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Porosity of bimodal and trimodal sediment mixtures

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International Journal of Sediment Research 2022年第2期37卷 258-271页

作者： Chamil Perera Weiming Wu Ian Knack Department of civil and Environmental engineering Clarkson University

This study focuses on the prediction of the porosity of nonuniform sediment mixtures,considering the effects of particle packing.A random particle packing model has been developed for the porosity of bimodal mixtures by extending the existing random particle filling *** in the developed model are calibrated by fitting the model to measured data for a variety of bimodal mixtures,including spherical glass particles,rounded quarry grains,and natural *** model coefficients are found to be functions of the diameter ratio of coarse and fine particles,separately for spherical glass particles and natural sediments due to differences in particle *** bimodal mixture model is then extended to trimodal particle mixtures in three approaches:two based on serial packing and one based on random *** models are tested against experimental data of six trimodal mixtures with spherical glass *** results show that the random packing model and the fine-medium-coarse particle serial packing model predict well the observed trimodal mixture porosities.

关键词： Porosity Particle filling Particle packing Bimodal mixture Trimodal mixture

Critical state model for structured soil

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Journal of Rock Mechanics and Geotechnical engineering 2020年第3期12卷 630-641页

作者： Cristhian Mendoza Marcio Muniz de Farias Department of civil engineering Universidad Nacional de Colombia Sede ManizalesManizalesColombia Department of civil and Environmental engineering University of BrasiliaBrasiliaDFBrazil

Structure is an evident determinant for macroscopic behaviors of ***,this is not taken into account in most constitutive models,as structure is a rather complex issue in *** this,it is important to develop and implement simple models that can reflect this important aspect of soil *** paper tried to model structured soils based on well-established concepts,such as critical state and *** state is the core of the classic Cam Clay *** sub-loading concept implies adoption of an inner(sub-loading)yield surface,according to specific hardening rules for some internal strain-like state *** and co-workers proposed such internal variables for controlling density(p)and structure(ω),using a modified stress space,called ***,similar variables are used in the context of the better-known invariants(p and q)of the Cam Clay *** change requires explicit adoption of a non-associated flow rule for the sub-loading *** is accomplished by modifying the dilatancy ratio of the Cam Clay model,as a function of the new internal *** modifications are described and implemented under three-dimensional(3D)*** model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured *** good agreements show the capacity and potential of the proposed model.

关键词： Elastoplasticity Cam clay with sub-loading Structured soil Tropical soil Non-associated flow rule

Nonlinear response spectrums for cable-supported glass curtain walls

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Journal of Harbin Institute of Technology(New Series) 2007年第6期14卷 827-832页

作者：周华樟武岳祝恩淳 School of civil engineering Harbin Institute of Technology

Aiming at the seismic-resistant performance of cable-supported glass curtain walls,the methods for formulating nonlinear single degree of freedom system and calculating the nonlinear response spectrums are proposed. Taking pretension effect in cables and geometrical nonlinearity into account,the nonlinear acceleration spectrums are calculated under given conditions,such as site and different seismic fortification intensities. The seismic design response spectrums are developed. During vibrating,varying period due to the influence of pretension effect in cables and geometrical nonlinearity drives the maximum period of plateau in nonlinear response spectrums to move towards the long period zone,and the maximum of seismic effect coefficient is larger than that of current seismic code. The theoretical analysis and the example demonstrate that using the nonlinear response spectrums is safe and economical.

关键词： cable-supported structure glass curtain wall nonlinear response spectrum seismic design

Analysis of Three-dimensional Crack Propagation by Using Displacement Discontinuity Method

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Journal of Donghua University(English Edition) 2010年第6期27卷 835-840页

作者：王飞黄醒春 Department of civil engineering Shanghai Jiaotong University

A technique for modelling of three-dimensional(3D)quasi-statically propagating cracks in elastic bodies by the displacement discontinuity method(DDM)was *** the crack is closed,the Mohr-coulomb rule on the two contacted surfaces of the crack must be satisfied.A simple iterative method was adopted in order to consider three different states of *** the assumption that the advance of the point on the crack front would occur only in the normal plane which is through this edge point,the maximum energy release rate criterion is modified to be used as the criterion for the crack *** discretization,the process of crack propagation can be seen as the advance of the vertices of the crack *** program MCP3D was developed based on these theories to simulate the 3D quasi-static crack propagation.A numerical example of a penny-shaped crack subject to tension and compression in an infinite elastic media was analyzed with MCP3D,and the results in comparison with others' show that the present method for 3D crack propagation is effective.

