桥梁抗倾覆验算及加固设计

文章以工程实例为背景,介绍了桥梁抗倾覆验算结构建模、荷载取值、边界条件模拟以及验算的注意事项,并分析了抗倾覆加固设计的基本要求和主要方法,可为类似工程提供参考。     

深基坑坑底土体抗隆起稳定性的验算方法辨析

深基坑抗隆起验算是基坑设计中的一项重要内容。本文对现有技术标准中有关基坑抗隆起稳定性验算的内容进行了系统的梳理,并就验算模式的适用条件、计算参数的取值和抗隆起安全度的指标值等提出了一些建议,推导和完善了部分计算公式,以供同行参考。     

重载交通沥青路面高温抗剪性能研究

文章通过总结国内外有关重载交通和抗剪性能的研究成果,推荐了高温和重载综合影响下评价路面抗剪性能的方法,以评价高温和重载因素对沥青路面结构性能的影响,同时也为降低沥青面层剪应力措施的设计与施工提供借鉴。     

高速公路边坡支护工程优化设计研究

文章结合某高速公路边坡工程实例,通过大型剪切试验获取结构面参数,分析了公路边坡支护优化设计方案。通过现场大型剪切试验结果可知,饱和条件下各试样的抗剪强度参数均有所下降,相同试验条件下试样的残余抗剪强度参数均低于峰值抗剪强度参数,针对已经产生滑动破坏的边坡支护设计时宜采用残余抗剪强度参数。使用现场实测参数优化后,可节约边坡支护成本。     

沉管隧道节段接头混凝土剪力键与摩擦力协同抗剪机理试验研究

文章通过沉管隧道节段接头抗剪机理室内缩尺模型试验,测试了接头在不同接触应力状态及不同剪力键垫层厚度等工况下,混凝土剪力键与接触面摩擦力协同抗剪受力模式。结果表明,摩擦力对接头抗剪强度贡献显著而且可靠。     

高拱坝混凝土原位抗剪试验研究

通过对混凝土层间结合面进行原位抗剪试验,获得各级配混凝土不同层间处理方式的极限抗剪强度、残余抗剪强度、摩擦强度和抗剪特性参数f′、c′,为优化大坝混凝土层间处理措施、评估坝体结构稳定性提供依据。     

混凝土桥面界面处置方式的研究和探讨

本文结合杭州湾跨海大桥混凝土桥面铺装界面处置的具体施工情况,简要的介绍了两种界面处置方法的施工工艺。同时,通过试验对比研究,从形成界面的构造深度、抗剪能力等方面就两种界面处置方法进行了对比。另外,本文提出了在混凝土桥面铺装中,在同等粘结防水材料的情况下,铣刨较喷砂处理能提供更为安全的抗剪界面的观点。     

桥梁斜截面抗剪工况静载试验计算分析

文章以实际工程桥梁静载试验为例,介绍支点附近斜截面抗剪工况的静载试验方法,对比采用Midas杆系模型和Ansys实体模型计算的斜截面应力理论值,结合静载试验的实测数据分析和理论数据分析,得到斜截面抗剪工况理论值。经计算发现,采用杆系模型计算的结果存在较大偏差,会造成静载试验的评定结果不合理。因此,进行支点附近斜截面抗剪工况理论应变计算时应采用实体模型。     

地下埋管裂缝原因分析及抗裂验算方法

本文对地下埋管多年运行后产生环向裂缝的原因进行分析，提出了地下埋管轴向抗裂验算方法，对判别已建地下埋管工程是否裂缝提供了理论依据，因此该方法可用于工程设计之中。     

铅芯橡胶支座在厦漳跨海大桥北汊北引桥抗震中的应用

以厦漳跨海大桥北汉北引桥为例,结合新颁布的《公路桥梁抗震设计细则》中特殊桥梁抗震验算理论,采用非线性时程计算方法对该桥的常规强度抗震方案及采用铅芯橡胶支座减震方案进行了对比计算,并对桥墩及桩基的地震反应采用特殊桥梁的性能目标进行了分析验算,计算结果表明,当遭受强地震作用时,采用铅芯橡胶支座的桥梁结构整体还在弹性范围,抗...     

