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| 1 | Experimental study on the infrared precursor characteristics of gas-bearing coal failure under loading显示文摘The stress and gas pressure in deep coal seams are very high,and instability and failure rapidly and intensely occur.It is important to study the infrared precursor characteristics of gas-bearing coal instability and failure.In this paper,a self-developed stress-gas coupling failure infrared experimental system was used to analyse the infrared radiation temperature(IRT)and infrared thermal image precursor characteristics of gas-free coal and gas-bearing coal.The changes in the areas of the infrared temperature anomalous precursor regions and the effect of the gas on the infrared precursors were examined.The results show that high-temperature anomalous precursors arise mainly when the gas-free coal fails under loading,whereas the gas-bearing coal has high-temperature and low-temperature anomalous precursors.The area of the high-temperature anomalous precursor is approximately 30%–40%under gasbearing coal unstable failure,which is lower than the 60%–70%of the gas-free coal.The area of the low-temperature abnormal precursor is approximately 3%–6%,which is higher than the 1%–2%of the gas-free coal.With increasing gas pressure,the area of the high-temperature anomalous precursor gradually decreases,and the area of the low-temperature anomalous precursor gradually increases.The highand low-temperature anomalous precursors of gas-bearing coal are mainly caused by gas desorption,volume expansion,and thermal friction.The presence of gas inhibits the increase in IRT on the coal surface and increases the difficulty of infrared radiation(IR)monitoring and early warning for gas-bearing coal. | Shan Yin Zhonghui Li Dazhao Song Xueqiu He Liming Qiu Quan Lou He Tian | 2021 | International Journal of Mining Science and Technology2021，31，5： | 4 |
| 2 | Early warning of coal dynamic disaster by precursor of AE and EMR'quiet period'显示文摘Efcient and accurate monitoring and early warning of coal dynamic disaster and other disasters can provide guarantee for the efcient operation of mine transportation system.However,the traditional threshold early warning method often fails to warning some accidents.To address above issues,a new early warning method was proposed based on'quiet period'phenomenon of AE and EMR during fracture.It is found that,a'quiet period'of AE and EMR was present before the load reaches the peak stress,which could be used as one of the precursors to warn the imminent failure of coal and rock specimens.MS and AE signals increased abnormally followed by the phenomenon of'quiet period'before the occurrence of coal dynamic disaster on site,and the decrease of MS events in the'quiet period'is about 57%–88%compared with that in previous abnormal increase stage.During the damage evolution of coal and rock,'quiet period'phenomenon usually occurred at 85%–90%of the peak stress,where the slope of damage parameter curve is almost zero.The'quiet period'of the AE-EMR signals and the low change rate of damage parameter before failure provide a theoretical foundation for the coal dynamic disaster warning based on the'quiet period'precursor found in MS-AE-EMR monitoring system.These fndings will help reduce the number of under-reported events and improve early warning accuracy. | Shengquan He Mengli Qin Liming Qiu Dazhao Song Xiufeng Zhang | 2022 | International Journal of Coal Science & Technology2022，9，3： | 1 |
| 3 | A dynamic ejection coal burst model for coalmine roadway collapse显示文摘In this study,we established a dynamic ejection coal burst model for a coalmine roadway subject to stress,and held that the stress concentration zone at the roadway side is the direct energy source of this ejection.The formation and development of such burst undergoes three stages:(1)instability and propagation of the cracks in the stress concentration zone,(2)emerging of a layered energy storage structure in the zone,and(3)ejection of coal mass or coal burst due to instability.Moreover,we figured out the initial strength of periodic cracks is parallel to the maximal dominant stress direction in the stress concentration zone and derived from the damage strain energy within the finite area of the zone based on the Griffith energy theory.In addition,we analyzed the formation process of the layered energy storage structure in the zone,simplified it as a