库水位变化对路基边坡稳定性的影响研究

在渗流计算理论与极限平衡方法的基础上,对库水位升降作用下路基边坡的瞬态渗流场与稳定性进行数值模拟与研究。研究结果表明：1）在库水位上升过程中,浸润线位置几乎与库水位的变化“同步”,只存在短时间的“滞后”效应;而在库水位下降过程中,滑坡体内浸润线位置严重滞后于库水位的变化。2）库水位上升期间,路基边坡孔隙水压力增加,安全系数增加,最高库水位（175m）持续期,路基边坡孔隙水压力增加,安全系数缓慢降低;库水位下降期间,路基边坡孔隙水压力降低,安全系数迅速降低,最低库水位（145m）持续期,路基边坡孔隙水压力降低。安全系数缓慢增加。     

高速公路景观安全协调性研究

采用加权区间层次分析法和模糊数学法对高速公路景观安全协调性进行分析,将高速公路景观设计安全评价细分为线形、中央分隔带、路侧、桥梁、隧道、交叉口、服务区、附属设施等8个评价要素,分项提取和建立各自的评价指标体系,定量评价其景观安全协调性的优劣程度,以重庆涪陵至石柱沿江高速公路的景观安全协调性研究为例对该指标体系进行验证。结果表明加权区间层次分析法有效可行,简洁易实现,具有较好的现实意义。     

既有混凝土梁桥抗震性能评价

针对既有混凝土梁桥抗震性能评价尚无规范可循的现状,结合正在实行的《公路桥梁抗震设计细则》（JTG／T B02－01－2008）以及《公路桥梁抗震性能评价细则》（征求意见稿）,对相关规定对比分析,明确既有混凝土梁桥抗震性能评价方法。根据桥梁的重要程度、建造年代、设计标准等确定抗震性能目标;对桥梁进行调研,针对构造措施、构造细节等进行一级评价;对关键构件进行详细的抗震能力评价,依据结构形式、材料实际强度等,对其整体抗震性能进行二级评价;综合评价结果,针对存在的问题提出解决建议。将该方法应用于京沪高速公路某混凝土梁桥,得出该桥总体抗震性能不满足要求,建议优化支座布置方式及更改支座型号,或采取减隔震措施。应用实例验证该评价方法思路清晰、步骤明确、便于应用。     

Research on the relationship among subgrade bearing capacity,embankment stability and settlementEI北大核心

Research purposes: In order to ensure the safety of railway or highway subgrade, subgrade bearing capacity, embankment stability and settlement which are the three main control indexes of subgrade design should be analyzed and checked in theory. However, many railway and highway designers still have differences on whether subgrade bearing capacity should be calculated in our country. Through analyzing the relationship among subgrade bearing capacity, embankment stability and settlement, the necessity of checking subgrade bearing capacity is discussed in this paper. Research conclusions: (1) It is unsafe that circular arc method is used to check the embankment stability, in the case that subgrade bearing capacity does not meet the requirements, the conclusion that embankment is stable can be also drawn. (2) The lateral displacement of subgrade will increase sharply when the load approaches or exceeds subgrade ultimate load, and the existing settlement calculation methods are no longer applicable. The application condition of settlement calculation methods is that the requirement of subgrade bearing capacity is met. (3) In order to ensure the stability of the embankment and control the settlement of it, the subgrade bearing capacity should be checked in the design of subgrade. (4) In this paper, the research conclusion can provide a theoretical basis for the further improvement of subgrade design method.     

Optimal transit fare in a bimodal network under demand uncertainty and bounded rationality

This paper investigates the optimal transit fare in a simple bimodal transportation system that comprises public transport and private car. We consider two new factors: demand uncertainty and bounded rationality. With demand uncertainty, travelers are assumed to consider both the mean travel cost and travel cost variability in their mode choice decision. Under bounded rationality, travelers do not necessarily choose the travel mode of which perceived travel cost is absolutely lower than the one of the other mode. To determine the optimal transit fare, a bi‐level programming is proposed. The upper‐level objective function is to minimize the mean of total travel cost, whereas the lower‐level programming adopts the logit‐based model to describe users' mode choice behaviors. Then a heuristic algorithm based on a sensitivity analysis approach is designed to solve the bi‐level programming. Numerical examples are presented to illustrate the effect of demand uncertainty and bounded rationality on the modal share, optimal transit fare and system performance. Copyright © 2013 John Wiley & Sons, Ltd.     

城市商业步行街服务水平评价体系研究

从量化的角度对城市商业步行街的服务水平进行分析。以西安市2条典型商业步行街为例,对断面情况、行人特性、障碍物、步行街相关设施以及其它影响因素进行问卷调查,借助SPSS软件筛选出主要影响因素,建立商业步行街服务水平评价模型,并通过模型对商业街服务水平进行计算,模型的计算结果与实际调研结果相吻合。     

全球海上遇险与安全系统复审与现代化研究

国际海事组织（IMO）海上安全委员会第九十次会议批准的＂全球海上遇险与安全系统（GMDSS）复审和现代化＂项目将于2017年完成。本文回顾了上世纪九十年代海上通信的变革;指出了GMDSS实施的意义和GMDSS复审的必要性;研究了国际海事组织正在进行的GMDSS复审和现代化计划及成果;提出了GMDSS高级复审和详细复审的内容和领域。     

中小城市公共交通评价指标体系研究

我国一直以来缺乏针对中小城市公共交通的评价指标体系来引导其公共交通发展。从公交基础设施建设水平和服务水平两方面选取适合中小城市的评价指标,建立起中小城市公共交通评价指标体系,从线网、场站建设和车辆配置3个方面来评价公交基础设施建设水平,从安全、方便、经济、迅速、准确、舒适6个方向来对公共交通的服务水平进行评价,并提出了相应的适合中小城市的指标建议值。     

北京市快速路可靠性分析及应用

快速路作为城市交通网络的重要组成部分,其速度的可靠性直接影响整个城市交通系统运行效率的高低。为了更好地分析快速路的速度特征,选取具有代表性的几条快速路进行了速度可靠性分析。应用SPSS统计软件,对快速路基本路段车辆速度进行了分断面和分时段的研究;通过对各快速路断面和时段的对比分析,得出各条快速路速度可靠性的高低和对应的服务水平,以及城市中向外辐射方向的快速路服务水平高,起联络线作用的快速路部分路段速度可靠性低,车辆在行驶过程中受到的干扰大,快速路应有功能没有得到充分发挥的结论。     

基于短期验潮资料的新建港区设计潮位确定方法*

在沿海港口工程中,确定设计潮位是一项重要的基础工作。对于新建港区,往往只有短期验潮资料,需要借助附近主港的长期验潮资料,采用短期同步差比法和相关分析法计算设计高、低水位,采用相关分析法和K值法计算极端高、低水位。研究判断潮汐性质相似性的定量指标以及基于多个计算结果的设计潮位确定方法。该方法应用于皮口港区总体规划中,为新建港区设计潮位的确定提供了参考。