关键词： three-dimensional(3D)crack propagation displacement discontinuity method stress intensity factor(SIF) numerical simulation

Control Algorithm Using a Revised MIP Method to Deal with Livelocks in S^4R of Petri Nets

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Journal of Shanghai Jiaotong university(Science) 2019年第2期24卷 190-195页

作者： LI Shaoyong WU Zongli LI Hailin WEI Xianhong CAI Ying HOU Caiqin School of civil engineering Lanzhou University of Technology

Livelocks, like deadlocks, can result in serious results in running process of flexible manufacturing systems(FMSs). Current deadlock control policies(DCPs) based on mixed integer programming(MIP) cannot detect siphons that cause and cope with livelocks in Petri nets. This study proposes a revised mixed integer programming(RMIP) method to directly solve the new smart siphons(NSSs) associated with livelocks in a system of sequential systems with shared resources(S^4 R), a typical subclass of generalized Petri net models. Accordingly,the solved NSSs are max'-controlled by adding the corresponding control places(CPs). As a result, an original S^4 R system with livelocks can be converted into the live controlled Petri net system. The related theoretical analysis and an example are given to demonstrate the proposed RMIP and the corresponding control algorithm(CA).

关键词： flexible manufacturing system(FMS) Petri nets revised mixed integer programing(RMIP) livelocks live controlled Petri net system

Modeling the Flexural Carrying Capacity of Corroded RC Beam

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Journal of Shanghai Jiaotong university(Science) 2008年第2期13卷 129-135页

作者：王小惠刘西拉 Department of civil engineering Shanghai Jiaotong University

Considering the change of bond strength between corroded steel and concrete,flexural carrying ca- pacity of corroded reinforced concrete (RC) beam was *** the basis of the condition of equilibrium of forces and compatibility of deformations for the whole beam,a model for the prediction of flexural carrying capacity of the corroded RC beam was *** of the model's predictions with the experimental results published in the literature shows the practicality of the proposed method.

关键词： bond strength flexural capacity mechanical behavior corroded reinforced concrete beam

The Impermeability Mechanism of Self-compacting Water Proof Concrete

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Journal of Wuhan University of Technology(Materials Science) 2005年第1期20卷 121-125页

作者：李厚祥 Resource and civil engineering Institute Northeastern UniversityShenyang 110004 China civil engineering Institute Hubei University of Technology Wuhan 430068 China

The impermeability mechanism of water-proof self-compacting concrete (WPSCC )w as studied. The mechanism and influential factors, such as water-cement ratio(w /c), dosage of powder, superplasticizer, sand content, aggregate conte nt, fly ash, UEA, PP fiber, on compactibility and crack resistance of WPSCC were analyzed. A type of WPSCC successfully applied in tunnel liner with its validit ies, conveniences and economies by mockup test was developed and optimized. Expe rimental results show that the WPSCC has good workability, mechanical properties and impermeability when reasonable requirements are fulfilled.

关键词： self-compacting waterproof concrete impermeability mechanism

Flexible Optimal Model and Algorithm for Track Utilization in High-speed Railway Stations

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transportation Safety and Environment 2023年第3期5卷 30-37页

作者： Quan Gao Yinggui Zhang Zhiya Chen Yuan Chen School of Traffic&transportation engineering Central South UniversityChangsha 410075HunanChina

Track utilization is the most important technical operation in high-speed railway *** is an effective way to take flexible man-agement based on dispatchers’decision preferences into consideration for making track utilization plans to relieve the influence caused by unmeasurable unstructured ***,based on the flexible management concept and taking the flexible optimal for track utilization in high-speed railway stations as the object,time and space occupation safety trajectories of arrival routes,departure routes and tracks are all ***,taking the following constraints into consideration-minimum safety time intervals for var-ious routes and tracks occupation,space-time arc occupation and decision-makers’preferences-a flexible optimal model for track utilization in high-speed railway stations is established to maximize its balance and robustness and to minimize its volatility at the same ***,a flexible optimal solution based on a simulated annealing algorithm is designed to make a safety track utilization plan in high-speed railway stations integrating the dispatchers’decision *** results from the experiments show that the proposed methodology can effectively make satisfied safety track utilization plans based on decision-makers’preferences,which can improve its balance and robustness level ***,its volatility can be reduced as much as possible caused by flexible management based on artificial intervention to ensure the relative stability of the plan.

关键词： high-speed railway track utilization space-time network flexible management simulated annealing algorithm

Experimental study on mechanical properties of reactive powder concrete

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Journal of Harbin Institute of Technology(New Series) 2010年第6期17卷 795-800页

作者：李莉郑文忠卢姗姗 School of civil engineering Harbin Institute of Technology

The axial compressive strength,axial tensile strength,elastic modulus,poisson ratio and stress-strain relationship of RPC are obtained by compressive tests and tensile tests of RPC *** models of axial compressive and axial tensile stress-strain relationship are established,from which the equivalent coefficient of compressive and tensile stress diagram of cross-section in RPC beam are *** results provide the theory basis for the design of RPC structure and the wider popularization of RPC.

关键词： RPC mechanical properties uniaxial stress-strain relationship curve equivalent coefficent of stress diagram