, the TC values of sandstones in different porous media are also calculated by using the eight models, and their deviations are analyzed to compare their applicability. Finally, by considering of the influence of pore structure on the rock TC, a new TC model referred to as the thermal resistance–connectivity (TRC) model is proposed for sandstone based on pore connectivity, and the mean deviation is compared with the previous model. Several results are obtained. Among the eight common models, the geometric mean model is found to be more accurate than other models regardless of all three states. In particular, for the porous medium filled with ice, the calculated value of the Geometric mean model had the most significant agreement with the measured value. In addition, the mean deviation of the TRC model for all three states is shown to be more consistent with the measured value than the eight models. Therefore, we recommended the TRC model for calculating the TC of sandstone. This study provides a novel method for determining the TC value for deep geological assessment.

ACS Style

Yanjun Shen; Xu Wang; Yongzhi Wang; Keping Zhou; Jinyuan Zhang; Huan Zhang; Jielin Li. Thermal conductivity models of sandstone: applicability evaluation and a newly proposed model. Heat and Mass Transfer 2020, 57, 985 -998.

AMA Style

Yanjun Shen, Xu Wang, Yongzhi Wang, Keping Zhou, Jinyuan Zhang, Huan Zhang, Jielin Li. Thermal conductivity models of sandstone: applicability evaluation and a newly proposed model. Heat and Mass Transfer. 2020; 57 (6):985-998.

Chicago/Turabian Style

Yanjun Shen; Xu Wang; Yongzhi Wang; Keping Zhou; Jinyuan Zhang; Huan Zhang; Jielin Li. 2020. "Thermal conductivity models of sandstone: applicability evaluation and a newly proposed model." Heat and Mass Transfer 57, no. 6: 985-998.

Short communication
Published: 13 September 2020 in Journal of Rock Mechanics and Geotechnical Engineering
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It is generally accepted that the uniaxial compressive strength (UCS) and P-wave velocity of rocks tend to decrease simultaneously with increasing temperature. However, based on a great number of statistical data and systematic analysis of the microstructure variation of rocks with temperature rising and corresponding propagation mechanism of elastic wave, the results show that (1) There are three different trends for the changes of UCS and P-wave velocity of sandstone when heated from room temperature (20 °C or 25 °C) to 800 °C: (i) Both the UCS and P-wave velocity decrease simultaneously; (ii) The UCS increases initially and then decreases, while the P-wave velocity decreases continuously; and (iii) The UCS increases initially and then fluctuates, while the P-wave velocity continuously decreases. (2) The UCS changes at room temperature–400 °C, 400 °C–600 °C, and 600 °C–800 °C are mainly attributed to the discrepancy of microstructure characteristics and quartz content, the transformation plasticity of clay minerals, and the balance between the thermal cementation and thermal damage, respectively. (3) The inconsistency in the trends of UCS and P-wave velocity changes is caused by the change of quartz content, phase transition of water and certain minerals. © 2020 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

ACS Style

Jinyuan Zhang; Yanjun Shen; Gengshe Yang; Huan Zhang; Yongzhi Wang; Xin Hou; Qiang Sun; Guoyu Li. Inconsistency of changes in uniaxial compressive strength and P-wave velocity of sandstone after temperature treatments. Journal of Rock Mechanics and Geotechnical Engineering 2020, 13, 143 -153.

AMA Style

Jinyuan Zhang, Yanjun Shen, Gengshe Yang, Huan Zhang, Yongzhi Wang, Xin Hou, Qiang Sun, Guoyu Li. Inconsistency of changes in uniaxial compressive strength and P-wave velocity of sandstone after temperature treatments. Journal of Rock Mechanics and Geotechnical Engineering. 2020; 13 (1):143-153.

Chicago/Turabian Style

Jinyuan Zhang; Yanjun Shen; Gengshe Yang; Huan Zhang; Yongzhi Wang; Xin Hou; Qiang Sun; Guoyu Li. 2020. "Inconsistency of changes in uniaxial compressive strength and P-wave velocity of sandstone after temperature treatments." Journal of Rock Mechanics and Geotechnical Engineering 13, no. 1: 143-153.

