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International Journal of Mining Science and Technology 2018年第5期28卷 807-811页

作者： Faham Tahmasebinia Chengguo Zhang Ismet Canbulat Onur Vardar Serkan Saydam School of Minerals and Energy Resources Engineering University of New South Wales

Designing reliable yielding support system to mitigate the effect of the kinetic energy in burst-prone conditions in mining and tunneling excavations is one of the challenges for geotechnical engineers. A combination of the support elements can be used to increase rock strength and minimise the displacement of unstable rock mass. It is important to understand how the support system works to ensure the stability of underground excavations. Cable bolts have been commonly used as an effective underground support system and an element of reinforcement to improve rock stability. Cable bolts are usually considered to be subjected to static loads under relatively low stress environments, however, in burst-prone conditions, they might be subjected to dynamic loads. Cable bolts as well as other support elements are used in burst-prone conditions to absorb the kinetic energy of the removed rock to avoid sudden and violent failures. This paper develops numerical and a novel analytical simulation technique for cable bolts to assess their structural behaviour under static and dynamic loading conditions. The numerical and analytical models are then validated against experimental observations reported in the literature, which demonstrates the reliability of the proposed models.

关键词： Cable bolts Yielding support Coal burst Shear dynamic loading

Mechanical properties and supporting effect of CRLD bolts under static pull test conditions

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International Journal of Minerals,Metallurgy and Materials 2017年第1期24卷 1-9页

作者： Xiao-ming Sun Yong Zhang Dong Wang Jun Yang Hui-chen Xu Man-chao He State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijingBeijing 100083China State Key Laboratory of Mining Disaster Prevention and Control Co-fotmded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266590China

A device for supporting soft rock masses combined with a constant resistance structure characterized by constant resistance and large deformation at the end of a steel bar, known as the constant resistance and large deformation（CRLD） bolt, has recently been developed to counteract soft rock swelling that often occurs during deep mining. In order to further study the mechanical properties of the CRLD bolt, we investigated its mechanical properties by comparison with the conventional strength bolt（rebar） using static pull tests on many aspects, including supporting capacity, elongation, radial deformation, and energy absorption. The tests verified that the mechanical defects of the rebar, which include the decrease of bolt diameter, reduction of supporting capacity, and emergence and evolution of fracture until failure during the whole pull process, were caused by the Poisson＇s ratio effect. Due to the special structure set on the CRLD bolt, the bolt presents a seemingly unusual phenomenon of the negative Poisson＇s ratio effect, i.e., the diameter of the constant resistance structure increases while under-pulling. It is the very effect that ensures the extraordinary mechanical properties, including high resistance, large elongation, and strong energy absorption. According to the comparison and analysis of numerical simulation and field test, we can conclude that the CRLD bolt works better than the rebar bolt.

关键词： deep mining bolts mechanical properties rock support static pull test

A study of the load transfer behavior of fully grouted rock bolts with analytical modelling

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International Journal of Mining Science and Technology 2020年第1期30卷 105-109页

作者： Jianhang Chen Fulian He Shoubao Zhang School of Energy and Mining Engineering China University of Mining&TechnologyBeijing 100083China Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources China University of Mining&TechnologyBeijing 100083China

Fully grouted rock bolts have been used in mining industry for many years.Much research has been conducted to evaluate the load transfer behavior of fully grouted rock bolts with experimental programs.However,compared with that,less work has been conducted with analytical modelling.Therefore,in this paper,the authors used an analytical model to study the load transfer behavior of fully grouted rock bolts.To confirm the credibility of this analytical model,an in-situ pull-out test was used to validate this model.There was a close match between the experimental result and the analytical result.Following it,a parametric study was conducted with this analytical model.The influence of coefficients,Young’s modulus of the rock bolt and the diameter of the rock bolt on the load transfer performance of rock bolts was studied.Furthermore,the load distribution along the fully grouted rock bolt was analytically studied.The results show that the axial load in the rock bolt decayed from the loaded end to the free end independent of the pull-out load.However,the trend of the load distribution curve was influenced by the pull-out load.This paper was beneficial for better understanding the load transfer mechanism of fully grouted rock bolts.

