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Experimental and theoretical investigation on mechanisms performance of the rock-coal-bolt(RCB)composite system

International Journal of Mining Science and Technology 2020年第6期30卷 759-768页

作者： Genshui Wu weijian yu Jianping Zuo Shaohua Du School of Mechanics and Civil Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology-BeijingBeijing 100083China School of Resource&Environment and Safety Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Resources and Safety Engineering Central South UniversityChangsha 410083China

For coal mines,rock,coal,and rock bolt are the critical constituent materials for surrounding rock in the underground *** stability of the“rock-coal-bolt”(RCB)composite system is affected by the structure and fracture of the coal-rock *** rock bolts installed on the rock,more complex condition of the engineering stress environment will be(tensile-shear composite stress is principal).In this paper,experimental analysis and theoretical verification were performed on the RCB composite system with different *** results revealed that the failure of the rock-coal(RC)composite specimen was caused by tensile and shear *** anchoring,the reinforcement body formed inside the composite system limits the area where the crack could occur in the ***,shearing damage occurred only around the bolt,and the stress-strain curve presented a better post-peak mechanical *** mechanical mechanism of the bolt under the combined action of tension and shear stress was ***,a rock-coal-bolt tensile-shear mechanical(RCBTSM)model was *** relationship(similar to the exponential function)between the bolt tensile-shear stress and the angle was ***,the influences of the dilatancy angle and bolt diameter of the RCB composite system were also considered and *** of the bolts are subjected to the tensile-shearing action in the post-peak *** implications of these results for engineering practice indicated that the bolts of the RCB composite system should be prevented from entering the limit shearing state early.

关键词： Thin coal seam Coal and rock roadway Bolt Tension-shear failure “Rock-coal-bolt”composite system

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A batch microfabrication of a self-cleaning,ultradurable electrochemical sensor employing a BDD film for the online monitoring of free chlorine in tap water

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Microsystems & Nanoengineering 2022年第2期8卷 85-96页

作者： Jiawen Yin Wanlei Gao weijian yu Yihua Guan Zhenyu Wang Qinghui Jin Faculty of Electrical Engineering and Computer Science Ningbo University315211 NingboP.R.China State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences200050 ShanghaiP.R.China

Free chlorine is one of the key water quality parameters in tap ***,a free chlorine sensor with the characteristics of batch processing,durability,antibiofouling/antiorganic passivation and in situ monitoring of free chlorine in tap water continues to be a challenging *** this paper,a novel silicon-based electrochemical sensor for free chlorine that can self-clean and be mass produced via microfabrication technique/MEMS(Micro-Electro-Mechanical System)is proposed.A liquid-conjugated Ag/AgCI reference electrode is fabricated,and electrochemically stable BDD/Pt is employed as the working/counter electrode to verify the effectiveness of the as-fabricated sensor for free chlorine *** sensor demonstrates an acceptable limit of detection(0.056 mg/L)and desirable linearity(R^(2)=0.998).Particularly,at a potential of+2.5 V,hydroxyl radicals are generated on the BBD electrode by electrolyzing water,which then remove the organic matter attached to the surface of the sensor though an electrochemical digestion *** performance of the fouled sensor recovers from 50.2 to 94.1%compared with the initial state after self-cleaning for 30 *** addition,by employing the MEMS technique,favorable response consistency and high reproducibility(RSD<4.05%)are observed,offering the opportunity to mass produce the proposed sensor in the future.A desirable linear dependency between the pH,temperature,and flow rate and the detection of free chlorine is observed,ensuring the accuracy of the sensor with any hydrologic *** interesting sensing and selfcleaning behavior of the as-proposed sensor indicate that this study of the mass production of free chlorine sensors by MEMS is successful in developing a competitive device for the online monitoring of free chlorine in tap water.

关键词： chlorine batch electrode

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Failure mechanism of Mesozoic soft rock roadway in Shajihai coal mine and its surrounding rock control

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International Journal of Mining Science and Technology 2014年第6期24卷 853-858页

作者： yuan yue Zhu Yongjian Wang Weijun yu weijian School of Energy and Safety Engineering Hunan University of Science and Technology Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines Hunan University of Science and Technology

In view of the buckling failure caused by large deformation of Mesozoic soft rock roadway in Shajihai mining area, such as serious roof fall, rib spalling, floor heave, etc., based on the detail site investigation,theoretical analysis, mineral composition test, microstructure test, water-physical property test and field experiments were carried out. And we revealed the compound failure mechanism of Mesozoic soft rock roadway in Shajihai mining area, namely the molecule expansion-shear slip of weak structural plane-construction disturbance. On this basis, the coupling support technology whose core is constant resistance with large deformation bolt was proposed. The feature of this supporting technology is that a new type of structural composite material was used, which makes the supporting system not only has the ideal deformation characteristics, but also has high supporting resistance. Thus the fully release of plastic energy within surrounding rock and reasonable control of the thickness of the plastic ring were realized. Then the differential deformation between the surrounding rock and support was eliminated by the secondary coupling support of bolt–mesh–cable, and the bolt with high strength was applied in the base angle to control floor. Eventually the collaborative bearing system of surrounding rock–support was formed. Through field tests the validity and rationality of support was also verified.

