检索结果-南通市图书馆

Identifying accident black spots based on the accident spacing distribution

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and transportation engineering(English Edition) 2022年第6期9卷 1017-1026页

作者： Hongjun Cui Jianguo Dong Minqing Zhu Xia Li Qingzhou Wang School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China

The identification of accident black spots is of great significance for the prevention of traffic accidents.Commonly used accident black spot identification methods divide road sections for the analysis of accident data,the direct result of which is the splitting of accident black spots,which affects the results.This paper is based on three years of traffic accident data from the Beijing-Harbin Expressway,including the time and location of traffic accidents,form of the accident fatalities,severe injuries,slight injuries,and property damage only(PDO).To avoid road division effects,an identification method based on the accident spacing distribution is established by using quality control theory.The results show that the average number of accidents per kilometer by the method proposed in this paper is 42,which is much higher than 10,identified by other identification methods.The method proposed in this paper improves the accuracy of the identification results.This method avoids the problem of road segmentation found in other common methods and can more accurately reflect the spatial distribution of traffic accidents.Thus making the identification of accidents more scientific and accurate.

关键词： Traffic accident Accident black spots Poisson distribution Accident abnormal spacing Spacing distribution

Slope stability analysis based on big data and convolutional neural network

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and civil engineering 2022年第7期16卷 882-895页

作者： Yangpan FU Mansheng LIN You ZHANG Gongfa CHEN Yongjian LIU School of Civil and Transportation Engineering Guangdong University of TechnologyGuangzhou 510006China

The Limit Equilibrium Method(LEM)is commonly used in traditional slope stability analyses,but it is time-consuming and complicated.Due to its complexity and nonlinearity involved in the evaluation process,it cannot provide a quick stability estimation when facing a large number of slopes.In this case,the convolutional neural network(CNN)provides a better alternative.A CNN model can process data quickly and complete a large amount of data analysis in a specific situation,while it needs a large number of training samples.It is difficult to get enough slope data samples in practical engineering.This study proposes a slope database generation method based on the LEM.Samples were amplified from 40 typical slopes,and a sample database consisting of 20000 slope samples was established.The sample database for slopes covered a wide range of slope geometries and soil layers’physical and mechanical properties.The CNN trained with this sample database was then applied to the stability prediction of 15 real slopes to test the accuracy of the CNN model.The results show that the slope stability prediction method based on the CNN does not need complex calculation but only needs to provide the slope coordinate information and physical and mechanical parameters of the soil layers,and it can quickly obtain the safety factor and stability state of the slopes.Moreover,the prediction accuracy of the CNN trained by the sample database for slope stability analysis reaches more than 99%,and the comparisons with the BP neural network show that the CNN has significant superiority in slope stability evaluation.Therefore,the CNN can predict the safety factor of real slopes.In particular,the combination of typical actual slopes and generated slope data provides enough training and testing samples for the CNN,which improves the prediction speed and practicability of the CNN-based evaluation method in engineering practice.

关键词： slope stability limit equilibrium method convolutional neural network database for slopes big data

Traffic control optimization strategy based on license plate recognition data

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

Journal of Traffic and transportation engineering(English Edition) 2023年第1期10卷 45-57页

作者： Ruimin Li Shi Wang Pengpeng Jiao Shichao Lin Institute of transportation engineering Tsinghua UniversityBeijing 100084China Department of civil engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA School of Civil and Transportation Engineering Beijing University of Civil Engineering and ArchitectureBeijing 100044China

Traffic signal control is essential to the efficiency of the road network’s operation.In recent years,more and more detailed detection data provide potential data support for traffic signal control,such as license plate recognition(LPR)data.This study aims to develop a traffic signal control optimization method based on model predictive control(MPC)and LPR data.The proposed framework of a closed-loop control system is described in detail.First,the control objectives and queue prediction model for signalized intersection are determined.Then,online optimization and feedback compensation are discussed and implemented.Calculations of the arrival rate at the downstream are based on the LPR data detected at the upstream intersection,and dynamic optimization method of the offset is proposed for a coordinated control.The model is validated using the LPR data of two consecutive intersections with a traffic simulation platform.Results demonstrate that the model can restrain extreme long queuing,improve intersection capacity,and reduce intersection average delay.The developed model promotes the system operating efficiency and shows the general advantage of real-time optimization,feedback,and control.The proposed framework can be potentially applied by local traffic management centers to improve the quality of traffic signal control.

