某高速公路水泥路面养护项目铣刨及刻槽工艺的适用性分析

铣刨及刻槽工艺作为水泥路面养护常用技术手段,对提高高速公路路用性能具有重要作用。结合某高速公路实际工程案例,通过现场试验检测及理论对比,全面阐述铣刨、刻槽工艺的具体适用范围,综合分析两种养护技术对高速公路路用性能的影响,为后续高速公路养护施工提供参考。     

碾压贫混凝土配合比试验设计初探

由于特于硬性碾压贫混凝土设计在国内还处于探索和研究阶段，本文通过对特于硬性碾压贫混凝土配合比的试验设计，总结出特于硬性碾压贫混凝土设计的经验公式和制做方法，对特于硬性碾压贫混凝土施工技术理论提出了一些经验性和指导性的方法和观点，对我国特于硬性碾压贫混凝土基础技术理论做了一些有益的探索。     

基于槽壁稳定性的地下连续墙成槽施工泥浆重度计算方法

文章采用极限平衡法,分别建立了地下连续墙成槽施工槽壁土体整体稳定性和局部稳定性力学模型,推导得到了保证槽壁稳定的成槽施工泥浆重度临界值计算公式,形成了基于槽壁稳定性的地下连续墙成槽施工泥浆重度设计方法,并进行了实例应用。结果表明:所建立的泥浆重度设计计算方法是可靠的,且在类似工程的松散砂卵地层中,宜采用考虑槽壁局部稳定时的泥浆设重度计算值。     

马王槽大桥弓弦式挂篮设计及应用

结合万梁高速马王槽大桥悬灌施工实际,介绍弓弦式挂篮的设计、应用及施工注意事项。     

严寒地区公路隧道水沟及电缆槽施工技术

大武至久治公路隧道位于青藏高原,气候寒冷,水沟电缆槽作为附属工程,一般都是作为施工最后一道工序,严寒地区冬期施工期间仍然组织水沟电缆槽施工,为了防止砼发生冻胀现象,确保隧道内砼施工温度。隧道水沟电缆槽施工质量直接关系隧道工程的形象,施工过程须严格把控。针对以上问题,本文总结出了寒区隧道水沟及电缆槽施工技术,为今后寒冷地区隧道水沟电缆槽施工提供借鉴。     

上软下硬地层地下连续墙成槽施工

广州地铁一号线公园前站地下连续墙槽段开挖,因地质条件变化,经历了不同的施工阶段,特别是在上软下硬地层成槽施工中历经了艰难,同时亦积累和形成了在此类地层中地下连续墙成槽施工技术的经验.     

旋喷桩加固在地铁车站地下连续墙成槽中的应用

地下连续墙在复杂地质条件下，尤其是在呈流塑状淤泥层的地质情况下进行施工的成槽难度很大，本文结合广州地铁六号线天河客运站围护结构地下连续墙成槽的施工实例，对成槽前的加固方案比选进行了较详细的论述。总结出一套行之有效的加固措施及施工控制措施，减少了施工费用争取了工期，对类似工程有很好的参考价值。     

齐岳山隧道富水溶槽注浆堵水技术

齐岳山隧道进口端采取反坡施工,隧道施工到DK362 060处遇到富水溶槽。文章主要介绍了该富水溶槽的注浆设计方案、注浆材料及堵水技术。     

富水砂层中地下连续墙施工槽壁稳定性及变形研究分析

泥浆护壁是轨道交通车站围护结构地下连续墙成槽质量的关键所在。整体失稳及局部失稳是地下连续墙在富水砂层施工中的主要破坏形式。结合南昌轨道交通3号线柏岗站富水砂层地下连续墙施工实际,采用Plaxis软件建立模型,分析其成槽施工阶段的槽壁变形特征和稳定性,找出南昌地区富水砂层中地下连续墙槽壁变形及地表沉降的规律,印证了施工现场泥浆性能参数及土体应力变化的规律。     