Original paper
Published: 07 August 2020 in International Journal of Fracture
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Cooling shock can be considered a potential method of causing the high-temperature rocks to crack and achieve the most efficient exploitation and utilization of geo-thermal energy in the future. However, it is important to accurately recognize the thermal cracking effect and the corresponding typical characteristics of cooling shock. Therefore, in this study, we conducted a systematic experiment on the effects of cooling shocks with different temperature gradients on the cracking of high-temperature granite. The granite samples were heated to 150, 350, 550, and 750 °C, and then injected with three kinds of refrigerants of 20, 0 and − 20 °C into the granite boreholes. Furthermore, the cracking characteristics of granite were compared by means of optical microscope. According to the experimental analysis, several conclusions could be obtained: (1) Compared with natural cooling conditions, cooling shocks of 20, 0, and − 20 °C resulted in no evident open cracks on the granite at 150 and 350 °C; however, the distribution of the micro-crack networks became denser with a decrease in the refrigerant temperature. (2) For the high-temperature granite samples at 550 and 750 °C, the effect of the cooling shock was significant, and localized open cracks could be observed; however, several differences were evident in the effect of granite cracking under different combinations of cooling shocks and high temperatures. For granite with the same temperature gradient, with the decrease in the refrigerant temperature, the number of inter-granular and trans-granular cracks increased, and the cooling shock enhanced the cracking effect. (3) The main factor of granite cracking was the anisotropy of the mineral particles affected by the temperature difference, in which a large amount of quartz was contained in the granite, and the effect of repeated phase transformation near 573 °C was remarkable. Moreover, with the temperature difference between the refrigerant and the heated samples increasing, the generated tensile forces in the outer edge of samples would increase rapidly, causing amounts of trans-granular cracks and leading to the denser micro-crack networks. This work can provide an experimental reference for understanding the effect of cooling shock on mechanical properties and cracking of high-temperature rocks.

ACS Style

Yan-Jun Shen; Xin Hou; Jiang-Qiang Yuan; Shao-Fei Wang; Chun-Hu Zhao. Thermal cracking characteristics of high-temperature granite suffering from different cooling shocks. International Journal of Fracture 2020, 225, 153 -168.

AMA Style

Yan-Jun Shen, Xin Hou, Jiang-Qiang Yuan, Shao-Fei Wang, Chun-Hu Zhao. Thermal cracking characteristics of high-temperature granite suffering from different cooling shocks. International Journal of Fracture. 2020; 225 (2):153-168.

Chicago/Turabian Style

Yan-Jun Shen; Xin Hou; Jiang-Qiang Yuan; Shao-Fei Wang; Chun-Hu Zhao. 2020. "Thermal cracking characteristics of high-temperature granite suffering from different cooling shocks." International Journal of Fracture 225, no. 2: 153-168.

Original paper
Published: 30 June 2020 in Bulletin of Engineering Geology and the Environment
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Cooling shock has a significant thermal deterioration (TD) on the physical and mechanical properties of rocks in high-temperature conditions, which is a critical concern for the engineering application of the cyclic hydraulic fracturing technique in an enhanced geothermal system (EGS). In this work, cooling shock tests were carried out on granite samples to evaluate the actual TD of high-temperature rocks by cooling shocks, and multiple test methods were used to explore the effect of TD on the corresponding physical and mechanical properties of high-temperature granite. Some core conclusions from the study are as follows: (1) The wave velocity and apparent resistivity (AR) can reflect the thermal damage effect of cooling shocks on high-temperature granite. Notably, the higher the temperature of granite, the more significant change in wave velocity and AR. (2) The stress-strain curve tends to be smooth with the granite temperature increases and the cooling shocks intensify, the quiet period of acoustic emission (AE) events is lengthened, and the number is gradually reduced. (3) The TD effect of the cooling shock tends to be more significant for the samples at temperatures above 550 °C, and the peak stress continues to decrease with cooling shock strengthen. Furthermore, thermal stress is the main cause of TD to high-temperature granite. This study has the potential to guide the use of the cooling shock effect in extraction applications of geothermal engineering.