simply supported restraint sheet,and calculated the minimum critical load and the internally accumulated elastic energy at the instable state.Furthermore,we established a criterion for occurrence of the coal burst based on the variational principle,and analyzed the coal mass ejection due to instability and coal burst induced by different intensity disturbances.At last,with the stratum conditions of Junde Coalmine as the model prototype,we numerically simulated the load displacement distribution of the stress concentration zone ahead of the working face disturbed by the main roof-fracture-induced dynamic load during the mining process as well as their varying characteristics,and qualitatively verified the above model. | Dazhao Song Xueqiu He Enyuan Wang Zhenlei Li Menghan Wei Hongwei Mu | 2019 | International Journal of Mining Science and Technology2019，29，4： | 1 |
| 4 | AFM characterization of surface mechanical and electrical properties of some common rocks显示文摘The characterization of micro-surface mechanical and electrical properties of the natural rock materials remains inadequate,and their macroscopic performance can be better comprehended by investigating the surface properties.With this purpose,the present research focuses on characterizing the microsurface morphology,Derjaguin-Muller-Toporov(DMT)modulus,adhesion,and potential of granite,shale,and limestone by employing the atomic force microscope(AFM)as a pioneer attempt.The results show that the micro-surface morphology of the rock fluctuates within hundreds of nanometers,among which the granite micro-surface is comparatively the smoothest,followed by limestone.The morphology of the shale is the roughest,indicating that the regional difference of shale micro-surface is dominant.The distribution of the adhesion on rock micro-surface is uneven;the average adhesion of eight measuring areas for shale is 23.93 n N,accounting for three times of granite and limestone,while the surface DMT modulus of shale is relatively lower than granite and limestone.It is inferred from the obtained results that higher surface adhesion is helpful to the gas adsorption of shale,and the lower surface DMT(elastic)modulus is useful to the formation of fractures and pores.Thus,these two are the micromechanical basis of shale gas adsorption.Additionally,introducing a method to reduce the surface adhesion will benefit the exploration of unconventional resources such as shale gas.The micro-surface of the three types of rocks all shows electricity,with average potential ranging from tens of millivolts to hundreds of millivolts.Besides,the micro-surface potential of the rocks are heterogeneous,and both positive and negative points can be found.The existence and uneven distribution of micro-surface potential provide a robust physical basis for the electromagnetic radiation generated by rock fracture under loading.This study offers a new method for revealing the adsorption characteristics of unconventional gas reservoir rocks and the electromagnetic radiation mechanism of the rock fracture. | Xianghui Tian Xueqiu He Dazhao Song Zhenlei Li Majid Khan Huifang Liu Liming Qiu | 2022 | International Journal of Mining Science and Technology2022，32，2： | 1 |
| 5 | Direct laser writing breaking diffraction barrier based on two-focus parallel peripheralphotoinhibition lithography显示文摘Direct laser writing(DLW)enables arbitrary three-dimensional nanofabrication.However,the diffraction limit poses a major obstacle for realizing nanometer-scale features.Furthermore,it is challenging to improve the fabrication efficiency using the currently prevalent single-focal-spot systems,which cannot perform high-throughput lithography.To overcome these challenges,a parallel peripheral-photoinhibition lithography system with a sub-40-nm two-dimensional feature size and a sub-20-nm suspended line width was developed in our study,based on two-photon polymerization DLW.The lithography efficiency of the developed system is twice that of conventional systems for both uniform and complex structures.The proposed system facilitates the realization of portable DLW with a higher resolution and throughput. | Dazhao Zhu Liang Xu Chenliang Ding Zhenyao Yang Yiwei Qiu Chun Cao Hongyang He Jiawei Chen Mengbo Tang Lanxin Zhan Xiaoyi Zhang Qiuyuan Sun Chengpeng Ma Zhen Wei Wenjie Liu Xiang Fu Cuifang Kuang Haifeng Li Xu Liu | 2022 | Advanced Photonics2022，4，6： | 1 |
