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Using a modified direct shear apparatus to explore gap and size effects on shear resistance of coarse-grained soil

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Particuology 2015年第6期13卷 82-89页

作者： Wenxi Fu Xing Zheng Xiaozhang Lei Jianhui Deng State Key Laboratory of Hydraulic and Mountain River Engineering Sichuan University Chengdu 610065 China Civil Engineering Hydrochina Guiyang Engineering Corporation LTD Guiyang 550081 China

This work used a modified direct shear apparatus, created newly by the authors, to explore effects of the gap between shear box halves and specimen size on the shear resistance of coarse-grained soil. The shear boxes of this apparatus were assembled from a series of steel structures capable of superimposition and nesting. Such characteristics facilitated variation of specimen size in both diameter and height. The new device can also maintain a constant gap during shearing. We performed a series of gap-effect and size-effect tests for two uniformly graded, coarse^grained soil samples. The test results showed that both the gap space and specimen size bad significant influences on shear resistance of the coarse-grained soil. Further, analysis of variations in shear strength indices led to a reasonable gap dimension and specimen size of the two soil samples.

关键词： Direct shear apparatus Gap effectSize effect shear resistance Coarse-grained soil

ROUGHNESS-INDUCED shear resistance OF MODE Ⅱ CRACK GROWTH

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Acta Metallurgica Sinica(English Letters) 1993年第6期6卷 397-404页

作者： ZHENG Yesha WANG Zhongguang AI Suhua State Key Laboratory of Fatigue and Fracture for Materials,Institute of Metal Research,Academia Sinica,Shenyang,China postdoctor,Shanghai Institute of Ceramics,Academia Sinica,Shanghai 200050,China

It is obtained in this paper that the fatigue threshold value of mode H was 1.9 times of that of mode Ⅰ in dual-phase steel(DPS),and the normal stress intensity factor range oJ mode Ⅱ branch crack tip was 2.2 times of that of mode Ⅰ.Above results illustrate that the resistance of mode Ⅱ crack growth was higher than that of mode Ⅰ,the former resulting from roughness-induced shear resistance,the latter,crack closure. The mode Ⅱ component can play two important roles in near-threshold fatigue crack growth:(1)increasing crack tip plasticity which accelerates the crack growth and(2)intro- ducing crack surface contact and rubbing to reduce the crack propagation *** means of crack closure,the quantity of shear resistance was easily solved in this *** friction shear stress strength factor range of mode Ⅱ,K_,is still much higher than the closure stress strength factor range of mode Ⅰ,K_(Ⅰ,cl).This illustrated that the roughness enlarged the second role and played a role of shielding crack tip from mode Ⅱ crack.

关键词： mixed-mode(Ⅰ/Ⅱ)fatigue crack growth threshold crack closure toughness shear resistance steel 16 Mn

Alleviation of the plastic deformation of gel ink under strong stress through an esterification of xanthan gum reinforcing its double helix structure

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Chinese Journal of Chemical Engineering 2024年第3期67卷 49-57页

作者： Xiaokun Li Mingyi Wang Zilu Liu Song Yang Na Xu Wei Zhao Gan Luo Shoujun Liu College of Chemical Engineering and Technology Taiyuan University of TechnologyTaiyuan 030024China Shanxi Engineering Center of Civil Clean Fuel Taiyuan University of TechnologyTaiyuan 030024China Shanxi Coking Coal in Yuncheng Salt Refco Group Ltd. Yuncheng 044000China

As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ***,as the double-helix structure connected by hydrogen bonds cannot resist the mechanical environment of strong stress,XG shows poor shear *** this study,a polymer gel with interpenetrating polymer network structure was prepared by esterifying XG,taking polystyrene maleic anhydride(SMA)as the *** addition to retaining the excellent rheological properties of XG,the generated polymer gel also exhibited high shear *** optimal addition amount of the esterification reaction modifier was determined as mXG:mSMA=5:3 according to the gel ink *** this amount,the viscosity of the modified xanthan gum(SXG)gel increased to 1578.8 mPa·s and 100.7 mPa·s at shear rates of 4 s1 and 383 s1,respectively,and the shear resistance increased more than 2 times compared to the unmodified *** is because of the ester bond formed by esterification that the reaction strengthens the interaction between molecular segments,enabling the new gel to resist to strong mechanical *** new polymer gel studied in this paper and the proposed mechanism of action provide new insights for the development of high-end gel ink and also provide theoretical support for the study of rheological properties of non-Newtonian fluids.