关键词： Mesozoic soft rock Failure mechanism Constant resistance with large deformationsupport Control measures Collaborative bearing

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Field investigations of high stress soft surrounding rocks and deformation control

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第4期7卷 421-433页

作者： weijian yu Weijun Wang Xinyuan Chen Shaohua Du Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines Hunan University of Science and Technology School of Energy and Safety Engineering Hunan University of Science and Technology

Field investigations of high stress soft rock deformations show that the high stress soft rock roadway can slide with large deformation. Severe extrusion and floor heave can also be subsequently observed. The supported roadway can be locally damaged or completely fail, where the floor has a large deformation and/or is seriously damaged. The factors inducing large deformation of surrounding rocks in deep roadway are rock strengths, structure face cutting types, stress states, stress release, support patterns, and construction methods. Based on the deformation characteristics of high stress soft rock roadway, a comprehensive support scheme is proposed. The overall support technology of＂step-by-step and joint, hierarchical reinforcement＂for roadway is presented, and the anchor cable and bolt parameters to check the design methods are also given. Finally, the proposed comprehensive support method＂bolt t metal mesh t U-steel arch t shortcrete t grouting and cable＂ is used in the extension section of east main haulage roadway at ？850 m level of Qujiang coal mine. The 173-day monitoring results show that the average convergence of sidewalls reaches 208 mm, and the average relative convergence of roof and floor reaches 448 mm, suggesting that this kind of support technology for controlling large deformation of high stress soft surrounding rock roadway is effective.

关键词： High stressSoft surrounding rocksRoadway deformationField investigationControl technology

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Cyclic-anion salt for high-voltage stable potassium-metal batteries

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National Science Review 2022年第10期9卷 177-187页

作者： Yanyao Hu Ling Fan Apparao M.Rao weijian yu Caixiang Zhuoma Yanhong Feng Zhihui Qin Jiang Zhou Bingan Lu School of Physics and Electronics Hunan University Department of Physics and Astronomy Clemson Nanomaterials Institute Clemson University School of Materials Science and Engineering Central South University

Electrolyte anions are critical for achieving high-voltage stable potassium-metal batteries(PMBs).However,the common anions cannot simultaneously prevent the formation of ’dead K’ and the corrosion of Al current collector,resulting in poor cycling ***,we demonstrate cyclic anion of hexafluoropropane-1,3-disulfonimide-based electrolytes that can mitigate the ’dead K’ and remarkably enhance the high-voltage stability of ***,even using low salt concentration(0.8 M) and additive-free carbonate-based electrolytes,the PMBs with a high-voltage polyanion cathode(4.4 V) also exhibit excellent cycling stability of 200 cycles with a good capacity retention of 83%.This noticeable electrochemical performance is due to the highly efficient passivation ability of the cyclic anions on both anode and cathode *** cyclic-anion-based electrolyte design strategy is also suitable for lithium and sodium-metal battery technologies.

关键词： cyclic anion low concentration additive-free electrolyte high-voltage potassium-metal batteries solid-electrolyte interface

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Research on characters of surrounding rock in complex geology conditions and supporting time

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Engineering Sciences 2008年第2期6卷 91-96页

作者： yu weijian Gao Qian Zhai Shuhua Zhang Meihua Civil and Environmental Engineering School University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of High-Efficient Mining and Safety of Metal Mines Beijing 100083 China

The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.

关键词： complex geological conditions surrounding rock characteristic test supporting time theological characteristic

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矸石充填整体置换“三下”煤柱引起的岩层移动与二次稳定理论

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岩石力学与工程学报 2011年第1期30卷 105-112页

作者：余伟健王卫军湖南科技大学煤矿安全开采技术湖南省重点实验室湖南湘潭411201 湖南科技大学能源与安全工程学院湖南湘潭411201

根据条带开采特点,针对矸石充填整体置换"三下"煤柱引起的二次岩层移动等问题,首先简述煤柱开采与矸石充填过程,并分析二次岩层移动机制及特征,认为二次岩层移动是由矸石充填支撑体和承重岩层的共同压缩引起的,上覆岩层形成的弯曲带层... 详细信息

