检索结果-南通市图书馆

boundary effect of toppling failure based on three-dimensional mechanical model

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2022年第11期19卷 3314-3322页

作者： CAI Jun-chao ZHENG Da JU Neng-pan HUANG Run-qiu ZHAO Wei-hua School of Civil Engineering Henan University of Science and TechnologyLuoyang 471023China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China

Previous researches on the mechanical model of toppling failure mainly concentrated on twodimensional mechanical model(TwDM) analysis. The TwDM analysis assumes the width of the slab beam is unit width without considering the lateral constraint force. The assumed conditions are obviously different from the site conditions, thus there is a certain difference between the calculated results and the field work. A three-dimensional mechanical model(ThDM)of toppling failure was established, considering that the slab beam was mainly subject to self-weight, the frictional resistance of interlayer and lateral constraint force. Due to the progressive characteristics of toppling failure, the concept and the formula of the first fracture depth(FFD) of toppling was raised and constructed. The case study indicates that the ThDM is more effective and can be accurately used to calculate the toppling fracture depth of the slab beam. The FFD decreases proportionally with the increase of slab beam width. FFD grows fast when the slab beam width is less than 2.0 m and it tends to be stable when the slab beam width is above 2.0 m. The FFD decreases with the increase of the lateral constraint coefficient, indicating that the boundary condition of the free space is positively correlated with the stability and depth of toppling. This is a good explanation of the free space effect. This study provides a reference for the stability evaluation and prevention-control design of toppling slope in the future.

关键词： boundary effect Toppling failure Three-dimensional mechanical model(ThDM) First fracture depth(FFD) Free face Slope failure

Elimination of boundary effect for laminated overburden model in pillar stability analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2016年第6期23卷 1468-1473页

作者：张鹏 K. A. Heasley Carlson Software Watertown MA 02472 USA Department of Mining Engineering West Virginia University WV 26505 USA

The laminated overburden model(La Model)has been widely used for pillar design and stability *** a boundary element program,the La Model program is sensitive to the boundary condition,which should be considered before creating the *** eliminate the boundary effect in a La Model pillar stability analysis,a suitable boundary buffer zone is needed around the model *** radius of influence(R)and the abutment load extent(D)are two major factors that affect the stresses and displacements calculated in LaM *** determine the optimum buffer zone extent,a database of case histories was analyzed using the La Model *** for R and D were varied until a buffer zone having negligible influence on the pillar stability factor(SF)of the active mining zone(AMZ)was determined.

关键词： pillar stability boundary effect LaModel numerical simulation room-and-pillar

Experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering boundary effect

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 1072-1084页

作者： Xuwei Wang Yeshuang Xu State Key Laboratory of Ocean Engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The boundary condition is a crucial factor affecting the permeability variation due to *** experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering the boundary effect is conducted,where the hydraulic head difference(DH)varies,and the boundary includes non-loss and soil-loss *** samples are filled into seven soil storerooms connected in *** evaluation,the variation in content of fine sand(ΔR_(f))and the hydraulic conductivity of soils in each storeroom(C_(i))are *** the non-loss test,the soil sample filling area is divided into runoff,transited,and accumulated areas according to the negative or positive ΔR_(f) values.ΔR_(f) increases from negative to positive along the seepage path,and Ci decreases from runoff area to transited area and then rebounds in accumulated *** the soil-loss test,all soil sample filling areas belong to the runoff area,where the gentle-loss,strengthened-loss,and alleviated-loss parts are further divided.ΔR_(f) decreases from the gentle-loss part to the strengthened-loss part and then rebounds in the alleviated-loss part,and C_(i) increases and then decreases along the seepage *** relationship between ΔR_(f) and Ci is different with the boundary *** exponentially decreases with ΔR_(f) in the non-loss test and increases with ΔR_(f) generally in the soil-loss test.

关键词： Suffusion Permeability Experimental investigation boundary effect Horizontal seepage

boundary effect of Electrophoresis: Cylinder in Cylindrical Pore

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Boundary Effect of Electrophoresis: Cylinder in Cylindrical ...