基于增量搜索的车辆动态路径规划算法研究

D＊Lite算法是一种非常高效的增量搜索算法,适合于动态环境下的路径规划。文章基于D＊Lite算法的原理,对该算法的性能及应用于车辆路径规划的适用性进行改进,提高了算法的稳定性和结果的可靠性,并通过试验和算法评价验证了改进的D＊Lite算法在复杂、动态环境下规划路径的有效性。     

基于两种拱盖法修建的青岛地区上软下硬岩质地层大跨隧道结构稳定性研究

拱盖法是基于纵深刚度差异较大的“上软下硬”地层条件,在充分吸取盖挖法、双侧壁导坑法等工法的成功经验或者不足之处的基础上发展起来的一种暗挖大跨隧道修建技术,拱盖法主要有双层初期支护拱盖法和二次衬砌拱盖法。文章以青岛地铁某暗挖大跨车站为例,结合站址范围内上软下硬复合地层的特征,通过数值方法对两种拱盖法修筑的隧道结构稳定性进行分析研究。结果表明:1)二次衬砌拱盖法采用纵向9 m拆撑安全步距施工时,外层初期支护棚护作用的“空间刚度效应”不足以弥补其拱盖的“拱”效应,双层初期支护拱盖法修筑技术更有利于隧道变形控制;2)隧道下部岩体开挖时拱盖结构的承载、保护作用显著,但在相同等地质环境条件下,二次衬砌拱盖法施工对拱脚岩体的塑性破坏作用更明显,换言之即二次衬砌拱脚对岩基的强度和刚度要求更高;3)初期支护拱盖法结构受力控制部位为拱肩及拱脚,二次衬砌拱盖法结构受力控制部位为拱脚,后者拱脚控制内力约为前者的1.56倍,前者的“梁”效应比较明显,后者的“脚”效应比较明显;4)为地铁百年服务工程安全计,建议优先考虑采用双层初期支护拱盖法施工。     

High accuracy crash mapping using fuzzy logic

Accurate crash location data in crash databases can be shown to be essential for crash modelling, crash mapping, hazardous road segment identification and other studies that aim to decrease the number of crashes within a network area. In this paper a generic and high-accuracy automatic crash mapping method is developed and presented. The methodology is based on a transformed map-matching method for candidate road segment identification and on a fuzzy logic inference system for the final road segment selection. The method is implemented by employing all injury and fatal crashes that occurred during 2012 in the UK Strategic Road Network but can be transferred to other network/crash data. The accuracy of the developed method is estimated to be 98.9% (±1.1%) correct matches. The results of this method are compared to other less advanced crash mapping methods.     

Large-scale evacuation network optimization: a bi-level control method with uncertain arterial demand

To improve the efficiency of large-scale evacuations, a network aggregation method and a bi-level optimization control method are proposed in this paper. The network aggregation method indicates the uncertain evacuation demand on the arterial sub-network and balances accuracy and efficiency by refining local road sub-networks. The bi-level optimization control method is developed to reconfigure the aggregated network from both supply and demand sides with contraflow and conflict elimination. The main purpose of this control method is to make the arterial sub-network to be served without congestion and interruption. Then, a corresponding bi-objective network flow model is presented in a static manner for an oversaturated network, and a Genetic Algorithm-based solution method is used to solve the evacuation problem. The numerical results from optimizing a city-scale evacuation network for a super typhoon justify the validity and usefulness of the network aggregation and optimization control methods.     

The estimation of a time-dependent OD trip table with vehicle trajectory samples

Abstract

In this paper we discuss a dynamic origin–destination (OD) estimation problem that has been used for identifying time-dependent travel demand on a road network. Even though a dynamic OD table is an indispensable data input for executing a dynamic traffic assignment, it is difficult to construct using the conventional OD construction method such as the four-step model. For this reason, a direct estimation method based on field traffic data such as link traffic counts has been used. However, the method does not account for a logical relationship between a travel demand pattern and socioeconomic attributes. In addition, the OD estimation method cannot guarantee the reliability of estimated results since the OD estimation problem has a property named the ‘underdetermined problem.’ In order to overcome such a problem, the method developed in this paper makes use of vehicle trajectory samples with link traffic counts. The new method is applied to numerical examples and shows promising capability for identifying a temporal and spatial travel demand pattern.     