关键词： Gel ink Xanthan gum Esterification Simulation shear resistance Gels

A combined experimental and DEM investigation of grain interlocking in sheared granular assemblies

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Particuology 2024年第7期90卷 436-451页

作者： Rui Lu Qiang Luo Tengfei Wang David P.Connolly Tao Xie School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-Speed Railway Engineering(Southwest Jiaotong University) Ministry of EducationChengdu 610031China School of Civil Engineering University of LeedsLeeds LS29JTUK Department of Civil Engineering McMaster UniversityHamiltonONCanada

Compacted granular material,integral to geotechnical engineering,undergoes translation,rotation,and interlocking when subject to shear displacements or external *** present study focuses on the interlocking of heterogeneous granular materials,a complex behavior influenced by gradation,compaction,and varying particle geometry,and has consequently received limited attention in existing *** address this research gap,we conducted an analysis on the effect of grain interlocking on the shear resistance of granular assemblies,using a combination of laboratory testing and the discrete element method(DEM).Initially,large-scale direct shear tests were conducted on gravel−sand mixes with varying degrees of compaction and normal *** of the mixes also underwent subsequent shear reversal to explore the differences in grain interlocking between the two shearing processes on the shear *** analyzing the laboratory results,a mesoscopic scale investigation was performed by replicating the test using discrete element *** facilitate this,granular particle geometries were measured using 3D laser scanning based on the physical lab ***,based on these scans,discrete element R-block and ball models were utilized to construct both the coarse and fine particles within the *** vibro-compaction was employed to regulate the degree of *** results indicate that an increase in vertical pressure,coupled with a zero dilatancy angle,results in a rising stress ratio,indicative of grain *** interlocking exhibits a positive correlation with both the coarse content and the degree of compaction,and varies depending on the shear *** interlocking progresses,the shear band,induced by particle movement,expands and is associated with reduced particle rotation near the shear *** study further reveals a consistent positive correlation between interlocking and the principal orientation angle of strong normal c

关键词： Granular material Interlocking shear resistance Direct shear Discrete element method Vibro-compaction

Experimental study on the compression-shear performance of a new-type circumferential joint of shield tunnel

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Underground Space 2024年第1期14卷 138-155页

作者： Ziyang Zhou Kun Feng Yiteng Liu Bohan Wu Chunfang Lu Gang Lin Chuan He Key Laboratory of Transportation Tunnel Engineering of Ministry of Education Southwest Jiaotong UniversityChengdu 610031China China Academy of Railway Sciences Corporation Limited Beijing 100081China China Railway Eryuan Engineering Group Co. Ltd.Chengdu 610031China

To investigate the compression-shear behavior of a new circumferential joint based on the sleeve-straight bolt combination type connection of large-diameter shield tunnels,a series of full-scale joint experiments was carried *** the process of the experiment,more attention was paid to the specimen displacement,bolt stress and joint damage *** the basis of these experiment phenomena,this study discussed the compression-shear bearing process of the new connector,analyzed the damage mode of the joint structure,and finally evaluated the performance of the new *** is found that the bearing process of the joint can be divided into four stages:the transitional stage for overcoming the friction of the concrete,the sleeve bearing stage for the sleeve bearing shear loads alone,the combined bearing stage for bearing shear loads by the connector system,and the structural damage stage for structural instability and *** speaking,affected by connector position and hand hole,the positive compression-shear stiffness of the joint is less than the negative compression-shear stiffness,and the positive shear strength of the joint is greater than the negative shear *** increase of longitudinal axial force will improve the compression-shear performance of the *** relationship between longitudinal axial force and joint stiffness is a logarithmic *** use of new type of connector can effectively improve the compression-shear stiffness of joints under low shear loads,but the application of straight bolts will lose part of the strength performance.

