检索结果-南通市图书馆

Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3221-3229页

作者： Juhyi Yim Yoonsung Lee Seungki Hong Ki-Bok Min R&D Center Hyundai Engineering and Construction75Yulgok-roJongno-guSeoulRepublic of Korea Department of Energy Systems Engineering and Research Institute of Energy and Resources Seoul National University1Gwanak-roGwanak-guSeoul08826Republic of Korea

To improve the accuracy of indirect tensile strength for a transversely isotropic rock in the brazilian test, this study considered the three-dimensional (3D) deformation and the nonlinear stress–strain relationship. A parametric study of a numerical brazilian test was performed for a general range of elastic constants, revealing that the 3D modeling evaluated the indirect tensile strength up to 40% higher than the plane stress modeling. For the actual Asan gneiss, the 3D model evaluated the indirect tensile strength up to 10% higher and slightly enhanced the accuracy of deformation estimation compared with the plane stress model. The nonlinearity in stress–strain curve of Asan gneiss under uniaxial compression was then considered, such that the evaluated indirect tensile strength was affected by up to 10% and its anisotropy agreed well with the physical intuition. The estimation of deformation was significantly enhanced. The further validation on the nonlinear model is expected as future research.

关键词： Anisotropy Transversely isotropy brazilian test Indirect tensile strength Nonlinearity 3D modeling

3-D distribution of tensile stress in rock specimens for the brazilian test

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2005年第6期12卷 495-499页

作者： Yong Yu Chunyan Meng Department of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China Department of Computing Science University of Alberta Edmonton T6G 2C5 Canada

It is claimed that the formula used for calculating the tensile strength of a disk-shaped rock specimen in the brazilian test is not accurate, because the formula is based on the 2-dimensional elastic theory and only suitable for very long or very short cylinders. The Matlab software was used to obtain the 2-dimensional distribution of stress in the rock specimen for brazilian test. Then the 2-dimensional stress distribution in brazilian disk was analyzed by the Marc FEM software. It can be found that the results obtained by the two software packages can verify each other. Finally, the 3-dimensional elastic stress in the specimen was calculated. The results demonstrate that the distribution of stress on the cross section of the specimen is similar to that in 2-dimension. However, the value of the stress on the cross section varies along the thickness of the specimen and the stress is bigger when getting closer to the end of the specimen. For the specimen with a height-to-diameter ratio of 1 and a Poisson＇s ratio of 0.25, the tensile strength calculated with the classical 2-D formula is 23.3% smaller than the real strength. Therefore, the classical 2-D formula is too conservative.

关键词： brazilian test tensile strength FEM rock Marc Matlab

Behaviour of layered sandstone under brazilian test conditions:Layer orientation and shape effects

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2013年第5期5卷 366-377页

作者： Abbass Tavallali André Vervoort Department of Civil Engineering University of Leuven

The experimental study in this paper focuses on the effects of the layer orientation and sample shape on failure strength and fracture pattern of samples tested under brazilian test conditions(*** loading of cylindrical discs)for one particular layered sandstone which is from Modave in the south of *** variations of the strength in combination with the failure patterns are examined as a function of the inclination angle between the layer plane and the loading *** experimental,results clearly show that the induced fracture patterns are a combination of tensile and/or shear *** shape effect experiments the layer thickness and the number of layer boundaries are *** blocks of Modave sandstone are used to prepare *** layer thickness is different among the various blocks,but the layer thickness in each studied rock block can be considered to be constant;hence,the number of layer boundaries changes according to the sample diameter for samples of the same *** experimental study shows that the layer thickness plays a more important role than the number of layer boundaries per sample.

关键词： Layered sandstone brazilian test Fracture pattern Layer activation Shape effect

Behaviour of layered sandstone under brazilian test conditions:Layer orientation and shape effects

在线全文

学校读者我要写书评

暂无评论

Behaviour of layered sandstone under Brazilian test conditio...

Tensile strength and failure behavior of rock-mortar interfaces: Direct and indirect measurements

第13届全国岩石动力学学术会议

作者： Abbass Tavallali André Vervoort Department of Civil Engineering University of LeuvenKasteelpark Arenberg 403001 LeuvenBelgium

The experimental study in this paper focuses on the effects of the layer orientation and sample shape on failure strength and fracture pattern of samples tested under brazilian test conditions(*** loading of cylindrical discs) for one particular layered sandstone which is from Modave in the south of *** variations of the strength in combination with the failure patterns are examined as a function of the inclination angle between the layer plane and the loading *** experimental,results clearly show that the induced fracture patterns are a combination of tensile and/or shear *** shape effect experiments the layer thickness and the number of layer boundaries are *** blocks of Modave sandstone are used to prepare *** layer thickness is different among the various blocks,but the layer thickness in each studied rock block can be considered to be constant;hence,the number of layer boundaries changes according to the sample diameter for samples of the same *** experimental study shows that the layer thickness plays a more important role than the number of layer boundaries per sample.

