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Failure mechanism and control technology of water-immersed roadway in high-stress and soft rock in a deep mine

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International Journal of Mining Science and Technology 2017年第2期27卷 245-252页

作者： Yang Renshu Li Yongliang guo dongming Yao Lan Yang Tongmao Li Taotao School of Mechanics and Architecture Engineering China University of Mining and TechnologyBeijing 100083China State Key Laboratory for Geomechanics and Deep Underground Engineering Beijing 100083China Faculty of Resources and Safety Engineering China University of Mining and TechnologyBeijing 100083China

Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering background and employing field investigation, tests of rock structure, mechanical properties and mineral composition. The main factors leading to the surrounding rock failure include the high and complex stress state of the water sumps, high-clay content and water-weakened rock, and the unreasonable support design. In this paper, the broken and fractured rock mass near roadway opening is considered as ground small-structure, and deep stable rock mass as ground large-structure. A support technology focusing on cutting off the water, strengthening the small structure of the rock and transferring the large structure of the rock is proposed. The proposed support technology of interconnecting the large and small structures, based on high-strength bolts, high-stiffness shotcrete layer plugging water,strengthening the small structure with deep-hole grouting and shallow-hole grouting, highpretensioned cables tensioned twice to make the large and small structures bearing the pressure evenly,channel-steel and high-pretensioned cables are used to control floor heave. The numerical simulation and field test show that this support system can control the rock deformation of the water sumps and provide technical support to similar roadway support designs.

关键词： High stress and soft rock Water immersion Failure mechanism Large and small structures Rework control

Dynamic caustics test of blast load impact on neighboring different cross-section roadways

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International Journal of Mining Science and Technology 2016年第5期26卷 803-808页

作者： guo dongming Zhou Baowei Liu Kang Yang Renshu Yan Pengyang School of Mechanics and Architecture Engineering China University of Mining ＆ Technology Beijing 100083 China State Key Laboratory for Geomechnics ＆Deep Underground Engineering Beijing 100083 China

Using digital laser dynamic caustics experimental system and conducting simulation experiment researched the influence rule of blasting excavation of a new roadway on neighboring existed different cross-section roadways. The experimental results show that the influence of blast load on adjacent roadway has a good relationship with the cross-section of roadway. The expansion distance of precrack existed in circular, arch-wall, rectangular roadway is respectively 1.76, 1.61 and 0 cm under blast *** the same time, the direct-blast side of rectangular roadway has more obvious damage compared with circular and arch-wall roadway. It explains that plane reflects more stress wave than arc, so that it exerts more tensile failure in the direct-blast side, which leads to less stress wave diffracting to the precrack in the back-blast side. When the precrack extends, higher value dynamic stress intensity factor in circular roadway works longer than that of arch-wall roadway. Indirectly, it explains that plane's weakening function on stress wave is significantly stronger than arc. Stress wave brings about self-evident influence on the upper and bottom endpoints of the rectangular roadway, and it respectively extends 1.03, 2.06 cm along the line link direction of the center of the blasthole and the upper and bottom endpoints on the right wall.

关键词： Dynamic caustics Blast load Different cross-section roadways Precrack Dynamic stress intensity factor

高校在线开放课程教学改革的实践探索——以中国矿业大学(北京)为例

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大学教育 2024年第13期 42-45页

作者：庄海涛郭东明李礼中国矿业大学(北京)教务处北京100083

文章对当前高校在线开放课程的选用、考核与评价以及学分认定等方面存在的问题进行了分析,并以中国矿业大学(北京)为例,介绍了学校以教育数字化为支撑,从在线开放课程的审核机制、管理体系和学分认定模式三个方面着手开展的实践探索,以... 详细信息

文章对当前高校在线开放课程的选用、考核与评价以及学分认定等方面存在的问题进行了分析,并以中国矿业大学(北京)为例,介绍了学校以教育数字化为支撑,从在线开放课程的审核机制、管理体系和学分认定模式三个方面着手开展的实践探索,以期为高校在线开放课程教学改革提供有益参考。

关键词：在线开放课程教育数字化教学改革

Implementation strategies for high accuracy grinding of hydrodynamic seal ring with wavy face for reactor coolant pumps

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Science China(Technological Sciences) 2013年第10期56卷 2403-2412页

作者： FENG Guang guo dongming HUO FengWei JIN ZhuJi KANG RenKe Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education Dalian University of Technology

Large size mechanical seals are one of the most important components used in reactor coolant ***,the hydrodynamic seal rings with wavy face are difficult to machine due to their high hardness and high form accuracy *** order to solve this difficult problem,a novel four-axis linkage grinding method using a cup wheel to process the hydrodynamic seal rings by line contact was proposed.A preliminary study indicates that the form error of the ground seal ring surface is extremely sensitive to different linkage relations of the four *** taking the center height of the cup wheel and the laws of motion along the X-axis,Z-axis,B-axis and C-axis as control variables,their effects on the principle form error of the ground surface are *** implementation strategies are proposed to reach lower principle form *** is found that the minimal principle form error is only 9.64 nm and hence its influence on the ground seal ring shape can be neglected in designing an ultra-precision grinding *** addition,the results indicate that the position accuracy of the X-axis at the microscale is acceptable no matter which implementation strategy is *** study is expected to serve as a theoretical basis for design and development of the four-axis ultra-precision grinding machine.