ACS Style

Yanjun Shen; Xin Hou; Jiangqiang Yuan; Zhenhao Xu; Jianshuai Hao; Linjun Gu; Zhiyun Liu. Thermal deterioration of high-temperature granite after cooling shock: multiple-identification and damage mechanism. Bulletin of Engineering Geology and the Environment 2020, 79, 5385 -5398.

AMA Style

Yanjun Shen, Xin Hou, Jiangqiang Yuan, Zhenhao Xu, Jianshuai Hao, Linjun Gu, Zhiyun Liu. Thermal deterioration of high-temperature granite after cooling shock: multiple-identification and damage mechanism. Bulletin of Engineering Geology and the Environment. 2020; 79 (10):5385-5398.

Chicago/Turabian Style

Yanjun Shen; Xin Hou; Jiangqiang Yuan; Zhenhao Xu; Jianshuai Hao; Linjun Gu; Zhiyun Liu. 2020. "Thermal deterioration of high-temperature granite after cooling shock: multiple-identification and damage mechanism." Bulletin of Engineering Geology and the Environment 79, no. 10: 5385-5398.

Journal article
Published: 15 April 2020 in Construction and Building Materials
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Sufficient bonding at concrete–rock interfaces is an important prerequisite when designing supports using concrete or shotcrete. However, the bonding between concrete and rock is often affected by low temperatures in cold regions. This study focuses on the effects that freeze–thaw cycles have on meso-debonding at sandstone–concrete interfaces. The prepared sandstone-concretes composite materials were subjected to freeze–thaw cycles and nuclear magnetic resonance (NMR) test. The effects of the freeze–thaw cycles on sandstone–concrete composites and the interfacial pore changes are discussed in this paper. The extent of the interface-influencing zone (IIZ) and the process controlling interface debonding are described based on the results of those experiments. The three primary conclusions are as follows: (1) The volume of the micropores and macropores in sandstone increases with the freeze–thaw cycles; however, the volume of the mesopores decreases. (2) The IIZ lies in the sandstone, near the interface, and is accompanied by water enrichment. (3) From a mesoscopic point of view, the process of debonding in the sandstone-concrete is not initialized at the interface but occurs in the sandstone near the interface.

ACS Style

Yanjun Shen; Yongzhi Wang; Xin Wei; Hailiang Jia; Ruixin Yan. Investigation on meso-debonding process of the sandstone–concrete interface induced by freeze–thaw cycles using NMR technology. Construction and Building Materials 2020, 252, 118962 .

AMA Style

Yanjun Shen, Yongzhi Wang, Xin Wei, Hailiang Jia, Ruixin Yan. Investigation on meso-debonding process of the sandstone–concrete interface induced by freeze–thaw cycles using NMR technology. Construction and Building Materials. 2020; 252 ():118962.

Chicago/Turabian Style

Yanjun Shen; Yongzhi Wang; Xin Wei; Hailiang Jia; Ruixin Yan. 2020. "Investigation on meso-debonding process of the sandstone–concrete interface induced by freeze–thaw cycles using NMR technology." Construction and Building Materials 252, no. : 118962.

Journal article
Published: 10 March 2020 in Molecules
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Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

ACS Style

Tao Luo; Chi Zhang; Xiangtian Xu; Yanjun Shen; Hailiang Jia; Chaowei Sun. Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface. Molecules 2020, 25, 1251 .

AMA Style

Tao Luo, Chi Zhang, Xiangtian Xu, Yanjun Shen, Hailiang Jia, Chaowei Sun. Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface. Molecules. 2020; 25 (5):1251.

Chicago/Turabian Style

Tao Luo; Chi Zhang; Xiangtian Xu; Yanjun Shen; Hailiang Jia; Chaowei Sun. 2020. "Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface." Molecules 25, no. 5: 1251.