| 6 | A novel high-voltage solid-state switch based on the SiC MOSFET series and its overcurrent protection显示文摘All-solid-state switches are one of the core components of pulsed power supply systems.However,the voltage level of a single switch is limited.By optimizing the chip structure,the voltage level of a single switch can be improved.Due to the immaturity of the production process and the positive correlation between the blocking voltage and the onresistance of the switch,it is difficult to improve the blocking voltage and the continuous forward current of a single switch simultaneously.The series-connected switch is a way to increase the switch's blocking voltage without reducing the switch's continuous forward current.Magnetically coupled isolated drive and resistor-capacitor forced voltage equalization techniques are investigated to increase the blocking voltage of the switches using multiple SiC metal-oxide-semiconductor field-effect transistors(MOSFETs)in series connections.Meanwhile,a special overcurrent protection scheme is designed to improve the reliability of the series-connected switch.Finally,a high-voltage solid-state switch is developed based on the SiC MOSFET series connections,whose output pulse width is adjustable from 20 to 300μs,frequency is adjustable from 1 Hz to 3 kHz,the maximum output voltage can reach 57 kV(1 Hz),and the overcurrent protection time is about 1μs. | Dazhao He Wenjie Sun Yixin Liao Penghao Zhang Liang Yu Shoulong Dong Chenguo Yao Xin liu | 2023 | High Voltage2023，8，4： | 1 |
| 7 | A method to predict rockburst using temporal trend test and its application显示文摘Rockbursts have become a significant hazard in underground mining,underscoring the need for a robust early warning model to ensure safety management.This study presents a novel approach for rockburst prediction,integrating the Mann-Kendall trend test(MKT)and multi-indices fusion to enable real-time and quantitative assessment of rockburst hazards.The methodology employed in this study involves the development of a comprehensive precursory index library for rockbursts.The MKT is then applied to analyze the real-time trend of each index,with adherence to rockburst characterization laws serving as the warning criterion.By employing a confusion matrix,the warning effectiveness of each index is assessed,enabling index preference determination.Ultimately,the integrated rockburst hazard index Q is derived through data fusion.The results demonstrate that the proposed model achieves a warning effectiveness of 0.563 for Q,surpassing the performance of any individual index.Moreover,the model’s adaptability and scalability are enhanced through periodic updates driven by actual field monitoring data,making it suitable for complex underground working environments.By providing an efficient and accurate basis for decision-making,the proposed model holds great potential for the prevention and control of rockbursts.It offers a valuable tool for enhancing safety measures in underground mining operations. | Yarong Xue Zhenlei Li Dazhao Song Xueqiu He Honglei Wang Chao Zhou Jianqiang Chen Aleksei Sobolev | 2024 | Journal of Rock Mechanics and Geotechnical Engineering2024，16，3： | 0 |
| 8 | Characteristics of electromagnetic vector field generated from rock fracturing显示文摘Rock fracturing is often accompanied by electromagnetic phenomenon.As a vector field,in addition to the intensity that is widely concerned,the generated electromagnetic field also has obvious direction-ality.To this end,a set of electromagnetic antennas capable of simultaneous three-axis measurement is used to monitor the electromagnetic vector field generated from rock fracturing based on Brazilian tests.The signal amplitude on each axis can represent the magnitude of actual magnetic flux density component on the three axes.The intensity and directional characteristics of electromagnetic signals received at different positions are studied using vector synthesis.The directionality of electromagnetic radiation measured using a three-axis electromagnetic antenna shows that the direction of the magnetic flux intensity generated by rock fracturing tends to be parallel to the crack surface,and the measured signal intensity is greater in a direction closer to the crack surface. | Menghan Wei Dazhao Song Xueqiu He Quan Lou Liming Qiu Zhenlei Li | 2023 | Journal of Rock Mechanics and Geotechnical Engineering2023，15，2： | 0 |
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