关键词： Traffic control Model predictive control Closed-loop control License plate recognition data

Seismic performance analysis of underground structures based on random field model of soil mechanical parameters

在线全文

学校读者我要写书评

暂无评论

Earthquake Research Advances 2022年第4期2卷 3-10页

作者： Chao Ma Shenghui Zhou Jingwei Chi School of Civil and Transportation Engineering Beijing University of Civil Engineering and ArchitectureBeijing102616China

Soils with spatial variability are the product of natural history.The mechanical properties tested by soil samples from boreholes in the same soil layer may be different.Underground structure service in surrounding soils,their seismic response is controlled by the deformation of the surrounding soils.The variability of soil mechanical parameters was not considered in the current research on the seismic response of underground structures.Therefore,a random field model was established to describe the spatial variability of surrounding soils based on the random field theory.Then the seismic response of underground structures in the random field was simulated based on the time-domain explicit global FEM analysis,and the soil mechanical parameters and earthquake intensity influencing the seismic response of surrounding soils and underground structures were studied.Numerical results presented that,the randomness of soil parameters does not change the plastic deformation mode of surrounding soils significantly.The variation coefficients of inter-story deformation of structures and lateral deformation of columns are much smaller than that of mechanical parameters,and the randomness of soil parameters has no obvious effect on the structural deformation response.

关键词： Underground structures Random field Seismic performance FEM analysis Variable coefficient

在线全文

学校读者我要写书评

暂无评论

黄泛区非饱和粉土动模量和阻尼比特性研究

Journal of Central South University 2024年第1期31卷 237-249页

作者：彭飞李梦瑶李永辉黄茂松 school of civil engineering Zhengzhou UniversityZhengzhou 450001China school of transportation Southeast UniversityNanjing 210096China school of civil engineering Tongji UniversityShanghai 200092China

黄泛区粉土水敏感性强,力学性质独特,易受振动荷载的影响。本文通过循环三轴试验,研究固结围压和饱和度对黄泛区粉土动模量、阻尼比特性的影响。研究结果表明,黄泛区粉土骨干曲线符合双曲线关系;随动应变的增大,黄泛区粉土动弹性模量先... 详细信息

黄泛区粉土水敏感性强,力学性质独特,易受振动荷载的影响。本文通过循环三轴试验,研究固结围压和饱和度对黄泛区粉土动模量、阻尼比特性的影响。研究结果表明,黄泛区粉土骨干曲线符合双曲线关系;随动应变的增大,黄泛区粉土动弹性模量先急剧减小而后逐渐趋于稳定;随固结围压的增大和饱和度的减小,粉土动弹性模量逐渐增大,阻尼比则逐渐减小;二元线性方程可用于估算最大动弹性模量随固结围压和饱和度的变化规律,修正Hardin-Drnevich模型可较为准确预测黄泛区非饱和粉土的动弹性模量和阻尼比。本研究可为黄河流域工程建设提供理论支撑。

关键词：黄泛区非饱和粉土动弹性模量阻尼比计算模型

Effect of Chlorine Salt on Durability of Mineral Admixture Concrete under Different Conditions

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

Journal of Renewable Materials 2022年第9期10卷 2489-2508页

作者： Xupeng Chen Zhuowen Sun Jianyong Pang school of civil engineering and Architecture Anhui University of Science and EngineeringHuainan232001China school of transportation and civil engineering Nantong UniversityNantong226019China

Mineral admixture concrete is a renewable material.It requires less cement than ordinary concrete and is thus beneficial for economical use of resources and environmental protection.To examine the impact of chloride salt on the durability of mineral admixture concrete under various conditions,in this study,test blocks are divided into two major groups:in one group,the test block is eroded by chloride salt on the interior and by sulphate/magnesium salts on the exterior,and in the second group,the test block is eroded by external chloride/sulphate/magnesium salts.Clean water is considered the control group.Dry-wet alternation tests are carried out to investigate the mechanical properties,mass,macromorphology,and ion content of the concrete.Furthermore,a series of methods,such as XRD,FT-IR,SEM,and EDS,are adopted to examine the phase composition and micromorphology of the concrete.The results show that,for the concrete subjected to the corrosion of internal chloride salt and external sulphate/magnesium salts(0–20 cycles),its mechanical properties improve slowly at the initial stage,but at the final stage(80–120 cycles),it is subjected to more severe corrosion compared to those only eroded by a single corrosive ion,such as the chloride/sulfate/magnesium salts.For concretes subjected to external corrosion of chloride/sulphate/magnesium salts,the concrete durability enhances with the concentration increase of the chloride salt.Mg^(2+)and SO_(4)^(2-)could jointly result in destructive damage to the admixture concrete,main generating corrosion products of ettringite,gypsum,Mg(OH)2,thaumasite,and M-S-H.