Journal article
Published: 17 October 2019 in Cold Regions Science and Technology
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In cold regions, the bonding strength of concrete–rock interface is considerably influenced by freeze–thaw (F–T) actions. However, accurate approaches to evaluate the influence of F–T cycles on interfacial strength are relatively few. In this study, a novel shearing fracture morphology method for reflecting the influence of F–T cycles on the bonding performances of concrete–rock interface is proposed. A three–dimensional (3D) laser scanning technology is firstly used to determine the interfacial roughness index and joint roughness coefficient (JRC). Thereafter, interfacial debonding tests after subjecting the samples to different F–T cycles (i.e., 0, 10, 20, 30, and 50) are performed using a slant shear test. Based on the measurements obtained by image processing technology (i.e., binarization and 3D reconstruction image observations), a novel shearing fracture morphology approach is proposed to reflect the interfacial morphology features and their residual concrete adhesion area at different F–T cycles. Moreover, the relationships among F–T cycles, interfacial fracture morphology, and shear strength are discussed. The conclusions drawn are as follows: (i) the interfacial bonding strength depends on the roughness and the cementing force between cement and mineral particles of granite; (ii) F–T cycles have a significant effect on the bonding performance of concrete–granite interface caused by the deterioration effects of cementation; (iii) the proportions of concrete adhesion, fracture morphology, and JRCs have positive correlations. This study provides a new approach for evaluating the influence of F–T actions on concrete–rock interfacial debonding features.

ACS Style

Yanjun Shen; Hongwei Yang; Jiami Xi; Yang Yang; Yongzhi Wang; Xin Wei. A novel shearing fracture morphology method to assess the influence of freeze–thaw actions on concrete–granite interface. Cold Regions Science and Technology 2019, 169, 102900 .

AMA Style

Yanjun Shen, Hongwei Yang, Jiami Xi, Yang Yang, Yongzhi Wang, Xin Wei. A novel shearing fracture morphology method to assess the influence of freeze–thaw actions on concrete–granite interface. Cold Regions Science and Technology. 2019; 169 ():102900.

Chicago/Turabian Style

Yanjun Shen; Hongwei Yang; Jiami Xi; Yang Yang; Yongzhi Wang; Xin Wei. 2019. "A novel shearing fracture morphology method to assess the influence of freeze–thaw actions on concrete–granite interface." Cold Regions Science and Technology 169, no. : 102900.

Journal article
Published: 16 July 2019 in Water
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Since large-scale agricultural irrigation began in the 1980s, 92 landslides have occurred around the South Jingyang Plateau during the past 40 years. The geological disaster and soil erosion have caused numerous casualties and substantial property loss. In this work, several field investigations are carried out to explore the soil erosion and mechanical mechanism of these irrigated shallow loess landslides on the South Jingyang Plateau. (1) We investigated the spatial distributions, types and developmental characteristics of loess landslides. (2) We surveyed and monitored seasonal agricultural irrigation features and groundwater changes in the area since the 1980s and found that irrigation is a significant factor influencing groundwater changes, soil erosion and even causing landslides to occur. (3) Based on the field investigation, the occurrence of these irrigated shallow loess landslides was generalized, and it was found that the core process was due to the liquefaction of softening zone. We carried out a static liquefaction test and verified that the natural loess was prone to liquefaction. (4) The three main reasons for shallow loess landslides in the South Jingyang Plateau were discussed. This study provides a valuable reference for achieving an understanding of the relationship between seasonal agricultural irrigation and the occurrence of loess landslides in the area as well as similar irrigated agricultural areas.

ACS Style

Rui-Xin Yan; Jian-Bing Peng; Qiang-Bing Huang; Li-Jie Chen; Chen-Yun Kang; Yan-Jun Shen. Triggering Influence of Seasonal Agricultural Irrigation on Shallow Loess Landslides on the South Jingyang Plateau, China. Water 2019, 11, 1474 .

AMA Style

Rui-Xin Yan, Jian-Bing Peng, Qiang-Bing Huang, Li-Jie Chen, Chen-Yun Kang, Yan-Jun Shen. Triggering Influence of Seasonal Agricultural Irrigation on Shallow Loess Landslides on the South Jingyang Plateau, China. Water. 2019; 11 (7):1474.

Chicago/Turabian Style

Rui-Xin Yan; Jian-Bing Peng; Qiang-Bing Huang; Li-Jie Chen; Chen-Yun Kang; Yan-Jun Shen. 2019. "Triggering Influence of Seasonal Agricultural Irrigation on Shallow Loess Landslides on the South Jingyang Plateau, China." Water 11, no. 7: 1474.

