公路工程项目风险管理初探

我国公路建设项目前期工作中风险管理是一个比较薄弱的环节，针对此情况，本文就公路工程风险管理的理论和实践问题作了初步探讨，希望通过对公路项目的风险管理，为项目科学决策提供一些依据。     

区域路网新建公路转移交通量预测方法研究

提出一种基于现状路网路段交通量来预测新建公路转移交通量的预测方法。该方法分为3个步骤：确定路段的交通阻抗；找出与新建路有竞争关系的最短路径及次短路径；确定节点之间的出行量、分配并汇总转移交通量。     

高架桥横向地震反应参数分析

建立了高架桥双自由度体系横向地震反应的计算模型以及运动方程,利用解析方法及数值分析方法对城市高架桥结构横向地震反应参数进行了比较分析.阐述了阻尼比、质量比、刚度比以及扰动频率等参数对桥墩振动反应的影响规律.结果表明:主梁与桥墩的质量比对桥墩振动的影响较小,适当增加阻尼比及支座的刚度可以减小桥墩的振动反应.     

Wheel Load Distribution in Simply Supported Concrete Slab Bridges

This paper presents the results of a parametric study related to the wheel load distribution in one-span, simply supported, multilane, reinforced concrete slab bridges. The finite-element method was used to investigate the effect of span length, slab width with and without shoulders, and wheel load conditions on typical bridges. A total of 112 highway bridge case studies were analyzed. It was assumed that the bridges were stand-alone structures carrying one-way traffic. The finite-element analysis (FEA) results of one-, two-, three-, and four-lane bridges are presented in combination with four typical span lengths. Bridges were loaded with highway design truck HS20 placed at critical locations in the longitudinal direction of each lane. Two possible transverse truck positions were considered: (1) Centered loading condition where design trucks are assumed to be traveling in the center of each lane; and (2) edge loading condition where the design trucks are placed close to one edge of the slab with the absolute minimum spacing between adjacent trucks. FEA results for bridges subjected to edge loading showed that the AASHTO standard specifications procedure overestimates the bending moment by 30% for one lane and a span length less than 7.5 m (25 ft) but agrees with FEA bending moments for longer spans. The AASHTO bending moment gave results similar to those of the FEA when considering two or more lanes and a span length less than 10.5 m (35 ft). However, as the span length increases, AASHTO underestimates the FEA bending moment by 15 to 30%. It was shown that the presence of shoulders on both sides of the bridge increases the load-carrying capacity of the bridge due to the increase in slab width. An extreme loading scenario was created by introducing a disabled truck near the edge in addition to design trucks in other lanes placed as close as possible to the disabled truck. For this extreme loading condition, AASHTO procedure gave similar results to the FEA longitudinal bending moments for spans up to 7.5 m (25 ft) and underestimated the FEA (20 to 40%) for spans between 9 and 16.5 m (30 and 55 ft), regardless of the number of lanes. The new AASHTO load and resistance factor design (LRFD) bridge design specifications overestimate the bending moments for normal traffic on bridges. However, LRFD procedure gives results similar to those of the FEA edge+truck loading condition. Furthermore, the FEA results showed that edge beams must be considered in multilane slab bridges with a span length ranging between 6 and 16.5 m (20 and 55 ft). This paper will assist bridge engineers in performing realistic designs of simply supported, multilane, reinforced concrete slab bridges as well as evaluating the load-carrying capacity of existing highway bridges.     

Strategic Interactions of Bilateral Monopoly on a Private Highway

This paper investigates strategic interactions between a private highway operator and a private transit operator who uses the same highway for its services. Heterogeneity of travellers is taken into account by considering a continuous distribution of values of time. Demand elasticity arises from the inclusion of an outside virtual mode. Game theory is applied to model the possible moves taken by the operators in their interactions. Four games are formulated, representing different decision making processes, including Nash and Stackelberg (leader-follower) games. The different timings of long-run and short-run decisions are also modeled in a two-stage game. Our results indicate that the market equilibria in the four games formulated are quite different as a result of the different sequences of moves. The highway operator is considered to be in a better position in terms of profit making in most cases, while for the transit operator it will generally be more advantageous to be the follower rather than in the leader position.     