关键词： Shield tunnel New type of connector shear resistance Full-scale experiment Circumferential joint

Strength and deformation behavior of the Yellow River silt under triaxial drained condition considering characteristic states

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Journal of Mountain Science 2023年第1期20卷 273-284页

作者： CHEN Yu-yuan WANG Yu-ke Hemanta HAZARIKA WAN Yong-shuai Department of Civil&Structural Engineering Kyushu UniversityFukuoka819-0385Japan College of Water Conservancy Engineering Zhengzhou UniversityZhengzhou450001China Graduate School of Engineering Kyushu UniversityFukuoka819-0385Japan

Currently,the application of the Yellow River silt in subgrade,especially in expressway subgrade,has not been widely *** main reason is that the research on the mechanical characteristics of the Yellow River silt used for subgrade filling is extremely *** this study,the static shear test of the Yellow River silt under drained condition was carried out using Global Digital Systems(GDS)triaxial apparatus,and the effects of confining pressure,relative density and shear rate on the strength and deformation behavior of the Yellow River silt were *** cohesive force of the Yellow River silt is low,and the friction angle is the main factor determining the shear *** angle at phase transformation stateφpt,friction angle at peak stateφps,friction angle at critical stateφcs,were obtained via the observation on the evolution law of mobilized friction angle during the whole shearing *** friction angles corresponding to three different characteristic states have the following magnitude relationship,namelyφps>φcs>φ*** strength parameters for low-grade subgrade and highgrade subgrade were chosen to be 29.33°and 33.75°.The critical state line(CSL),envelop of phase transformation(EOP),and envelop of dilatancy(EOD)for three different characteristic states were *** critical stress ratio M,the phase transformation stress ratio Mptand the dilatancy stress ratio Mdof the Yellow River silt are 1.199,1.235,1.152,*** results provide a basis for the mechanical analysis of the Yellow River silt subgrades and the subsequent establishment of dynamic constitutive model of the Yellow River silt.

关键词： Yellow River silt Stress-strain relationship shear resistance Friction angle

Experimental Research on shear Behavior of Reinforced Concrete Composite Beams Under Uniformly Distributed Load

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China Ocean Engineering 1998年第4期13卷 467-476页

作者： ZHAO Shunbo Ass. Prof., North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450045, P. R. China. N. China Inst. Water Conserv./H.P. Zhengzhou 450045 China

An experimental program was carried out to study the shear behavior of the reinforced concrete composite beam (RCCB) subjected to two-phase uniformly distributed load. A total of 12 reinforced concrete composite beams were tested: 10 of them were the RCCB subjected to two-phase uniformly distributed load, the other 2 were the comparative reinforced concrete beams cast at the same time as the RCCB subjected to one-phase uniformly distributed load. The interface of precast unit and recast concrete was natural and rough. The test range of the main composite factors: the ratio of precast section depth to composite section depth was from 0.35 to 0.65, the ratio of first-phase load moment to precast section ultimate bearing moment was from 0.25 to 0.65. Based on the test results, the stresses of the longitudinal reinforcements and stirrups, the load-bearing properties of the interface, the crack state and the failure characteristics of the RCCB under uniformly distributed load are discussed. The effects of the stirrups, the concrete strength and the composite factors on the shear resistance of the RCCB are analyzed, and the method for evaluating the shear resistance of the RCCB is proposed.