Original paper
Published: 03 June 2019 in Bulletin of Engineering Geology and the Environment
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In order to evaluate and compare the accurate activation energy variations of two kinds of deposited clays (i.e. non-organic clay and organic clay), thermo-gravimetric analysis (TGA) was firstly conducted to study the reaction characteristics of the two clay samples. Two periods of weight losses were observed according to each TGA curve for both clay samples. The first period happened due to water evaporation, while the second period was mainly caused by the composition reactions of clay minerals, especially influenced by the de-hydroxylation of kaolinite. An obvious phenomenon is that the organic clay with a high soil organic matter (SOM) has a higher activity energy. Then, four common kinetics models [i.e. the Coats-Redfern method, the Doyle integral method, the maximum rate method, and the distributed activation energy model (DAEM)] were used to calculate and compare the activation energy values. And the Doyle integral method and the DAEM method are considered as two recommended models to analyze the activation energy performance during thermal treatment. Some interesting conclusions can be summarized as: (1) The multi-period reactions of deposited clays during the heating process are common, especially for organic clay. It would be beneficial knowing its biomass resource feasibility concerning the second weight loss; (2) The high SOM has a significant influence on the potential energy unitization of deposited clays, while the variations of activity energy for deposited clays are influenced by the mineral compositions and microstructure features; (3) It is possible to evaluate the accurate activity energy of deposited clays combined with TGA tests and two recommended models (i.e. the Doyle integral method and DAEM method).

ACS Style

Rui-Xin Yan; Jian-Bing Peng; Yan-Jun Shen; Yuliang Zhang; Lin-Jun Gu; Shao-Kai Wang. Evaluation on activation energy of deposited clay based on thermo-gravimetric analysis (TGA) and four kinetics models. Bulletin of Engineering Geology and the Environment 2019, 79, 371 -382.

AMA Style

Rui-Xin Yan, Jian-Bing Peng, Yan-Jun Shen, Yuliang Zhang, Lin-Jun Gu, Shao-Kai Wang. Evaluation on activation energy of deposited clay based on thermo-gravimetric analysis (TGA) and four kinetics models. Bulletin of Engineering Geology and the Environment. 2019; 79 (1):371-382.

Chicago/Turabian Style

Rui-Xin Yan; Jian-Bing Peng; Yan-Jun Shen; Yuliang Zhang; Lin-Jun Gu; Shao-Kai Wang. 2019. "Evaluation on activation energy of deposited clay based on thermo-gravimetric analysis (TGA) and four kinetics models." Bulletin of Engineering Geology and the Environment 79, no. 1: 371-382.

Journal article
Published: 31 May 2019 in Energies
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It is valuable to observe the influence of different cooling methods on the exploitation of geothermal energy and breaking hard rocks in deep geo-engineering. In this work, the effects of different cooling shock treatments on high temperature granite are discussed. First, perforated 100-mm-side cubic biotite adamellite samples were heated to four targeted temperatures (150 °C, 350 °C, 550 °C, and 750 °C). Then, anti-freeze solutions were compounded to produce the different cooling shock effects (20 °C, 0 °C, and −30 °C) by adjusting the calcium chloride solution concentration, and these anti-freeze solutions were injected rapidly into the holes to reflect the rapid cooling shock of high-temperature granite. Finally, the temperature variations and crack expansions of high-temperature granite under different cooling shock treatments were analyzed and the cooling shock cracking mechanism is discussed briefly. The main results can be summarized as: (1) The high temperature granite exposed to the cooling shock exhibited a "rapid cooling + rapid heating" change during the first 5 min. Due to the cooling shock, the total temperature was significantly lower than the natural cooling until 120 min later. (2) Below 350 °C, the macrocracking effect was not significant, and the sample reflected a certain range of uniform microcracks around the injection hole, while the macrocracks tended to be obvious above 550 °C. Moreover, as the refrigerant temperature decreased, the local distribution characteristics of the macrocracking became more obvious. (3) Based on the analysis of the dynamic heat balance, the undulation and width of the cracks around the heat balance zone were stable, but the numbers and widths of cracks near the hole wall and the side of the sample were visibly increased. This study extends our understanding of the influence of cooling shock on granite cracking.

