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Influence of anchorage length and pretension on the working resistance of rock bolt based on its tensile characteristics

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International Journal of Coal Science & Technology 2021年第6期8卷 1384-1399页

作者： Jucai Chang Kai He Dongdong Pang Dong Li Chuanming Li Bingjun Sun Key Laboratory of Safe and Effective Coal Mining of the Ministry of Education Anhui University of Science and TechnologyHuainan 232001China

In coal mining roadway support design,the working resistance of the rock bolt is the key factor affecting its maximum support *** improvement of the working resistance is of great significance to roadway *** on the rock bolt’s tensile characteristics and the mining roadway surrounding rock deformation,a mechanical model for calculating the working resistance of the rock bolt was established and *** the mining roadway of the 17102(3)working face at the Panji No.3 Coal Mine of China as a research site,with a quadrilateral section roadway,the influence of pretension and anchorage length on the working resistance of high-strength and ordinary rock bolts in the middle and corner of the roadway is *** results show that when the bolt is in the elastic stage,increasing the pretension and anchorage length can effectively improve the working *** the bolt is in the yield and strain-strengthening stages,increasing the pretension and anchorage length cannot effectively improve the working *** influence of pretension and anchorage length on the ordinary and high-strength bolts is *** ordinary bolt’s working resistance is approximately 25 kN less than that of the high-strength *** pretension and anchorage length are considered separately,the best pretensions of the high-strength bolt in the middle of the roadway side and the roadway corner are 41.55 and 104.26 kN,respectively,and the best anchorage lengths are 1.54 and 2.12 m,*** best anchorage length of the ordinary bolt is the same as that of the high-strength bolt,and the best pretension for the ordinary bolt in the middle of the roadway side and at the roadway corner is 33.51 and 85.12 kN,*** research results can provide a theoretical basis for supporting the design of quadrilateral mining roadways.

关键词： Working resistance of rock bolt pretension Anchorage length Ordinary bolt High-strength bolt Quadrilateral section roadway

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Axisymmetric wetting of a liquid droplet on a stretched elastic membrane

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Applied Mathematics and Mechanics(English Edition) 2023年第6期44卷 997-1006页

作者： C.Q.RU Department of Mechanical Engineering University of AlbertaEdmontonAB T6G 2G8Canada

Wetting of a liquid droplet on another liquid substrate is governed by the well-known Neumann *** present work aims to develop an explicit modified version of the Neumann equations for axisymmetric wetting of a liquid droplet on a highly stretched elastic membrane of non-zero bending *** explicit modified form of the Neumann equations is derived to determine the two contact angles,which is reduced to Young's equation for a liquid droplet on a rigid membrane or to the Neumann equations for a liquid droplet on another liquid *** implications of the modified Neumann equations are examined by comparison with some previous results reported in the recent literature,particularly considering the ranges of material and geometrical parameters of the liquid droplet-membrane system which have not been recently addressed in the literature.

关键词： Neumann equation Young's equation liquid droplet membrane pretension

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Mechanical behavior and failure mechanisms of rock bolts subjected to static-dynamic loads

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International Journal of Mining Science and Technology 2024年第3期34卷 281-288页

作者： Hongpu Kang Guiyang Yuan Linpo Si Fuqiang Gao Jinfu Lou Jinghe Yang Shuangyong Dong CCTEG Coal Mining Research InstituteBeijing 100013China State Key Laboratory of Intelligent Coal Mining and Strata Control Beijing 100013China

This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal *** a housemade load frame to simulate various failure scenarios,pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined *** experimental results denote that with increased impact energy,maximum and average impact loads on rock bolts escalate significantly under pretension,initiating plastic deformation beyond a certain *** minor reductions in the yield load due to impactinduced damage,pretension aids in constraining post-impact deformation rate and fluctuation degree of rock ***,impact-induced plastic deformation causes internal microstructure dislocation,fortifying the stiffness of the rock bolt support *** magnitude of this fortification is directly related to the plastic deformation induced by the *** findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation,emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency.