预应力混凝土变宽箱梁活载内力计算研究

介绍了单箱多室变宽箱梁活载内力计算原理及在设计过程中的简化计算方法。以实桥为例,将各种简化计算方法的计算值与空间有限单元法计算值进行比较,探讨设计方法的可行性。最后推荐在设计过程中应采用的较合理的计算方法。     

深基坑支护中的SMW工法

SMW工法是近年来兴起的一种新的深基坑围护形式,由于其具有无渗漏水、造价低等诸多优点,已得到越来越广泛的应用。文章结合工程实例,介绍SMW工法施工工艺及其操作要点,供同类型施工参考。     

A robust method for estimating transit passenger trajectories using automated data

Development of an origin-destination demand matrix is crucial for transit planning. The development process is facilitated by automated transit smart card data, making it possible to mine boarding and alighting patterns on an individual basis. This research proposes a novel trip chaining method which uses Automatic Fare Collection (AFC) and General Transit Feed Specification (GTFS) data to infer the most likely trajectory of individual transit passengers. The method relaxes the assumptions on various parameters used in the existing trip chaining algorithms such as transfer walking distance threshold, buffer distance for selecting the boarding location, time window for selecting the vehicle trip, etc. The method also resolves issues related to errors in GPS location recorded by AFC systems or selection of incorrect sub-route from GTFS data. The proposed trip chaining method generates a set of candidate trajectories for each AFC tag to reach the next tag, calculates the probability of each trajectory, and selects the most likely trajectory to infer the boarding and alighting stops. The method is applied to transit data from the Twin Cities, MN, which has an open transit system where passengers tap smart cards only once when boarding (or when alighting on pay-exit buses). Based on the consecutive tags of the passenger, the proposed algorithm is also modified for pay-exit cases. The method is compared to previous methods developed by the researchers and shows improvement in the number of inferred cases. Finally, results are visualized to understand the route ridership and geographical pattern of trips.     

应用层次分析法评价最优运行的输气管道

为了更好地评价在役输气管道运行的优劣，应用层次分析法建立评价最优运行输气管道指标体系及结构模型，从多因素、定量与定性相结合的角度来确定最优运行的输气管道。层次分析法为输气管道的运营管理提供了一种有效的方法。同时，为实现管道最优运行采取具体措施和新管道的设计提供了辅助决策。     

Pedestrian detection for traffic safety based on Accumulate Binary Haar features and improved deep belief network algorithm

ABSTRACT

In order to improve traffic safety and protect pedestrians, an improved and efficient pedestrian detection method for auto driver assistance systems is proposed. Firstly, an improved Accumulate Binary Haar (ABH) feature extraction algorithm is proposed. In this novel feature, Haar features keep only the ordinal relationship named by binary Haar features. Then, the feature brings in the idea of a Local Binary Pattern (LBP), assembling several neighboring binary Haar features to improve discriminating power and reduce the effect of illumination. Next, a pedestrian classification method based on an improved deep belief network (DBN) classification algorithm is proposed. An improved method of input is constructed using a Restricted Bolzmann Machine (RBM) with T distribution function visible layer nodes, which can convert information on pedestrian features to a Bernoulli distribution, and the Bernoulli distribution can then be used for recognition. In addition, a middle layer of the RBM structure is created, which achieves data transfer between the hidden layer structure and keeps the key information. Finally, the cost-sensitive Support Vector Machine (SVM) classifier is used for the output of the classifier, which could address the class-imbalance problem. Extensive experiments show that the improved DBN pedestrian detection method is better than other shallow classic algorithms, and the proposed method is effective and sufficiently feasible for pedestrian detection in complex urban environments.