根据条带开采特点,针对矸石充填整体置换"三下"煤柱引起的二次岩层移动等问题,首先简述煤柱开采与矸石充填过程,并分析二次岩层移动机制及特征,认为二次岩层移动是由矸石充填支撑体和承重岩层的共同压缩引起的,上覆岩层形成的弯曲带层面为波浪型下沉曲层;然后,根据充填支撑体的实际受力大小和极限强度,采用弹塑性力学及相关理论,推导"承重岩层+矸石充填体"承载体的二次稳定条件、安全系数、极限状态下的软化区宽度以及承载核区宽度的解析式,并给出矸石充填体压缩量w1和上覆承重岩层二次压缩量w2的计算公式,提出二次岩层移动下沉总量计算方法。宝源煤矿的实例计算表明"承重岩层+矸石充填体"承载体的安全系数Fs=1.36,处于稳定状态;"承重岩层+矸石充填体"承载体总压缩量w=0.833 m,矸石支撑体抵抗着较高的应力,维护着上覆岩层结构的二次稳定;数值分析表明,采空区上方应力得到充分释放,充填支撑体上方垂直应力呈马鞍形分布,承重岩层最大下沉位移平均值为0.801 m左右,接近理论计算值。

关键词：采矿工程条带开采矸石充填 “三下”煤柱岩层移动二次稳定

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深部软弱围岩叠加拱承载体强度理论及应用研究

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岩石力学与工程学报 2010年第10期29卷 2134-2142页

作者：余伟健高谦朱川曲湖南科技大学煤矿安全开采技术湖南省重点实验室湖南湘潭411201 湖南科技大学能源与安全工程学院湖南湘潭411201 北京科技大学土木与环境工程学院北京100083

目前,长锚索与锚喷网支护相结合的支护方式在深部软弱围岩中已经得到了广泛应用,但是对于这种联合支护结构的承载特点缺乏深入了解,特别是对于初次支护和二次支护的承载能力没有量化解析式。因此,在岩石力学理论的基础上,针对深部软弱... 详细信息

目前,长锚索与锚喷网支护相结合的支护方式在深部软弱围岩中已经得到了广泛应用,但是对于这种联合支护结构的承载特点缺乏深入了解,特别是对于初次支护和二次支护的承载能力没有量化解析式。因此,在岩石力学理论的基础上,针对深部软弱围岩的"锚喷网+锚索"联合支护特点,提出由主压缩拱(锚杆支护)和次压缩拱(密集型锚索支护)共同构成的叠加拱承载体力学模型;根据弹塑性理论、锚杆的中性点理论和锚索的力传递机制推导初次支护和适当让压后二次支护的承载体强度方程;并将"围岩-支护结构"组成的共同体看作一种等效耦合围岩,运用弹塑性力学方法得到这种等效耦合围岩的力学参数随释放位移(让压位移)变化的关系式。工程计算表明,金川III矿区破碎硐室经叠加拱支护后,极限承载能力q′max可达到513.34kN,等效耦合岩体?e值可达到47.54°,ce最大值为1.37MPa,提高围岩的峰后强度,有利于硐室围岩的长期稳定;现场监测也表明,进行叠加拱承载体支护后的硐室围岩变形趋于平稳,收敛速率小于0.1mm/d。

关键词：岩石力学深部围岩等效耦合围岩叠加拱承载体强度理论

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基于松软围岩变形特征的强化预支护技术研究

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矿业研究与开发 2006年第5期26卷 19-21,54页

作者：余伟健北京科技大学金属矿山高效开采教育部重点实验室北京100083

为解决松软围岩巷道的极不稳定性及寻求新的控制方法,在分析松软围岩变形特征的基础上,提出了强化预支护技术方法,并结合实际工程,获取一些岩性参数,用FLAC进行了4种预支护方案数值模拟和对比分析,认为强化预支护具有最优的特点。

关键词：松软围岩变形特征强化预支护技术数值模拟

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FDI、劳动力要素禀赋与环境污染——基于中国省际面板数据的实证研究

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投资研究 2020年第3期39卷 4-19页

作者：周晨余威健广州大学经济与统计学院

本文运用中国2000-2015年省际面板数据,通过构建环境污染综合指数,考察了FDI和劳动力要素禀赋的环境污染效应。结果表明,FDI对环境污染的影响并不显著,而劳动力要素禀赋会导致环境污染综合指数显著提高,环境质量随着时间的推移逐渐得到... 详细信息

本文运用中国2000-2015年省际面板数据,通过构建环境污染综合指数,考察了FDI和劳动力要素禀赋的环境污染效应。结果表明,FDI对环境污染的影响并不显著,而劳动力要素禀赋会导致环境污染综合指数显著提高,环境质量随着时间的推移逐渐得到改善。交互效应表明FDI与劳动力要素的共同作用会加剧环境污染,FDI有利于劳动偏向性技术进步,而不是生产技术"清洁化"。进一步的区域异质性模型证实了劳动力要素禀赋优势会使中西部地区沦为"污染天堂"。

关键词：外商直接投资劳动力要素禀赋环境污染交互效应

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