关键词： External corrosion internal corrosion corrosive ions dry-wet alternation durability

Research on the influence of grouted sleeves and assembled seams on the deformation and bearing capacity of compression-flexure member

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

Earthquake Research Advances 2022年第4期2卷 46-52页

作者： Hongtao Liu Pengchao Kong Zuohu Wang Weizhang Liao School of Civil and Transportation Engineering Beijing Univ.of Civil Engineering and ArchitectureBeijing100044China

Grouted sleeves can effectively connect precast elements,but the effect of grouted sleeves for increased stiffness and assembled seam for weakening stiffness on the precast column’s mechanical properties is unclear.Based on the full-scale test results of precast columns connected with grouted sleeves and the correctness of the numerical models,the influence analysis of the individual and coupling action of the grouted sleeves and assembled seam on the deformation and bearing capacity of the precast column is carried out.The research results show that grouted sleeves significantly affect the deformation and peak bearing capacity of precast columns;when precast columns are subjected to the action of high axial pressure,grouted sleeves significantly affect the bearing capacity.However,the influence of assembled seams on the peaking capacity of the precast column is more obvious when it was tested under low axial compression.It is recommended that the connection position should be 2 times the height of the grouted sleeve from the bottom of the foundation.

关键词： Precast column Grouted sleeves Assembled seam Deformation Strength Numerical analysis

Heterogeneous traffic flow modeling with drivers’ timid and aggressive characteristics

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第10期30卷 219-230页

作者：翟聪巫威眺罗淞文 school of civil engineering and transportation South China University of TechnologyGuangzhou 510641China school of transportation and civil engineering and Architecture Foshan UniversityFoshan 528000China

The driver’s characteristics(e.g.,timid and aggressive)has been proven to greatly affect the traffic flow performance,whereas the underlying assumption in most of the existing studies is that all drivers are homogeneous.In the real traffic environment,the drivers are distinct due to a variety of factors such as personality characteristics.To better reflect the reality,we introduce the penetration rate to describe the degree of drivers’heterogeneity(i.e.,timid and aggressive),and proceed to propose a generalized heterogeneous car-following model with different driver’s characteristics.Through the linear stability analysis,the stability conditions of the proposed heterogeneous traffic flow model are obtained based on the perturbation method.The impacts of the penetration rate of drivers with low intensity,the average value and standard deviation of intensity parameters characterizing two types of drivers on the stability of traffic flow are analyzed by simulation.Results show that higher penetration of aggressive drivers contributes to traffic flow stability.The average value has a great impact on the stability of traffic flow,whereas the impact of the standard deviation is trivial.

关键词： heterogeneous car-following model driver characteristic penetration rate stability

考虑渗流效应的深基坑大型止水屏障分析方法及其应用

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2022年第6期29卷 2033-2048页

作者：曹成勇施成华 College of civil and transportation engineering Shenzhen UniversityShenzhen 518060China school of civil engineering Central South UniversityChangsha 410075China

本文介绍了一种深基坑大型止水屏障(部分重叠的高压旋喷桩组成)的分析方法,该方法考虑了其两个关键的因素(渗透性与材料强度)。随后,通过对一个算例进行了分析和讨论。结果表明,在基坑止水屏障参数设计时应主要考虑其拉裂破坏模式,其中... 详细信息

本文介绍了一种深基坑大型止水屏障(部分重叠的高压旋喷桩组成)的分析方法,该方法考虑了其两个关键的因素(渗透性与材料强度)。随后,通过对一个算例进行了分析和讨论。结果表明,在基坑止水屏障参数设计时应主要考虑其拉裂破坏模式,其中最大允许渗流量是重要的设计指标之一,其对确定基坑止水屏障设计参数具有十分显著的影响。与本文提出的设计方法相比,由于忽略止水屏障结构自身渗透性能和材料强度对结构安全的贡献,采用稳定平衡法或渗流稳定平衡法进行确定基坑止水屏障设计参数是相对保守的。在此基础上,以福州地铁某深基坑工程为例,采用本文提出的设计方法,确定了深基坑止水屏障厚度与深度的范围值。最后,现场抽水试验结果表明现场基坑止水屏障的水密性能十分良好。

关键词：矩形基坑深层含水层大型止水屏障渗流设计方法