高速铁路隧道接触网槽道施工

高速铁路隧道接触网槽道施工精度要求高、造价高且存在不可修复的特点,因此,高铁接触网槽道施工非常关键。本文对高速铁路接触网的施工工艺及技术控制要点进行了探讨。     

Specification and calibration of a microscopic model for pedestrian dynamic simulation at signalized intersections: A hybrid approach

Macroscopic pedestrian models for bidirectional flow analysis encounter limitations in describing microscopic dynamics at crosswalks. Pedestrian behavior at crosswalks is typically characterized by the evasive effect with conflicting pedestrians and vehicles and the following effect with leading pedestrians. This study proposes a hybrid approach (i.e., route search and social force-based approach) for modeling of pedestrian movement at signalized crosswalks. The key influential factors, i.e., leading pedestrians, conflict with opposite pedestrians, collision avoidance with vehicles, and compromise with traffic lights, are considered. Aerial video data collected at one intersection in Beijing, China were recorded and extracted. A new calibration approach based on a genetic algorithm is proposed that enables optimization of the relative error of pedestrian trajectory in two dimensions, i.e., moving distance and angle. Model validation is conducted by comparison with the observed trajectories in five typical cases of pedestrian crossing with or without conflict between pedestrians and vehicles. The characteristics of pedestrian flow, speed, acceleration, pedestrian-vehicle conflict, and the lane formation phenomenon were compared with those from two competitive models, thus demonstrating the advantage of the proposed model.     

油田流动污水介质中溶解氧对A3钢腐蚀行为的影响

通过腐蚀管流动态模拟装置,模拟现场工艺条件,研究了暴氧和除氧条件下,油田流动污水介质中A3钢的腐蚀行为。用失重法和交流阻抗、极化曲线方法,揭示了A3钢在油田污水介质中腐蚀的电化学规律。结果表明:A3钢在油田污水介质中的腐蚀受阴极氧的去极化控制,流动过程和溶解氧共同作用,极大地加速了油田污水介质对A3钢的腐蚀性。     

基于VC、ANSYS和Access的含缺陷管道安全评定系统

含缺陷管道安全评定技术研究是油气管道施工与生产管理中的一个重要内容。系统分析了油气管道主要力学条件并综合考虑管道表面体积型缺陷等影响因素,利用ANSYS有限元分析软件的二次开发功能,运用VS2005、Access、ANSYS及其APDL语言,开发了含缺陷管道安全评定系统。该系统实现了数据库管理,含任意形貌的外缺陷、内缺陷和凹痕缺陷管道的参数化建模,非线性有限元分析以及安全评定,能够对多条管线全部缺陷的单一分析、组合分析进行全自动批量处理和控制,能够用于在役管线安全评定分析,为含缺陷管线的分析研究提供了有力工具。     

Build-to-order supply chain network design under supply and demand uncertainties

Supply chain disruptions are unintended, unwanted situations resulting in a negative supply chain performance. We study the supply chain network design under supply and demand uncertainty with embedded supply chain disruption mitigation strategies, postponement with downward substitution, centralized stocking and supplier sourcing base. We designed an integrated supply-side, manufacturing and demand-side operations network in such that the total expected operating cost is minimized. We modeled it in a deterministic equivalent formulation. An L-shaped decomposition with an additional decomposition step in the master problem is proposed. The computational results showed that parallel sourcing has a cost advantage against single sourcing under supply disruptions. In addition, the build-to-order (BTO) manufacturing mitigation process has its greatest impact with high variations on demands and is integrated with the component downward substitution. Lastly, the manufacturer needs to order differentiated components to cover its requirement for maximal product demand to prevent the loss of sale, even with fewer modules in stock.     

