检索结果-南通市图书馆

Finite Element Simulations on Failure Behaviors of Granular Materials with Microstructures Using a Micromechanics-Based Cosserat Elastoplastic Model

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in engineering & Sciences 2024年第3期138卷 2305-2338页

作者： Chenxi Xiu Xihua Chu school of civil engineering Chongqing Jiaotong UniversityChongqing400074China school of civil engineering Wuhan UniversityWuhan430072China

This paper presents a micromechanics-based Cosserat continuum model for microstructured granular materials.By utilizing this model,the macroscopic constitutive parameters of granular materials with different microstructures are expressed as sums of microstructural information.The microstructures under consideration can be classified into three categories:a medium-dense microstructure,a dense microstructure consisting of one-sized particles,and a dense microstructure consisting of two-sized particles.Subsequently,the Cosserat elastoplastic model,along with its finite element formulation,is derived using the extended Drucker-Prager yield criteria.To investigate failure behaviors,numerical simulations of granular materials with different microstructures are conducted using the ABAQUS User Element(UEL)interface.It demonstrates the capacity of the proposed model to simulate the phenomena of strain-softening and strain localization.The study investigates the influence of microscopic parameters,including contact stiffness parameters and characteristic length,on the failure behaviors of granularmaterials withmicrostructures.Additionally,the study examines themesh independence of the presented model and establishes its relationship with the characteristic length.A comparison is made between finite element simulations and discrete element simulations for a medium-dense microstructure,revealing a good agreement in results during the elastic stage.Somemacroscopic parameters describing plasticity are shown to be partially related to microscopic factors such as confining pressure and size of the representative volume element.

关键词： Granular materials micromechanics Cosserat elastoplastic model microstructures failure behaviors

Mechanism of local scour around submarine pipelines based on numerical simulation of turbulence model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2006年第2期25卷 142-152页

作者： L Lin1*, LI Yucheng1,3, CHEN Bing21. State Key Laboratory of Coastal and Offshore engineering, Dalian University of Technology, Dalian 116024, China2. school of civil and hydraulic engineering, Dalian University of Technology, Dalian 116024, China3. R&D center of civil engineering Technology, Dalian University, Dalian 116622, ChinaReceived 20 July 2005 accepted 14 December 2005 State Key Laboratory of Coastal and Offshore engineering Dalian University of Technology Dalian 116024 China RandD Center of civil engineering Technology Dalian University Dalian 116622 China school of civil and hydraulic engineering Dalian University of Technology Dalian 116024 China

The mechanism of local scour around submarine pipelines is studied numerically based on a renormalized group (RNG) turbulence model. To validate the numerical model, the equilibrium profiles of local scour for two cases are simulated and compared with the experimental data. It shows that the RNG turbulence model can give an appropriate prediction for the configuration of equilibrium scour hole, and it is applicable to this situation. The local scour mechanism around submarine pipelines including the flow structure, shear stress distribution and pressure field is then analyzed and compared with experiments. For further comparison and validation, especially for the flow structure, a numerical calculation employing the large eddy simulation (LES) is also conducted. The numerical results of RNG demonstrate that the critical factor governing the equilibrium profile is the seabed shear stress distribution in the case of bed load sediment transport, and the two-equation RNG turbulence model coupled with the law of wall is capable of giving a satisfying estimation for the bed shear stress. Moreover, the piping phenomena due to the great difference of pressure between the upstream and downstream parts of pipelines and the vortex structure around submarine pipelines are also simulated successfully, which are believed to be the important factor that lead to the onset of local scour.

