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Experimental and numerical study of coal mechanical properties during coalification jumps

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Frontiers of Earth science 2023年第1期17卷 45-57页

作者： Qiang HUANG Xuehai FU Jian SHEN Qiangling YAO Ming CHENG Key Laboratory of Coalbed Methane Resources&Reservoir Formation Process(Ministry of Education) China University of Mining and TechnologyXuzhou 221116China School of Mines Key Laboratory of Deep Coal Resource MiningMinistry of EducationChina University of Mining&TechnologyXuzhou 221116China

The mechanical characteristics of coal reservoirs are important parameters in the hydraulic fracturing of *** this study,coal samples of different ranks were collected from 12 coal mines located in Xinjiang and shanxi,*** coal ranks were identified with by the increased Maximum vitrine reflectance(Ro,max)*** triaxial compression experiments were performed to determine the confining pressure effect on the mechanical properties of coal samples of different *** numerical approaches,including the power function,arctangent,and exponential function models,were used to find the correlation between coal elastic modulus and the confining *** fitting equations of compressive strength and elastic modulus of coal ranks were constructed under different confining *** results showed that the coal compressive strength of different ranks has a positive linear correlation with the confining *** coal elastic modulus and confining pressure showed an exponential ***’s ratio of coal and confining pressure show negative logarithmic *** stress sensitivity of the coal elastic modulus decreases with the increase of confining *** coalification jump identifies that the compressive strength,elastic modulus,and stress sensitivity coefficient of coal have a polynomial relationship with the increase of coal *** inflection points in coalification at Ro,max=0.70%,1.30%,and 2.40%,are the first,second,and third coalification *** findings provide significant support to coal fracturing during CBM production.

关键词： compressive strength elastic modulus confining pressure Poisson’s ratio coalification jump

Mechanism and control technology of strong ground pressure behaviour induced by high-position hard roofs in extra-thick coal seam mining

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International Journal of Mining science and technology 2022年第3期32卷 499-511页

作者： Chao Pan Binwei Xia Yujun Zuo Bin Yu Changnan Ou Mining College Guizhou UniversityGuiyang 550025China National&Local Joint Engineering Laboratory of Gas Drainage in Complex Coal Seam Chongqing UniversityChongqing 400044China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China

This work aimed at revealing the mechanism of strong ground pressure behaviour(SGPB)induced by high-position hard roof(HHR).Based on the supporting structures model of HHR,a modified voussoir beam mechanical model for HHR was established by considering the gangue support coefficient,through which the modified expressions of limit breaking span and breaking energy of HHR were *** with the relationship between the dynamic-static loading stress of supporting body(hydraulic support and coal wall)and its comprehensive supporting strength,the criteria of ground pressure behaviour(GPB)induced by HHR were *** types of Ⅰ_(1),Ⅰ_(2),Ⅱ_(1),andⅡ_(2) of GPB were *** showed that types Ⅰ_(1) and Ⅰ_(2) were the main forms of SGPB in extra-thick coal seam *** main manifestation of SGPB was static stress,which was mainly derived from the instability of HHR rather than ***,an innovative control technology was proposed,which can weaken static load by vertical-well separated fracturing *** research results have been successfully applied to the 8101 working face in Tashan coal mine,shanxi Province,*** results of a digital borehole camera observation and stress monitoring proved the rationality of the GPB *** control technology was successful,paving the way for new possibilities to HHR control for safety mining.

关键词： Extra thick coal seam High-position hard roof Strong ground pressure behaviour Supporting structures Criteria of ground pressure behaviour Controlling effects

Investigation of lateral spreading current in the 4H-SiC Schottky barrier diode chip

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Journal of Semiconductors 2021年第11期42卷 73-78页

作者： Xi Wang Yiwen Zhong Hongbin Pu Jichao Hu Xianfeng Feng Guowen Yang Department of Electronic Engineering Xi'an University of TechnologyXi'an 710048China Xi’an Key Laboratory of power Electronic Devices and High Efficiency Power Conversion Xi’an 710048China Sanli Intelligent Electric Co. LtdXi’an 712000China

Lateral current spreading in the 4H-SiC Schottky barrier diode(SBD)chip is *** 4H-SiC SBD chips with the same vertical parameters are simulated and *** results indicate that there is a fixed spreading resistance at on-state in current spreading region for a specific *** linear specific spreading resistance at the on-state is calculated to be 8.6Ω/cm in the fabricated *** proportion of the lateral spreading current in total forward current(Psp)is related to anode voltage and the chip *** is increased with the increase in the anode voltage during initial on-state and then tends to a stable *** stable values of Psp of the two fabricated chips are 32%and 54%.Combined with theoretical analysis,the proportion of the terminal region and scribing trench in a whole chip(Ksp)is also calculated and compared with *** Ksp values of the two fabricated chips are calculated to be 31.94%and 57.75%.The values of Ksp and Psp are close with each other in a specific *** calculated Ksp can be used to predict that when the chip area of SiC SBD becomes larger than 0.5 cm2,the value of Psp would be lower than 10%.

关键词： 4H-SiC Schottky barrier diode lateral spreading current