关键词： Rock bolt pretension Static and dynamic load Impact

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A Soft Robotic Fish with Variable-stiffness Decoupled Mechanisms

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Journal of Bionic Engineering 2018年第4期15卷 599-609页

作者： Kangkang Li Hongzhou Jiang Siyu Wang Jianmin Yu School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China

A Body and/or Caudal Fin （BCF） fish modulate its body stiffness by mechanisms consisting of antagonistic muscles. The mecha- nisms can be considered as Redundant Planar Rotational Parallel Mechanisms （RPRPM） with antagonistic flexible elements. For a typical RPRPM, its stiffness consists of the adjustable stiffness resulting from internal forces and the inherent stiffness caused by inherent com- pliances of flexible elements. In order to decouple the adjustable stiffness from the inherent stiffness and expand the range of stiffness variation, a variable-stiffness decoupled mechanism based on the Mechanically Adjustable Compliance and Controllable Equilibrium Position Actuator （MACCEPA） is presented and used to construct a soft robotic fish with large stiffness variation. According to the analysis of the evolution from RPRPM to MACCEPA, it can be found that MACCEPA is just a special type of RPRPM with only an adjustable stiffness. In addition, MACCEPA existed before RPRPM mechanism. The prototype of the soft robotic fish with variable- stiffness decoupled mechanisms is built to explore the relationships between the body stiffness and the swimming performance. It is validated experimentally that the stiffness variation multiple of the robotic fish is raised, the swimming performance of the robotic fish is improved when the stiffness is modulated to match the driving frequency.

关键词： bionic soft robotic fish variable stiffness decoupled MACCEPA pretension

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Deformation-softening behaviors of high-strength and high-toughness steels used for rock bolts

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1872-1884页

作者： Ding Wang Manchao He Zhigang Tao Aipeng Guo Xuchun Wang State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining&TechnologyBeijing100083China Research Institute for Deep Underground Science and Engineering China University of Mining&TechnologyBeijing100083China School of Civil Engineering Qingdao University of TechnologyQingdao266033China

In deep ground engineering,the use of high-strength and high-toughness steels for rock bolt can significantly improve its energy absorption ***,the mechanisms and effects of rock loading conditions on this kind of high energy-absorbing steel for rock bolt remain *** this study,taking Muzhailing highway tunnel as the background,physically based crystal plasticity simulations were performed to understand the effect of rock loading rate and pretension on the deformation behaviors of twinning induced plasticity(TWIP)steel used for rock *** material physical connecting to the underlying microscopic mechanisms of dislocation glide and deformation twinning were incorporated in numerical *** rock loading conditions were mimicked by the real-time field monitoring data of the NPR bolt/cable equipment installed on the tunnel surrounding rock *** results indicate that the bolt rod exhibits pronounced deformation-softening behavior with decrease of the loading *** is also a sound deformation-relaxation phenomenon induced by the dramatic decrease of loading rate after *** high pretension(>600 MPa or 224 k N)can help bolt rod steel resist deformation-softening behavior,especially at low loading rate(pretension was found to be the major parameter accounting for the deformation-relaxation *** results provide the theoretical basis and technical support for practical applications.

关键词： Rock bolt High-strength and high-toughness steels Loading rate pretension Deformation-softening Crystal plasticity

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Modal Experiments and Finite Element Analysis of the Bolted Structure Considering Interface Stiffness and Prtension

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International Journal of Plant Engineering and Management 2012年第2期17卷 87-94页

作者： WEI Li-dui DUAN Shu-lin WU Ji WU Qi-li XING Hui Marine Engineering College Dalian Maritime University Dalian 116026 P. R. China

It is particularly important to evaluate natural frequencies and natural modes of the structure of bolted joints to avoid the failures of the structure due to the resonance. The vibration characteristics of bolted structures are closely connected to surface roughness of contact interfaces, the magnitude of pretension of the bolts and the number of clamping bolts. In this paper, the effect of the factors above on the natural frequencies of bolted structures is sys- tematically investigated by experiments. Then, the finite element method is applied to analyze the effect. Finally, the numerical method is validated by experimental measurements of the natural frequencies.

关键词： surface roughness pretension natural frequency FEM bolted structures

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Pretensin Simulation of the Long Span Truss String Structures Supported by the Temporary Structures

Pretensin Simulation of the Long Span Truss String Structure...

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The 10th EPMESC

作者： R. Yu * Y. F. Luo Y. Huang College of Civil Engineering Tongji University Shanghai 200092 China

During the pretension of the truss string structure (TSS), the stiffness and integrity of structure are improved since the tension of the string. Before pretension, lots of falseworks are set up in or

关键词： truss string structure pretension falseworks simulate coaction

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