关键词： Layered sandstone brazilian test Fracture pattern Layer activation Shape effect

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 41-55页

作者： Ghasem Shams Patrice Rivard Omid Moradian Civil Engineering and Building Engineering Department Universitéde SherbrookeSherbrookeQuébecCanada Department of Earth Sciences Swiss Federal Institute of Technology(ETH)ZurichSwitzerland Department of Civil and Environmental Engineering Colorado School of MinesGoldenCOUSA

The tensile strength at the rock-concrete interface is one of the crucial factors controlling the failure mechanisms of structures,such as concrete gravity *** the critical importance of the failure mechanism and tensile strength of rock-concrete interfaces,understanding of these factors remains very *** study investigated the tensile strength and fracturing processes at rock-mortar interfaces subjected to direct and indirect tensile *** image correlation(DIC)and acoustic emission(AE)techniques were used to monitor the failure mechanisms of specimens subjected to direct tension and indirect loading(brazilian tests).The results indicated that the direct tensile strength of the rock-mortar specimens was lower than their indirect tensile strength,with a direct/indirect tensile strength ratio of 65%.DIC strain field data and moment tensor inversions(MTI)of AE events indicated that a significant number of shear microcracks occurred in the specimens subjected to the brazilian *** presence of these shear microcracks,which require more energy to break,resulted in a higher tensile strength during the brazilian *** contrast,microcracks were predominantly tensile in specimens subjected to direct tension,leading to a lower tensile *** monitoring of the cracking processes in the rock-mortar interfaces revealed that they show AE precursors before failure under the brazilian test,whereas they show a minimal number of AE events before failure under direct *** to different microcracking mechanisms,specimens tested under brazilian tests showed lower roughness with flatter fracture surfaces than those tested under direct tension with jagged and rough fracture *** results of this study shed light on better understanding the micromechanics of damage in the rock-concrete interfaces for a safer design of engineering structures.

关键词： Rock-mortar Rock-concrete Moment tensor inversion(MTI) Acoustic emission(AE) Digital image correlation(DIC) Tensile strength Direct tensile test brazilian test

Microscopic damage evolution of anisotropic rocks under indirect tensile conditions: Insights from acoustic emission and digital image correlation techniques

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1680-1691页

作者： Chaoqun Chu Shunchuan Wu Chaojun Zhang Yongle Zhang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Department of Civil&Mineral Engineering University of TorontoToronto ON M5S 1A4Canada Faculty of Land Resources Engineering Kunming University of Science and TechnologyKunmiing 650093China China Railway Sixth Group Limited Company Beijing 100036China

The anisotropy induced by rock bedding structures is usually manifested in the mechanical behaviors and failure modes of *** tests are conducted for seven groups of shale specimens featuring different bedding angles. Acoustic emission (AE) and digital image correlation (DIC) technologies are used to monitor the in-situ failure of the specimens. Furthermore, the crack morphology of damaged samples is observed through scanning electron microscopy (SEM). Results reveal the structural dependence on the tensile mechanical behavior of shales. The shale disk exhibits compression in the early stage of the experiment with varying locations and durations. The location of the compression area moves downward and gradually disappears when the bedding angle increases. The macroscopic failure is well characterized by AE event location results, and the dominant frequency distribution is related to the bedding angle. The b-value is found to be *** crack turning angle between layers and the number of cracks crossing the bedding both increase with the bedding angle, indicating competition between crack propagations. SEM results revealed that the failure modes of the samples can be classified into three types:tensile failure along beddings with shear failure of the matrix, ladder shear failure along beddings with tensile failure of the matrix, and shear failure along multiple beddings with tensile failure of the matrix.