ACS Style

Yan-Jun Shen; Xin Hou; Jiang-Qiang Yuan; Chun-Hu Zhao. Experimental Study on Temperature Change and Crack Expansion of High Temperature Granite under Different Cooling Shock Treatments. Energies 2019, 12, 2097 .

AMA Style

Yan-Jun Shen, Xin Hou, Jiang-Qiang Yuan, Chun-Hu Zhao. Experimental Study on Temperature Change and Crack Expansion of High Temperature Granite under Different Cooling Shock Treatments. Energies. 2019; 12 (11):2097.

Chicago/Turabian Style

Yan-Jun Shen; Xin Hou; Jiang-Qiang Yuan; Chun-Hu Zhao. 2019. "Experimental Study on Temperature Change and Crack Expansion of High Temperature Granite under Different Cooling Shock Treatments." Energies 12, no. 11: 2097.

Journal article
Published: 12 April 2019 in Construction and Building Materials
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The good bonding in a concrete-rock interface is an important premise to perform the supporting functions of concrete and shotcrete. However, the bonding strength of a concrete-rock interface is influenced by many factors such as rock mineral composition and textural features, surface roughness, interface treatments, and concrete mixture and its casting technique. In this study, we focused on the effects of surface roughness and hydrophilicity on the bonding performances of concrete-granite interface. First, we expressed these two interfacial parameters (i.e., joint roughness coefficient (JRC) and contact angle (CA)) quantitatively using fine measurement methods. Subsequently, after the concrete-granite composites were prepared, a series of interfacial slant shearing experiments of concrete-granite composites were performed for different JRC and CA values. Finally, the relationship between bonding strength and interfacial features were discussed, and a two-element interfacial shear model for the concrete-rock composite was proposed based on the experimental tests and theoretical derivation. Three primary outcomes are as follows: (1) the bonding strength always increases with the JRC, whether the interface is hydrophilic or hydrophobic. Simultaneously, the bonding strengths of hydrophilic interfaces are relatively better than those of hydrophobic interfaces for the same JRC value. (2) A coupling effect between surface roughness and hydrophilicity should exist on the bonding strength of the concrete-rock interface. In particular, the more severe the interfacial roughness, the weaker is the influence of hydrophilicity on the bonding strength. (3) It is significant to comprehensively consider the effects of surface features and the adhesion of concrete to reflect the bonding strength of the concrete-granite composite. The results of the proposed model considering these properties are in good agreement with the experimental values. This work provides a reference for understanding the bonding strength changes in concrete-rock interface owing to the effects of interfacial properties.

ACS Style

Yanjun Shen; Yongzhi Wang; Yang Yang; Qiang Sun; Tao Luo; Huan Zhang. Influence of surface roughness and hydrophilicity on bonding strength of concrete-rock interface. Construction and Building Materials 2019, 213, 156 -166.

AMA Style

Yanjun Shen, Yongzhi Wang, Yang Yang, Qiang Sun, Tao Luo, Huan Zhang. Influence of surface roughness and hydrophilicity on bonding strength of concrete-rock interface. Construction and Building Materials. 2019; 213 ():156-166.

Chicago/Turabian Style

Yanjun Shen; Yongzhi Wang; Yang Yang; Qiang Sun; Tao Luo; Huan Zhang. 2019. "Influence of surface roughness and hydrophilicity on bonding strength of concrete-rock interface." Construction and Building Materials 213, no. : 156-166.