Influence of the boundary effect on the mechanical response test of pavement cushion under the wetting effect of silt

中国颗粒学会2002年年会暨海峡两岸颗粒技术研讨会

作者：徐治平高承远 Department of Chemical Engineering Taiwan University Taipei 10617 Department of Chemical Engineering Taiwan University Taipei 10617

＜正＞ Electrophoresis, one of the electrokinetic phenomena, is a widely used analytical tool in practice to characterize the surface properties of a colloidal particle. Although it has been studied extensively, the behavior of electrophoresis under general conditions has not been reported yet. In particular, when the boundary effect needs to be considered. In this case, due to the presence of complicated interactions between hydrodynamic and electric fields, solving the governing equations, which are nonlinear and coupled differential equations, is not an easy task. The boundary effect of electrophoresis is of both fundamental and practical significance. In the electrophoresis of an entity in a narrow space such as a pore, for instance, the presence of pore wall should be taken into account. Another example is the electrophoresis of a concentrated dispersion in which the interaction between neighboring particles can not be ignored. Previous results for electrophoresis are ample in the literature. Most of them, however, are based on the case when the boundary effect can be neglected, and available results for the case when this effect is taken into account are limited to simple geometries in that the end effect is insignificant. In this study, the boundary effect of electrophoresis is investigated by considering a finite cylinder in a cylindrical pore. We show that while the direction of the movement of a particle is determined by the charged conditions on its lateral surface, the magnitude of its mobility is controlled by that on its top and bottom surfaces. It was found that the mobility of a uniformly charged particle may have a local maximum as the ratio（particle radius/pore radius） varies. The mobility decreases with the increase in particle aspect ratio.

关键词： electrophoresis boundary effect finite cylinder cylindrical pore

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 Southeast University(English Edition) 2024年第3期40卷 266-274页

作者： Luo Qiqi Yu Qian Zhang Sheng Ma Xinyan Ye Xinyu Du Yinfei School of Civil Engineering Central South UniversityChangsha 410075China Department of Geotechnical Engineering China Airport Planning and Design Institute Co.Ltd.Beijing 100020China Hunan Tieyuan Civil Engineering Testing Co. Ltd.Changsha 410075China

Through a self-developed model test system,the mechanical properties of silt and the deformation characteristics of airport runways were investigated during the period of subgrade *** on the test results,the reliability of the numerical simulation results was *** models with different sizes were *** the same cushion parameter and loading width ranges,the effects of the cushion parameters and loading conditions on the mechanical responses of the cushion before and after subgrade wetting were *** results show that the internal friction angles of silt with different wetting degrees are approximately 34°.The cohesion is from 8 to 44 kPa,and the elastic modulus is from 15 to 34 *** and after subgrade wetting,the variation rates of the cushion horizontal tensile stresses with the same cushion parameters and loading width ranges are different under the influence of boundary *** subgrade wetting,the difference in the variation rates of the cushion horizontal tensile stresses under the same cushion parameter range decreases compared with that before subgrade wetting;however,this difference increases under the same loading width *** and after subgrade wetting,the influence of the boundary effect on the mechanical response evaluation of the cushion is not beneficial for optimizing the pavement design *** the cushion thickness is more than 0.25 m,the influence of the boundary effect can be disregarded.

关键词： pavement cushion silt subgrade wetting boundary effect mechanical response

Influence of boundary effect on Fracture of Concrete

在线全文

学校读者我要写书评

暂无评论

青岛理工大学学报 2010年第4期31卷 1-11页

作者： K Duan X Z Hu F H Wittmann T Zhao CQ University Gladstone Australia School of Mechanical Engineering University of Western Australia35 Stirling Highway Crawley WA 6009 Australia Aedificat Institute Freiburg Germany Qingdao Technological University Qingdao 266033 China

The recently-developed boundary effect concept and the associated asymptotic model are used to analyze size-dependent fracture of concrete *** is shown that the dependence of concrete fracture on specimen size,crack and/or ligament length is due to the same mechanism,*** interactions between the crack tip fracture process zone and specimen's *** introducing an equivalent crack length ae,dimension dependent fracture becomes equivalent to fracture of a large plate with a small edge crack,and therefore,follows the same relationship of the 'net' nominal strength σn versus *** a result,the size dependent fracture can be predicted using the data measured on different types of *** demonstrate the flexibility and effectiveness of the asymptotic boundary effect model,previously published results of three test series are *** agreement has been *** of the successful prediction are discussed.