关键词： Rock bolts Load transfer Analytical modelling Parametric study Bond-slip model

Fundamental principles of an effective reinforcing roof bolting strategy in horizontally layered roof strata and areas of potential improvement

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International Journal of Mining Science and Technology 2018年第1期28卷 67-77页

作者： Russell Frith Guy Reed Martin McKinnon Mine Advice Pty Ltd New South Wales 2282Australia

It is arguable that the development of reinforcing roof bolting systems has largely stagnated in recent times, primarily due to the prevailing industry view that few, if any, further improvements can be made to what currently exists.However, this paper contends that reinforcing roof bolting systems can be further refined by considering both the specific manner by which horizontally bedded roof strata loses its natural self-supporting ability and the specific means by which reinforcing roof bolts act to promote or retain this natural self-supporting ability.The Australian coal industry has insisted on minimising bolt-hole diameter to maximise load transfer and on targeting full-encapsulation by any means necessary for many years.This has led to a significant, albeit unintended, consequence in terms of overall roof bolting effectiveness, namely increased resin pressures during bolt installation and the associated potential for opening bedding planes that may have, otherwise, remained closed during the bolt installation process.Given that the natural self-supporting ability of roof strata is strongly linked to whether bedding planes are open or closed, logically, minimising resin pressures should be a significant benefit.This paper focuses primarily on three key issues that relate directly to the function of the roof bolting system itself:(1) the importance of proper resin mixing in the context of maximising load transfer strength and stiffness,(2) the importance of minimising resin pressures developed during bolt installation, and(3) the importance of maximising the effectiveness of the available bolt pre-tension.All mine operators should be invested in improving the individual effectiveness of each installed roof bolt, even by relatively small incremental amounts, so this is an important topic for discussion within the mining community.

关键词： Roof bolts Strata reinforcement Partial-encapsulation Pre-tension Resin mixing Improved bolt effectiveness

Prying Force Calculation and Design Method for T-shaped Tensile Connector with High Strength Bolt

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Journal of Harbin Institute of Technology(New Series) 2015年第2期22卷 103-107页

作者： Zhaoxin Hou Guohong Huang Chao Gong College of Civil Engineering Tongji University Central Research Institute of Building and Construction MCC GroupCo.Ltd. National Engineering Research Center for Steel Construction

In order to establish the design method for T-shaped tensile connector with high strength bolt,the theoretical analysis is carried out. Firstly,it analyzes the performance of the connector and establishes prying force calculation model. Based on the model,prying force equation and function between bolt prying force and flange thickness is derived,and the min and max thickness requirement of flange plate under a certain tension load is then obtained. Finally,two simplified design methods of the connector are proposed,which are bolt pulling capacity method and flange plate bending capacity method.

关键词： prying force T-type joints high strength bolts flange thickness

Characterization of Strength-Shift Behavior of bolts Connected with and without Preloading

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Journal of Mechanics Engineering and Automation 2018年第1期8卷 9-16页

作者： A.Trindade Departamento de Engenharia Mecanica e Gestao Industrial Instituto Politecnico de ViseuPortugal

Bolted joins allow for more efficient joining of parts(mechanical and structural components)when assembly and disassembly,called interchangeability,are concerned.Also and for this reason,they are the most widely used in the final assembly,already in construction,in a state of final consolidation of the structure.This work began in a pedagogical action to compare the experimental results with those obtained by Eurocode 3(EN 1993-1-8)in simple joints with screws subject to cutting,the study evolved the analysis of the behavior of the screws themselves in the joint.Tests were carried out with great dimensional accuracy,for new bolted connections,with different bolt’s number,according to different arrangements and repeated in cases of simple and preloaded tightening.The experimental work,carried out on a uniaxial tensile testing machine,consisted in subjecting the connections to a growing effort so that the bolts,being subject to the cut,would break through the thread-free zone.The analysis of results and their comparison(in force—displacement diagrams)allow drawing conclusions regarding the true behavior of the bolted connections.The characterization of the thresholds of the initial zone of the force—displacement curves,in the cases of connections with preloading—was the objective of study.The transfer of forces and the influence of friction on the bonds without and with preloading were then characterized.The main objective of this project is to know the meaning of the calculated values in the preloaded and non-preloaded links by Eurocode 3.

关键词： bolts connections collapsible preloading Eurocode 3

Experimental Strain Investigation of Bolt Torque Effect in Mechanically Fastened Joints

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Engineering（科研） 2012年第7期4卷 359-367页

作者： Nashwan Younis Department of Engineering Indiana University Purdue University Fort Wayne USA

In this study, a different issue of mechanical engineering interests is determined for threaded fastened joints. A series of photoelastic experiments were performed to determine the maximum strains for the holes in a tensile flat plate subjected to bolt-nut loads. Pertinent strain distributions were examined to determine the roll of the torques on the bolts in mini mizing the strain;hence stress concentration. The experimental determination of maximum strains is needed as a way to validate future theoretical and numerical results, and provide a valuable aid to their application. The emphasis of this paper is on deformation. The results indicate that strains can decrease significantly with the increase of the bolt's pre-load.

关键词： Maximum Strains Fastened Joint bolts Torque Reflected Photoelasticity

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超级系统维护工具

新潮电子 1998年第6期 15-17页

作者：范相儒代凡