关键词： submarine pipeline mechanism of local scour renormalized group turbulence model large eddy simulation piping

Limit load and failure mechanisms of a vertical Hoek-Brown rock slope

同方期刊数据库评论

在线全文

同方期刊数据库

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 1106-1111页

作者： Jim Shiau Warayut Dokduea Suraparb Keawsawasvong Pitthaya Jamsawang school of engineering University of Southern QueenslandToowoomba4350QLDAustralia Department of civil engineering Faculty of EngineeringKing Mongkut’s University of Technology ThonburiBangkokThailand Research Unit in Sciences and Innovative Technologies for civil engineering Infrastructures Department of Civil EngineeringThammasat School of EngineeringThammasat UniversityPathumthani12120Thailand Soil engineering Research Center Department of Civil EngineeringKing Mongkut’s University of Technology North BangkokBangkok10800Thailand

The problem considered in this short note is the limit load determination of a vertical rock slope.The classical limit theorem is employed with the use of adaptive finite elements and nonlinear programming to determine upper and lower bound limit loads of a Hoek-Brown vertical rock slope.The objective function of the mathematical programming problem is such as to optimize a boundary load,which is known as the limit load,resembling the ultimate bearing capacity of a strip footing.While focusing on the vertical slope,parametric studies are carried out for several dimensionless ratios such as the dimensionless footing distance ratio,the dimensionless height ratio,and the dimensionless rock strength ratio.A comprehensive set of design charts is presented,and failure envelopes shown with the results explained in terms of three identified failure mechanisms,i.***.the face,the toe,and the Prandtl-type failures.These novel results can be used with great confidence in design practice,in particularly noting that the current industry-based design procedures for the presented problem are rarely found.

关键词： Bearing capacity Rock slope Vertical slope Finite element limit analysis Hoek-Brown yield criterion

Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2024年第7期90卷 535-557页

作者： Ke Cao Huisu Chen Mohammad Iqbal Khan Mingqi Li Lin Liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Department of civil engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia school of civil and Transportation engineering Hebei University of TechnologyTianjin 300401China College of civil and Transportation engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method Granular media

Inter-basin water transfer-supply model and risk analysis with consideration of rainfall forecast information

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第12期53卷 3316-3323页

作者： XI ShuFeng1, WANG BenDe1, LIANG GuoHua1, LI XueSen2 & LOU LiLi3 1 school of civil and hydraulic engineering, Dalian University of Technology, Dalian 116024, China 2 Management Bureau of Tanghe Reservoir, Liaoyang 111000, China 3 Institute of Dalian Water Science, Dalian 116013, China school of civil and hydraulic engineering Dalian University of Technology Dalian China Management Bureau of Tanghe Reservoir Liaoyang China Institute of Dalian Water Science Dalian China

This paper develops a new inter-basin water transfer-supply and risk assessment model with consideration of rainfall forecast information. Firstly, based on the current state of reservoir and rainfall forecast information from the global forecast system (GFS), the actual diversion amount can be determined according to the inter-basin water transfer rules with the decision tree method; secondly, the reservoir supply operation system is used to distribute water resource of the inter-basin water transfer reservoir; finally, the integrated risk assessment model is built by selecting the reliability of water transfer, the reliability (water shortage risk), the resiliency and the vulnerability of water supply as risk analysis indexes. The case study shows that the inter-basin water transfer-supply model with rainfall forecast information considered can reduce the comprehensive risk and improve the utilization efficiency of water resource, as compared with conventional and optimal water distribution models.

关键词： inter-basin water transfer GFS rainfall forecast water distribution risk assessment

Simplified seismic scenario analysis of existing masonry buildings accounting for local site effects

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and civil engineering 2024年第2期18卷 309-318页

作者： Ayşe E.ÖZSOYÖZBAY Işıl SANRI KARAPINAR Zehra N.KUTLU İsmail E.KILIÇ Department of civil engineering Maltepe UniversityIstanbul 34857Turkey school of engineering and Construction Oryx Universal CollegeDoha 12253Qatar

This study discusses the effects of local sites and hazard amplification on the seismic vulnerability assessment of existing masonry buildings.In this context,a rapid seismic evaluation procedure was implemented on an old masonry building stock in the historical center Galata,located inİstanbul,to determine the seismic risk priority of the built heritage.Damage scenarios were generated for all soil classes,different moment magnitudes,and source-to-site distances to obtain more accurate results for the seismic vulnerability assessment of the studied building stock.Consequently,damage distributions estimated under nine different scenarios with/without site effects were compared and illustrated in maps to discuss changes in vulnerability owing to amplification effects.In this study,by re-examining the rapid seismic evaluation procedure by including geo-hazard-based assessment,the importance of site effects on the vulnerability and risk assessment of built heritage was underlined.The proposed framework integrating field data and local site effects is believed to advance the current applications for vulnerability assessment of masonry buildings and provide an improvement in the application of rapid seismic assessment procedures with more reliable results.