Journal article
Published: 09 August 2018 in Cold Regions Science and Technology
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The thermal conductivity (TC) of rocks is influenced by a number of environmental factors including temperature, moisture content, and pressure. A series of experiments are presented in this work to address the influence of temperature both sides of the freezing point 0 °C as well as moisture content on sandstone TC values. All of the specimens discussed were collected from a coal mine shaft excavation using the artificial ground freezing (AGF) method. Thus, TC values of 32 pairs of medium grained sandstone and 21 pairs of coarse grained sandstone specimens were measured at temperatures ranging between −30 °C and 50 °C. The results show that TC values tend to increase as temperature decreases regardless of whether specimens are dry or water-saturated. It is also the case, however, that water-saturated specimens commonly have higher TC values than their dried counterparts at different target temperatures, especially at the range of between 5 °C and − 10 °C, while TC values of water-saturated specimens exhibited rapid increases. This phenomena also shows a good agreement with the deflection zone presented in Raman spectral peak values, clear evidence for the water-ice phase transition period.

ACS Style

Yan-Jun Shen; Yong-Zhi Wang; Xiao-Dong Zhao; Geng-She Yang; Hai-Liang Jia; Teng-Long Rong. The influence of temperature and moisture content on sandstone thermal conductivity from a case using the artificial ground freezing(AGF) method. Cold Regions Science and Technology 2018, 155, 149 -160.

AMA Style

Yan-Jun Shen, Yong-Zhi Wang, Xiao-Dong Zhao, Geng-She Yang, Hai-Liang Jia, Teng-Long Rong. The influence of temperature and moisture content on sandstone thermal conductivity from a case using the artificial ground freezing(AGF) method. Cold Regions Science and Technology. 2018; 155 ():149-160.

Chicago/Turabian Style

Yan-Jun Shen; Yong-Zhi Wang; Xiao-Dong Zhao; Geng-She Yang; Hai-Liang Jia; Teng-Long Rong. 2018. "The influence of temperature and moisture content on sandstone thermal conductivity from a case using the artificial ground freezing(AGF) method." Cold Regions Science and Technology 155, no. : 149-160.

Journal article
Published: 04 July 2018 in Energies
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Macroscopic properties of sandstone are commonly attributed to the degradation of its microstructure during heating treatment processes. However, few previous studies have focused on comprehensive observations on how the microstructure of sandstone changes with temperature. In this study, a kind of sandstone containing quartz, albite, calcite, and laumontite (little), was collected from Linyi (Shandong Province, China) to observe the microstructure degradation changes with temperature by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and thermo-gravimetric analyses (TGA). Firstly, 10 groups of sandstone samples were heated from 25 °C to 900 °C. Then, some core micro-parameters including lattice constant, full width at half maximum (FWHM), micro-strain, dislocation density, TGA curve changes and failure characteristic of the mineral were analyzed comprehensively. Finally, the underlying mechanism causing the microscopic thermal damage at different temperature intervals was also discussed. The results showed that: (1) quartz, the framework component of this sandstone, underwent an α- to β-phase change over the temperature range from 400 °C to 600 °C. This phenomenon caused the lattice constant, micro-strain, dislocation density and TGA curve to decrease sharply during this interval, leading to the microstructure deterioration of sandstone; (2) calcite underwent a decomposition reaction between 600 °C and 800 °C, and resulted in the XRD pattern peak, lattice constant, micro-strain and TGA curve dropping continuously. It destroyed further the internal microstructure of sandstone and produced numerous inter-granular cracks around quartz crystals; (3) further examination found that the decomposition reactions of minerals presented non-synchronized characteristics due to the different sensitivities of minerals to temperature, which led to thermal stress, thermal fracturing of minerals, and thermal reactions happening in different temperature intervals.

ACS Style

Yan-Jun Shen; Yuliang Zhang; Feng Gao; Geng-She Yang; Xing-Ping Lai. Influence of Temperature on the Microstructure Deterioration of Sandstone. Energies 2018, 11, 1753 .

AMA Style

Yan-Jun Shen, Yuliang Zhang, Feng Gao, Geng-She Yang, Xing-Ping Lai. Influence of Temperature on the Microstructure Deterioration of Sandstone. Energies. 2018; 11 (7):1753.

Chicago/Turabian Style

Yan-Jun Shen; Yuliang Zhang; Feng Gao; Geng-She Yang; Xing-Ping Lai. 2018. "Influence of Temperature on the Microstructure Deterioration of Sandstone." Energies 11, no. 7: 1753.

