互通式立交匝道“急转弯”线形安全设计研究

匝道"急转弯"线形是互通式立交中常出现而又存在安全隐患的部分,该文研究了目前国内互通式立交在其设计方面存在的不足,提出了改善其安全性的"急转弯"线形设计方法。     

浅析宝成铁路109号隧道震后改线方案的合理性

该文根据宝成铁路109隧道所处的地形地貌、工程地质及水位条件,通过五个线路方案的比较,从线路技术条件、工程地质水文条件、抢险工期、施工条件等方面分析论证,确定改线方案的合理性。     

Vehicle steering returnability with maximum steering wheel angle at low speeds

In this paper, an analytical model with suitable vehicle parameters, together with a multi-body model is proposed to predict steering returnability in low-speed cornering with what is expected to be adequate precision as the steering wheel moves from lock to lock. This model shows how the steering response can be interpreted in terms of vertical force, lateral force with aligning moment, and longitudinal force. The simulation results show that vertical steering rack forces increase in the restoring direction according to steering rack displacement for both the inner and outer wheels. As lateral forces due to side-slip angle are directed toward the medial plane of the vehicle in both wheels, the outer wheel pushes the steering wheel in the returning direction while the inner wheel does not. In order to improve steering returnability, it is possible to increase the total steering rack force in both road wheels through adjustments to the kingpin axis and steering angle. This approach is useful for setting up a proper suspension geometry during conceptual chassis design.     

Applicability of highway alignment optimization models

This paper presents an intelligent optimization tool that assists planners and designers in finding preferable highway alignments, connecting specified endpoints or zones. It integrates genetic algorithms with a geographic information system (GIS) for optimizing highway alignments and processes massive amounts of relevant data associated with highway design and alternative evaluation. To show the applicability of the proposed model to a real-world problem, two actual highway projects in the state of Maryland have been analyzed using the model. An extensive analysis of sensitivity to key model parameters is also conducted to describe the model capabilities. The analysis results show that the model can effectively optimize highway alignments in an area combining complex terrain and various types of natural and cultural land-use patterns, and provide detailed information of optimized alignments as a model output. It is also found that the alignments optimized by the model are quite similar to those obtained through conventional manual methods by a state agency, but the model can greatly reduce the time required for highway planning and design as well as produce lower cost solutions. Finally, the results confirm that all dominating and alignment-sensitive costs should be simultaneously evaluated in the alignment optimization process because many trade-off opportunities exist among those costs. The proposed model can greatly contribute to the productivity of highway planners as well as to the quality of the resulting infrastructure.     

船舶轴系校中有限元法研究及软件开发

轴系校中有限元法是一种计算精度较高的方法,本文介绍了有限元法的基本理论,并用Visual C 编写了相应的计算软件,并运用该软件对某船进行了计算,与国外软件计算的相应结果做了比较,可以看到本方法的计算精度较高、结果可靠.     

双车道公路线形连续性及舒适性评价研究

针对公路线形连续是保证汽车安全行驶的基本要求,提出相邻路段运行车速相协调的路线设计理念,并提出双车道公路线形连续性评价标准,旨在为设计和改建双车道公路提供重要依据,提高线形设计质量,减少交通事故。经实例分析证实所提标准较为合理,并根据分析结果,讨论并提出了相应的改善措施。此外,从驾驶员的角度对线形的舒适性做出了评价,并提出双车道公路线形舒适性的评价标准,更加体现了"以人为本的交通理念"。     

铁路电分相布设及纵断面协同优化研究

铁路电分相布设位置与线路纵断面设计相互影响，两者若不匹配会产生较高的列车牵引能耗与用户时间成本，甚至造成列车在分相区坡停等安全事故。本文以铁路电分相位置以及距离电分相中心里程一定范围内的纵断面设计方案为研究对象，建立电分相布设及纵断面设计协同优化模型，在满足铁路设计规范与列车运行安全的相关约束下，使列车运营能耗成本、用户时间成本和建设成本之和最小。设计基于间接编码的改进遗传算法进行求解，以某高铁线路为案例进行分析。结果表明，与实际电分相和纵断面布设方案相比，本文模型优化得到的方案可减小列车过分相后的速度损失及二次牵引能耗与时间，同时能降低线路建设成本，总成本节约率达 9.2%。     

基于驾驶负荷的山区二级公路纵坡路段驾驶舒适度评价研究

为定量评价山区公路纵坡路段驾驶舒适度，本文以云南省文都二级公路为研究对象，进行实车试验开展驾驶负荷研究.首先，分析上、下坡路段坡度、坡长、加(减)速度指标对驾驶负荷影响程度，运用多元回归建立驾驶负荷模型；其次，利用心率增长率的第50、85分位值划分驾驶舒适度，结合所建模型对驾驶舒适度进行阈值分析，确定不同驾驶舒适程度对应坡度、加(减)速度区间范围；最后，对模型及阈值划分合理性进行分析验证.结果表明，坡度、加 (减)速度对纵坡路段驾驶负荷皆为显著变量，而坡长与驾驶负荷仅存在弱相关性.本文模型有效，阈值划分合理，可为低等级公路驾驶负荷研究提供参考.     

山区高速公路隧道交通安全研究

随着隧道的较广泛应用,隧道交通安全问题日益突出。研究山区高速公路隧道安全问题,建立安全审核清单以主动防御和减少交通事故,为提高隧道的运营安全性提供了理论和技术支持,具有重要的应用价值。本文研究了山区高速公路隧道安全问题,建立了安全评价清单,并针对隧道安全问题提出了改善措施。     

犍为岷江大桥加固施工监控设计与实践

施工监控是桥梁建设及加固改造工程中必不可少的一部分.文章结合犍为岷江大桥加固施工工程,对其监控方案进行了介绍,通过各施工阶段现场测试和结构计算分析,从线形控制、变形监测与应力监测等方面阐述了施工监控技术及效果,以供桥梁施工技术人员参考.