关键词： reinforced concrete composite beam shear resistance composite factor mechanism of failure

Synthesis and Performance of an Associative Anti-shear Drag Reducer Based on Hydrogen Bond Association of Dodecyl Methacrylate

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China Petroleum Processing & Petrochemical Technology 2023年第1期25卷 23-33页

作者： Lu Yong Li Chenhao Li Hao Chen Yue Xu Dan Wang Yiran Meng Yeqiao Zhang Xiaolai School of Chemistry and Chemical Engineering Shandong UniversityJinan 250061China PipeChina Eastern China Crude Oil Storage and Transportation Co. Ltd.Science and Technology R&D CenterXuzhou 221008China Shandong Dongyue Polymer Material Co. Ltd.Zibo 256401China State Key Lab of Fluorinated Functional Membrane Materials Zibo 256401China

Using K2S2O8-Na2SO3 as the redox initiation system,a hydrogen-bond-association-based dodecyl methacrylate system associative anti-shear drag reducer was synthesised by standard emulsion *** reaction process was simple and gentle as well as safe and *** design was carried out using molecular dynamics simulation *** results of infrared spectroscopy,thermogravimetric analysis,differential scanning calorimetry,gel chromatography,and laser light scattering showed that the reaction polymerisation was relatively complete,the product was uniform,the molecular weight distribution was controllable,and the synthesised polymer had good *** donor lauryl methacrylate-styrene-methacrylic acid(LMA-St-MAA)and acceptor lauryl methacrylate-styrene-dimethylaminoethyl methacrylate(LMA-St-DMA)polymers had an associative intermolecular interaction force,which increased the molecular cluster size of the associative system *** complex had good shear resistance,and the test results of the tube pump shear test showed that the synthesised associative oil-soluble polymer drag reduction system exhibited better drag reduction rate performance than poly-α-olefins over repeated *** research results provide a reference plan for minimising the number of station-to-station inputs,thereby ensuring the stability of oil pipelines and reducing transportation costs.

关键词： drag reducer associative effect drag reduction rate shear resistance

Mechanical strength of wheat grain varieties influenced by moisture content and loading rate

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International Journal of Agricultural and Biological Engineering 2018年第4期11卷 52-57页

作者： Yaoming Li Farman Ali Chandio Zheng Ma Imran Ali Lakhiar Abdul Razaque Sahito Fiaz Ahmad Irshad Ali Mari Umer Farooq Muhammad Suleman Jiangsu University School of Agricultural Equipment EngineeringZhenjiang 212013JiangsuChina Sindh Agriculture University Faculty of Agricultural EngineeringTandojamSindhPakistan Institute of Environmental Engineering and Management MUETJamshoroPakistan Department of Agricultural Engineering Bahaudin Zakaria UniversityMultanPakistan Department of Mathematics COMSATS UniversityIslamabadPakistan

Mechanical shear resistance of wheat grain is a significant concern for the designers and researchers related to the design of threshing,handling and processing machinery of the field *** grain mechanical properties directly affect the machine geometry and its operational *** present study was carried out to determine the shear resistance of five wheat varieties(Locally names;TD-02,Sindhu-1105,Benazir,China and SKD-118)influenced by moisture content(16.7%,18.7%and 19.5%)and loading rate(3 mm/s,6 mm/s and 9 mm/s).However,some physio-dimensional properties(length,width,thickness,slenderness ratio,surface area and sphericity)were obtained at different moisture *** results showed that the shear resistance reduced by increasing the moisture content and loading *** average shear resistance decreased from 10.45 N to 3.74 N for 3-9 mm/s loading rate at moisture content of 16.7%to 19.5%.Thus,the maximum correlation(r=0.905)of shear resistance obtained at 16.7%,whereas minimum correlation(r=0.692)obtained at 19.5%.The shear resistance of wheat grain was highly significant(pshear resistance decreased with an increase in the moisture content in the grain whereas deformation is increasing with the increase of moisture ***,the maximum bulk density of wheat grain obtained at 19.5%for SKD-118,while the minimum obtained at 16.7%for *** is recommended that the design and modification of wheat grain processing equipment should be executed on the physio-mechanical properties of grain varieties.

关键词： wheat grain shear resistance bulk density of grain varieties moisture content loading rates