Original
Published: 15 May 2018 in Heat and Mass Transfer
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A series of experiments were carried out to measure the damage characteristics of two common sedimentary rocks of limestone and sandstone at temperatures ranging from −30 °C to 1000 °C The apparent thermal conductivity, thermal diffusivity and specific heat capacity were investigated respectively. Then, several discrepancy reasons for the damage characteristics and thermo-physical properties of limestone and sandstone were probed. The results show that water migration and phase transition are two core factors for the frost damage and thermal behaviors improvement during the cooling process(20 °C → −30 °C).The heating process (20 °C → 1000 °C) was divided into three stages of 20 °C → 200 °C, 200 °C → 600 °Cand 600 °C → 1000 °C. The first stage was closely related to pore-water evaporation, and the next two stages were attributed to the thermal reactions of mineral partials. The mineral decomposition tended to be intensified and resulted in the interior damage or even the accelerated degradation of thermal properties until at a threshold temperature of 600 °C. In essential, the structural features and the sensitivity of mineral composition to temperature were two mainly influential factors on the damage effects and heat conduct of the sedimentary rocks during variations in environmental temperature.

ACS Style

Yanjun Shen; Yang Yang; Gengshe Yang; Xin Hou; Wanjun Ye; Zhemin You; Jiami Xi. Damage characteristics and thermo-physical properties changes of limestone and sandstone during thermal treatment from −30 °C to 1000 °C. Heat and Mass Transfer 2018, 54, 3389 -3407.

AMA Style

Yanjun Shen, Yang Yang, Gengshe Yang, Xin Hou, Wanjun Ye, Zhemin You, Jiami Xi. Damage characteristics and thermo-physical properties changes of limestone and sandstone during thermal treatment from −30 °C to 1000 °C. Heat and Mass Transfer. 2018; 54 (11):3389-3407.

Chicago/Turabian Style

Yanjun Shen; Yang Yang; Gengshe Yang; Xin Hou; Wanjun Ye; Zhemin You; Jiami Xi. 2018. "Damage characteristics and thermo-physical properties changes of limestone and sandstone during thermal treatment from −30 °C to 1000 °C." Heat and Mass Transfer 54, no. 11: 3389-3407.

Journal article
Published: 01 May 2018 in Engineering Geology
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ACS Style

Yan-Jun Shen; Geng-She Yang; Hong-Wei Huang; Teng-Long Rong; Hai-Liang Jia. The impact of environmental temperature change on the interior temperature of quasi-sandstone in cold region: Experiment and numerical simulation. Engineering Geology 2018, 239, 241 -253.

AMA Style

Yan-Jun Shen, Geng-She Yang, Hong-Wei Huang, Teng-Long Rong, Hai-Liang Jia. The impact of environmental temperature change on the interior temperature of quasi-sandstone in cold region: Experiment and numerical simulation. Engineering Geology. 2018; 239 ():241-253.

Chicago/Turabian Style

Yan-Jun Shen; Geng-She Yang; Hong-Wei Huang; Teng-Long Rong; Hai-Liang Jia. 2018. "The impact of environmental temperature change on the interior temperature of quasi-sandstone in cold region: Experiment and numerical simulation." Engineering Geology 239, no. : 241-253.

Journal article
Published: 13 July 2017 in Environmental Earth Sciences
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ACS Style

Yanjun Shen; Guangli Xu; Jiangnan Yi. A systematic engineering geological evaluation of diabase dikes exposed at the underground caverns of Dagangshan hydropower station, Southwest China. Environmental Earth Sciences 2017, 76, 1 .

AMA Style

Yanjun Shen, Guangli Xu, Jiangnan Yi. A systematic engineering geological evaluation of diabase dikes exposed at the underground caverns of Dagangshan hydropower station, Southwest China. Environmental Earth Sciences. 2017; 76 (14):1.

Chicago/Turabian Style

Yanjun Shen; Guangli Xu; Jiangnan Yi. 2017. "A systematic engineering geological evaluation of diabase dikes exposed at the underground caverns of Dagangshan hydropower station, Southwest China." Environmental Earth Sciences 76, no. 14: 1.