关键词： boundary effect fracture of concrete asymptotic model

A Study of Scope Expansion and boundary effect of Economic Integration in Yangtze River Delta

在线全文

学校读者我要写书评

暂无评论

A Study of Scope Expansion and Boundary Effect of Economic I...

effect of boundary Condition on Impact Response and Damage Meso-mechanism for Scarf Bonded Repair of Load-bearing Composite Structures

作者： WU Jun YANG Qing Nanjing University Nanjing University of Technology Nanjing Normal University

The range of Yangtze River Delta economic integration has extended from the original 16 cities to the whole areas of Jiangsu province, Zhejiang province and Shanghai city since 2008, which provides useful cases for the exploration of the boundary effect of domestic regional economic integration and the policy effectiveness. By making use of the data of prefecture-level cities in Yangtze River Delta during 2001-2012 and with the help of Barro’s convergence regression equation, this paper tries to test the boundary effect of the regional economic integration, the scope expansion effect of the integration, the policy effectiveness of the scope expansion and the regional economic growth convergence respectively. The results show that there is significant boundary effect between the core of the Delta and its periphery. After the expansion,from the viewpoint of economic scale changes, there is significant negative boundary effect;from the viewpoint of labor productivity changes, there remains significant positive boundary effect, so the boundary effect does not disappear. The regional economic integration in Yangtze River Delta is earlier than the time of policy promulgation of the scope expansion, so that, the policy has the characteristics of adaptive policy adjustment. Thus it can be seen that the industrial agglomeration and diffusion in the process of the unbalanced development of regional economy is one of the causes of the regional boundary effect, the regional coordinated development policy cannot completely eliminate the boundary effect.

关键词： Scope expansion of Yangtze River Delta boundary effect policy effectiveness

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

International Journal of Plant Engineering and Management 2018年第1期23卷 7-17页

作者： LIU Bin HAN Qing LU Zhi-xian ZHONG Xiao-ping School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

Composite scarf repair is applied in airplane load-bearing structures. But the repairs would have different boundary supports in real situation, such as simply support, clamped support and flexible support. With different boundary supports, the bonded scarf repair of composite structures could have diverse damage mechanisms and responses. This work intends to study the impact performance of different boundaries. For this purpose, experimental tests were carried out on the specimens with two sides support and four sides support. The impact load and deflection was monitored during the tests. After impact being finished, the meso-mechanism was studied by means of micro-cracks of the side section for two sides support condition and cross section for the four sides support condition. It was possible to conclude that the four sides boundary possess higher impact resistance maximum loads, lower displacements and lower extent load dropping. In terms of damage modes, as the impact energy relative low 12 J and 16 J, the central position of scarf bonding zone for two sides support appears adhesive cohesive failure and adhesive-composite interface failure. When the energy increases to 20 J, the dominated damage of two sides support moves down to the feathered tip. For four sides support, the critical energy level is 25 J, under which the scarf adhesive begins to be damaged.

关键词： boundary effect repair scarf CFRP meso-mechanism micro-cracks

THE MESHLESS VIRTUAL boundary METHOD AND ITS APPLICATIONS TO 2D ELASTICITY PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2007年第1期20卷 30-40页

作者： Sun Haitao Wang Yuanhan School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China

A novel numerical method for eliminating the singular integral and boundary effect is processed. In the proposed method, the virtual boundaries corresponding to the numbers of the true boundary arguments are chosen to be as simple as possible. An indirect radial basis function network （IRBFN） constructed by functions resulting from the indeterminate integral is used to construct the approaching virtual source functions distributed along the virtual boundaries. By using the linear superposition method, the governing equations presented in the boundaries integral equations （BIE） can be established while the fundamental solutions to the problems are introduced. The singular value decomposition （SVD） method is used to solve the governing equations since an optimal solution in the least squares sense to the system equations is available. In addition, no elements are required, and the boundary conditions can be imposed easily because of the Kronecker delta function properties of the approaching functions. Three classical 2D elasticity problems have been examined to verify the performance of the method proposed. The results show that this method has faster convergence and higher accuracy than the conventional boundary type numerical methods.

关键词： numerical method singular integral boundary effect radial basis function networks integral equation virtual boundary source function singular value decomposition