The role of household members in transporting adults with disabilities in the United States

Because of certain requirements under US federal law, many studies have been published in recent years on the role of fixed-route transit and paratransit in meeting the travel needs of persons with disabilities. Although persons with disabilities are several times more likely to take rides from household members than to take public transit, little research has been conducted to explore the circumstances under which such rides are given or taken. To address this gap in literature, this study examines the role of household members in transporting persons with disabilities in contemporary America. It explores how the circumstances for the ride takers may change in the future, identifies future challenges in providing mobility to persons with disabilities, and examines ways to meet those challenges. Using nationwide data from the 2009 National Household Travel Survey, the study compares the rides taken by persons with disabilities from household members with trips made by other travel modes, the persons who take rides with those who do not take rides, and the drivers who provide rides with those who do not provide rides. Probit models are used for the comparisons. Implications of the findings are discussed in light of potential demographic changes in the future, especially the growth of single-person households and the consequent loss of household support for transportation. Due to similarities in circumstances in other developed countries, an international context to the study is also provided.     

郑西客运专线大断面黄土隧道施工方法研究

文章结合郑西客运专线大断面黄土隧道设计、施工及科研情况,从沉降变形控制、施工进度、机械配套等方面对双侧壁导洞、CRD、CD、弧形导洞等4种工法进行了比选分析,提出了与不同工况相适应的工法以及施工要点,可供参考和借鉴。     

南宁大桥水中主墩基础施工方案优化研究

文章针对广西南宁大桥主桥下部结构初步施工方案,结合现场施工条件,因地制宜地提出了大桥主墩基施工的优化方案,并通过与原施工方案对比及安全论证,验证了该优化方案的合理性。     

The analysis of regulation on private highway investment under a build-operate-transfer scheme

The build-operate-transfer (BOT) approach has become an attractive instrument for public facility provision, especially for a project that faces difficulty with public finance. This study analyzes the regulation alternatives on private highway investment under a BOT scheme and their impacts on traffic flows, travel costs, toll, capacity, and social welfare (total user-benefit in the traffic system including congestion). For comparison, five cases are analyzed: (1) No BOT with maximizing welfare, (2) No BOT with breaking even on finance, (3) BOT without regulation, (4) BOT with a minimum flow constraint (the total users will not be less than those in Case 1), and (5) BOT with a maximum travel cost constraint (the travel cost for users on a non-tolled road will not exceed the maximum tolerance). After each case is modeled and simulated on some functional forms, we find that the case of BOT with regulations performs between the cases of maximizing welfare and that of maximizing profit. From the perspective of the government, regulation has less power in a project with low elastic demand. Furthermore, even when the regulation is strict, a high cost-efficient firm with BOT could result in a higher level of social welfare than that without a BOT scheme.     

复杂环境超小间距隧道盾构掘进施工技术北大核心CSCD

针对浅埋超小间距隧道盾构施工,文章以特拉维夫红线轻轨工程西标段双线盾构施工为工程背景,从隧道加固施工、盾构掘进控制、监测控制与应急管理等方面进行系统研究。结果表明,加固施工在小间距盾构隧道施工中至关重要,可有效降低隧道施工风险;对未加固的小间距盾构隧道施工,应保持土压平稳,加强土压精细化控制;严格控制出渣量,做好渣土改良,控制土体损失率低于0.3%;在盾壳外部注入膨润土或克泥效,可有效地减少邻近隧道的位移量;应结合实时监测数据,控制回填注浆量及注浆质量;隧道施工过程应加强对邻近既有建筑物的监测。     

考虑渗流场与应力场耦合的边坡稳定性分析

文章在介绍渗流问题有限元公式的基础上,运用变单元渗透系数法的原理,利用ANSYS软件的APDL语言开发了二维稳定和非稳定渗流的程序,通过迭代即可较准确地求出自由面的位置;同时,针对某一具体算例,分别对不考虑应力影响下的渗流场和不考虑渗流影响下的应力场以及两场相互耦合时的稳定性进行了研究,为非稳定渗流下边坡稳定分析和滑坡灾害预报等方面提供有用的参考。