基于个体信息需求的草原公路防疲劳预警策略

为缓解驾驶人在草原公路行驶产生的驾驶疲劳,设计一种基于个体信息需求的防疲劳预警策略,采用问卷调查将驾驶人划分成视觉型、听觉型和触觉型3类,综合考虑不同类型驾驶人的个性化信息需求,设计路端预警、车端预警和车端路端协同预警3种草原公路驾驶疲劳预警策略,选取21名驾驶人开展驾驶模拟实验,采集驾驶人KSS量表数据、对预警策略的主观评价数据和驾驶行为数据,利用描述性分析、统计分析和基于熵权的TOPSIS综合分析等方法,进行3种驾驶疲劳预警策略的效果测试。结果表明:驾驶人对3种预警策略的接受程度均较高;3种驾驶疲劳预警策略均可以不同程度地缓解驾驶疲劳状态,协同预警策略优于其他两种策略,且疲劳程度越深,缓解效果越显著。基于驾驶人差异化信息需求的车端路端协同防疲劳预警策略有助于提升草原公路驾驶疲劳预防效果。     

基于改进BP网络模型的公路流量预测

针对公路客货运量预测的问题,对现有的常用预测方法进行研究,提出改进BP神经网络预测模型。该模型首先采用动态陡度因子改变激励函数的陡峭程度,改善激励函数的响应特征,得到更好的非线性表达能力;其次利用附加动量因子,通过将以前的经验进行积累,降低了神经网络对误差曲面的局部细节敏感性,较好地遏制网络陷于局部最小;再次采取变学习率学习算法,先给一个较大初值,随着学习过程的进行,学习率不断减小,网络趋于稳定。改进BP算法既可以找到更优解,又可以缩短训练时间。结合某地区的公路运量相关数据,对改进BP神经网络预测模型进行了验证。实验结果表明,该模型的相对误差和迭代次数都取得了较大的改善,对公路客货运量预测很有效。     

基于车载GNSS数据的公路测绘及事故多发路段分析

采用车载GPS系统对某公路路段的平面坐标数据进行测绘与数据采集,使用专家打分法对公路环境与事故进行关联性分析,并关联坐标方位角与事故发生之间的关系。结果表明,采用车载GPS系统可以对公路路段信息进行有效采集,包括平面坐标数据和计算坐标方位角; K65～K67公路直线段和曲线段事故次数平均值分别为11次和32次,曲线段事故平均次数约为直线段事故次数的3倍。专家评分结果与事故次数之间具有较高的关联性,即专家评分较高的路段,事故次数较少,而专家评分较低的路段,事故次数较多;公路线形对公路交通事故的影响与专家评分结果相吻合。     

高速公路工程水土流失预测与分析实践

为验证《生产建设项目土壤流失量测算导则》(简称《导则》)对高速公路工程的适用性,运用《导则》对西南地区某高速公路工程建设进行水土流失预测,并与类比法测算结果进行对比.测算结果表明,路基工程区、附属设施区和弃渣场区是该项目土壤流失最多的区域,大部分土壤流失发生在施工期;采用《导则》与类比法得到的土壤流失量测算结果差异主要...     

湿陷性黄土地区公路排水及病害防治对策探索

黄土地区公路工程施工建设中,需要关注黄土的特性,对路基做好有效处理,以保证工程整体施工质量和使用安全.面对湿陷性黄土时,必须切实做好公路排水设施的设计和施工及日常性养护,对常见病害进行防治,尽可能将湿陷性黄土对公路工程质量的影响降到最低.本文结合湿陷性黄土的特征,对公路排水工程中的常见病害及防治对策进行了分析.