关键词： reactor coolant pump hydrodynamic seal ring wavy face grinding cup wheel high accuracy

Special issue： Near-net shaping technology

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Frontiers of Mechanical Engineering 2018年第1期13卷 1-2页

作者： Dequn LI dongming guo Qingxue HUANG Yanchun LOU State Key Laboratory of Material Processing and Die & Mold Technology Huazhong University of Science and Technology Wuhan 430074 China Key Laboratory for Precision & Non-traditional Machining of Ministry of Education Dalian University of Technology Dalian 116024 China Heavy Machinery Engineering Research Center of Education Ministry Taiyuan University of Science and Technology Taiyuan 030024 China Shenyang Research Institute of Foundry Shenyang 110022 China

Near-net shaping is an efficient, economical and environmentally-friendly approach to manufacture products which are very close to the final shape, reducing the need for surface finishing. It has become more and more important to use raw materials and energy in an optimal way. Near-net shaping technology has attracted increasing attention in both academic and industrial communities, especially in China, because China has become the world＇s largest regional market for main material forming methods, such as casting, forging and injection molding. The main objective of this special issue in Frontiers of Mechanical Engineering is to bring together the leading ideas, experience and research results of academic scientists and researchers on various aspects of near-net shaping technology. This special issue contains eleven papers contributed by prestigious experts from different countries, including four reviews and seven research articles. These papers cover a broad area of the near-net shaping technology,

关键词： Injection molding casting-forging Material forming raw material Forged Energy sources Casting Surface finish

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber reinforced plastics

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Frontiers of Mechanical Engineering 2020年第4期15卷 538-546页

作者： guofeng MA Renke KANG Zhigang DONG Sen YIN Yan BAO dongming guo Key Laboratory for Precision and Non-Traditional Machining of Ministry of Education Dalian University of TechnologyDalian 116024China

Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

关键词： longitudinal–torsional coupled ultrasonically drilling CFRP thrust force hole quality

Smoothed-Particle Hydrodynamics Investigation on Brittle-Ductile Transition of Quartz Glass in Single-Grain Grinding Process

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Nanomanufacturing and Metrology 2020年第4期3卷 299-306页

作者： Xiaoguang guo Ming Li Xichun Luo Ruifeng Zhai Renke Kang Zhuji Jin dongming guo Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China Centre for Precision Manufacturing Department of DesignManufacture and Engineering ManagementUniversity of StrathclydeGlasgow G11XJUK

The smoothed-particle hydrodynamics(SPH)method was introduced to simulate the quartz glass grinding process with a single grain under micrp-nano *** investigate the mechanism of brittle-ductile transition,such factors as the machin-ing depth,grinding force,maximum equivalent stress,and residual stress were *** simulation results indicate that quartz glass can be machined in a ductile mode under a certain *** this paper,the occurrence and propaga-tion of cracks in quartz glass at different grinding depths(0.1-1μm)are observed,and the critical depth of brittle-ductile transformation is 0.36 *** different grinding depths,the grinding force ratio is greater than *** the cutting depth is 0.4 um,the crack propagation depth is about 1.2μm,which provides a basis for the prediction of subsurface damage *** addition,the correctness of the simulation result was verified by carrying out scratch experiments of varying cutting depth on optical quartz glass.

关键词： Quartz glass Brittle ductile transition Ultra precision grinding Smoothed particle hydrodynamics

Experimental Study on Dynamic Mechanical Properties of Sprayed Concrete-Surrounding Rock Combined Body

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Journal of Beijing Institute of Technology 2019年第2期28卷 278-285页

作者： dongming guo Pengyang Yan Longfei Fan Yingshi Zhang Xiaoye Wang School of Mechanics and Civil Engineering China University of Mining&Technology(Beijing)Beijing 100083China State Key Laboratory for Geomechanics and Deep Underground Engineering Beijing 100083China

To investigate the dynamic response problem of the double medium formed by the adherence of sprayed concrete and surrounding rock in the tunnel,a split Hopkinson pressure bar of 75 mm in diameter was adopted at the ages of 3,7 and 10 *** results showed that dynamic compressive strength and dynamic increase factors(DIF)of the combined bodies increase with the strain *** the growth of strain rate,the critical strain of the combined bodies first increases,then ***,the combined bodies of 3 d reveal the plastic property and brittle property for 7 d and 10 d when the strain rate is over 80/*** failure characteristic of the sprayed concrete changes from tearing strain damage to crushing damage as the growth of strain rate,and the failure characteristic of rock presents the tensile failure mode as demonstrated by the scanning electron microscope(SEM).

关键词： sprayed concrete-surrounding rock combined body dynamic compressive strength dynamic increase factors critical strain failure modes

Dynamic characteristics of an intestine capsule robot with variable diameter

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Chinese Science Bulletin 2010年第17期55卷 1813-1821页

作者： ZHANG YongShun JIANG ShengYuan ZHANG XueWen YU HongHai WANG DianLong guo dongming Key Laboratory for Precision & Non-traditional Machining of Ministry of Education of China Dalian University of Technology Dalian 116023 China Mechanical Engineering School Beihua University Jilin 132021 China

This paper proposes an intestine capsule robot with variable diameter. It is driven by external rotating magnetic field and has the function of automatic radial clearance compensation. An external magnetic field generating device and a capsule robot with variable diameter are developed. Radial dynamic balance equation and kinematics equation of the capsule robot traveling inside flexible elasto-wall environment are established, and dynamic characteristics of the capsule robot inside flexible elasto-wall pipe and rigid wall pipe environments are analyzed and compared. Simulations and experiment results show that its dynamic characteristics in both pipes are almost the same. Under the action of radial clearance compensation, fluid dynamic pressure around outer surface of the capsule robot and its propulsion, as well as its adaptability to diameter change range, are significantly improved. Its propulsion and moving speed are controlled by adjusting rotating angular speed of the rotating magnetic field. This innovative capsule robot with radial clearance compensation has a promising prospect for inside intricate gastrointestinal (GI) tract in non-invasive therapy applications.

关键词：动态特性机器人变直径胶囊胃肠动力平衡方程径向间隙旋转磁场