关键词： anisotropic rock failure mechanism acoustic emission digital image correlation brazilian test

Analysis of stresses at the center of transversely isotropic brazilian disk

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第3期15卷 618-629页

作者： Ali Aminzadeh Florian Amann Institute of Geology of the Czech Academy of Sciences PragueCzech Republic Chair of Engineering Geology RWTH Aachen UniversityAachenGermany

This article presents the stresses at the center of a brazilian disk(BD)for transversely isotropic *** is shown that the solution of stresses at the center of an anisotropic disk is a function of the disk radius and the magnitude of applied load,as well as the material orientation with respect to the load axis and two dimensionless ratios with specific physical meanings and *** two dimensionless parameters are the ratios of Young’s modulus and apparent shear modulus,although the ratio of apparent shear modulus will be eliminated if the Saint-Venant assumption is *** finite element simulations are carried out to find the stresses at the disk center concerning the material orientation and the two dimensionless ***,an approximate formula obtained from analytical results,previously proposed in the literature for solving the tensile and compressive stresses at the disk center,is re-written and simplified based on these new *** results of the approximate formula fitted to the analytical results are compared to those obtained from numerical solutions,suggesting a good agreement between the numerical and analytical *** approximate equation for the shear stress at the disk center is also formulated based on the numerical ***,the influence of the assumptions for simplification of the proposed formula for the tensile,compressive,and shear stresses at the disk center is discussed,and simple and practical equations are proposed as estimations for the stresses at the center of the BD specimen for low to moderate anisotropic *** highly anisotropic rocks,the reference plots can be used for more accuracy.

关键词： brazilian test Transverse isotropy Rock anisotropy Anisotropic disk Tensile stress Shear stress

Deformation and Failure of Polymer Bonded Explosives

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Beijing Institute of Technology 2004年第1期13卷 43-47页

作者：陈鹏万黄风雷丁雁生 State Key Laboratory for the Prevention and Control of Explosion Disasters Beijing Institute of Technology Beijing 100081 China Institute of Mechanics Chinese Academy of Sciences Beijing100080 China

The deformation and failure of pressed polymer bonded explosives under different types of loads including tension, compression and low velocity impact are presented. brazilian test is used to study the tensile properties. The microstructure of polymer bonded explosives and its evolution are studied by use of scanning electronic microscopy and polarized light microscopy. Polishing techniques have been developed to prepare samples for microscopic examination. The failure mechanisms of polymer bonded explosives under different loads are analyzed. The results show that interfacial debonding is the predominant failure mode in quasi-static tension, while extensive crystal fractures are induced in compression. With the increase of strain rate, more crystal fractures occur. Low velocity impact also induces extensive crystal fractures.

关键词： polymer bonded explosives deformation failure microstructure brazilian test

Strength Developing in Clay-Andesite Brick

在线全文

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2016年第8期7卷 403-420页

作者： Víctor Julio García Alonso R. Zúñiga-Suárez Carmen Omaira Márquez Juan G. Pérez Francisco Fernández-Martínez Francisco Hernández-Olivares Universidad Nacional de Chimborazo Riobamba Ecuador Universidad Técnica Particular de Loja Loja Ecuador Universidad de Los Andes Mérida Venezuela Universidad Politécnica de Madrid Madrid Espana

The objective of this work was to develop a more and better understanding of the strength developing in clay-andesite fired brick. The purpose was to improve the quality of the clay bricks that are handmade in the southern region of Ecuador to make them suitable for more widespread use in the local construction industry. To achieve our goal, we first physically, chemically, and mechanically characterized the “clayey” and “sandy” materials used in the fabrication of handmade bricks in the region. Second, the optimal mixture (OM): the optimal proportion between the amounts of “clayey” and “sandy” material was sought. Third, clay bricks were prepared using the OM, baked at 950°C, and characterized. In addition, bricks produced by regional artisans were characterized, and the results were compared with the results obtained for the bricks prepared using the OM. Our data reveal that the optimal mixture is 50% “clayey” material and 50% “sandy” material and that with this mixture, an average improvement in brick quality of 300% can be achieved;thus, the use of the OM makes it possible to expand the use of these bricks in the local construction industry and enables an environmentally friendly production process by reducing the intensive exploitation of regional clay deposits. This improvement is achieved by virtue of the anorthite enrichment that occurs in the solid solution, which results from the evolution of andesine. The anorthite contributes to the formation of a stronger matrix among the different grains of the material. Conditions are favorable for this enrichment process to occur when “sandy” materials with high contents of andesite, which is common in Ecuadorian soils, are used.

关键词： Anorthite Andesine Andesite Component Fired Bricks brazilian test

EFFECTS OF INTERMEDIATE PRINCIPAL STRESS ON COMPRESSIVE AND TENSILE STRENGTHS OF SANDSTONES

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

EFFECTS OF INTERMEDIATE PRINCIPAL STRESS ON COMPRESSIVE AND ...