关键词： masonry buildings seismic vulnerability assessment cultural heritage local site effect

MCDM technique using single-valued neutrosophic trigonometric weighted aggregation operators

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 Management Analytics 2024年第1期11卷 45-61页

作者： Jun Ye Shigui Du Rui Yong school of civil and Environmental engineering Ningbo UniversityNingboPeople’s Republic of China

Motivated based on the trigonometric t-norm and t-conorm,the aims of this article are to present the trigonometric t-norm and t-conorm operational laws of SvNNs and then to propose the SvNN trigonometric weighted average and geometric aggregation operators for the modelling of a multiple criteria decision making(MCDM)technique in an inconsistent and indeterminate circumstance.To realize the aims,this paper first proposes the trigonometric t-norm and t-conorm operational laws of SvNNs,which contain the hybrid operations of the tangent and arctangent functions and the cotangent and inverse cotangent functions,and presents the SvNN trigonometric weighted average and geometric operators and their properties.Next,an MCDM technique is proposed in view of the presented two aggregation operators in the circumstance of SvNNs.In the end,an actual case of the choice issue of slope treatment schemes is provided to indicate the practicability and effectivity of the proposed MCDM technique.

关键词： Single-valued neutrosophic number trigonometric t-norm and t-conorm trigonometric weighted aggregation operator decision making

Sungai Lembing’s green tourism: Pioneering the future of resourcebased urban renewal

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Innovation 2024年第2期5卷 19-20页

作者： Haoxuan Yu Ginura Gunaratna Izni Zahidi Chow Ming Fai Department of civil engineering School of EngineeringMonash University MalaysiaBandar SunwaySelangor 47500Malaysia

HOW DID SUNGAI LEMBING PAVE ITS PATH TO A GREEN EVOLUTION?Sungai Lembing,a resource-based town situated in Pahang,Malaysia,has historically positioned itself as a pivotal hub in the global tin mining sector.Geologically,Sungai Lembing’s history dates back to the Paleozoic and Mesozoic eras.These eras were marked by the closure of the Tethyan Ocean and the convergence of continental landmasses from the eastern part of the Gondwana continent.This complex geological background resulted in a wide variety of mineral resources.

关键词： situated eastern Pioneer

An Investigation into the Compressive Strength,Permeability and Microstructure of Quartzite-Rock-Sand Mortar

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2024年第4期20卷 859-872页

作者： Wei Chen Wuwen Liu Yue Liang school of civil engineering Architecture and EnvironmentHubei University of TechnologyWuhan430068China

River sand is an essential component used as a fine aggregate in mortar and concrete.Due to unrestrained exploitation,river sand resources are gradually being exhausted.This requires alternative solutions.This study deals with the properties of cement mortar containing different levels of manufactured sand(MS)based on quartzite,used to replace river sand.The river sand was replaced at 20%,40%,60%and 80%with MS(by weight or volume).The mechanical properties,transfer properties,and microstructure were examined and compared to a control group to study the impact of the replacement level.The results indicate that the compressive strength can be improved by increasing such a level.The strength was improved by 35.1%and 45.5%over that of the control mortar at replacement levels of 60%and 80%,respectively.Although there was a weak link between porosity and gas permeability in the mortars with manufactured sand,the gas permeability decreased with growing the replacement level.The microstructure of the MS mortar was denser,and the cement paste had fewer microcracks with increasing the replacement level.

关键词： Manufactured sand quartzite compressive strength gas permeability microstructure