浅谈高速公路桥头跳车的因素及预防措施

桥头跳车一直是高速公路投入使用后普遍存在的问题,本文通过查阅各种资料及本人施工经验,归纳总结了桥头跳车问题产生的原因,提出了桥头跳车问题的预防措施,以便为今后类似工程的施工提供参考。     

A stochastic optimization approach for the selection of reflective cracking mitigation techniques

PurposeIn Hot Mix Asphalt (HMA) overlays, the existing cracks in the underlying pavements can propagate upward to the new added overlay and may cause Reflective Cracks (RC). These cracks allow water infiltration to the underlying layers and causes further moisture damage as well as weakening the unbound layers. Over the years, several methods have been developed for mitigating the RCs. This study aims to investigate the current reflective cracking mitigation methods and develop a methodology for the selection of appropriate mitigation technique. The developed model is then applied to a case study in the state of Florida.MethodTo accomplish this goal, a nationwide literature review was conducted to better understand the current in practice methods in the United States. Moreover, a life cycle cost analysis (LCCA) in five different road types was performed to find the annuity of roadway rehabilitation for each of the mitigation methods. The uncertainty in the LCCA results is represented using Exploratory Modeling and Analysis (EMA) method. Then through a Multi Criteria Decision Making (MCDM) model, a stochastic optimization model was developed to find the appropriate reflective cracking mitigation solution under Florida’s climate and road conditions, based on different cost and performance weights.ResultsBased on the available data for the state of Florida, the LCCA results indicate that the annuity of maintaining the roadway with Fabrics and ISAC are lower compared to other methods. However, the results of stochastic optimization model reveal that while looking at the performance and cost at the same time, different methods would be more feasible. For instance, while the cost of the used method does not matter at all and only performance matters, STRATA® is more probable to be the appropriate mitigation technique. The findings of this research are critical for decision makers to better understand the most cost-effective mitigation technique in different conditions.     

有限元分析在12m标准轨道衡承重梁设计中的应用

在12 m标准轨道衡承重梁设计过程中采用有限元分析,利用Ansys建立承重梁的几何模型和以壳单元shell63为基本单元的承重梁有限元计算模型。计算模型在不同载荷作用下的最大应力以及变形情况,提出在不改变主体结构的情况下对承重梁进行加固。此方法可为12 m标准轨道衡承重梁的结构设计和改进提供理论依据。     

铁路建设物资汽车运输单价探讨

铁路建设工程投资主要由工料机费用、运输费及其他相关费用组成。运输方面的费用通常占静态投资的3％-10％，而采用汽车运输物资的费用占到总运输费用的65％～90％。为此，合理确定建设项目汽车运输物资的单价就显得格外重要。此文结合有关计算汽车运输单价的规定和执行情况及存在的主要问题，分析影响汽车运输单价的因素。并采用既有概预算编制办法的有关规定测算汽车运输单价，与采用自卸汽车运输和路基运输定额测算的汽车运输单价进行比较分析，研究其影响因素和运价率的一般规律。提出合理确定汽车运输单价的建议。     

合理拱轴线确定方法探讨

从悬索结构与具有合理拱轴线的拱结构受力相似的角度出发，将悬索结构在荷栽作用下的线形沿水平面镜像后作为拱结构的压力线．以5次多项式拟合该压力线．从而确定出受力合理的拱轴线。     

某轻型客车采暖的理论分析与试验

为适应客户不断提高的乘坐舒适性,汽车空调设计开发也在不断提高自身水平,以满足市场需要。原有的空调设计、试验、整改、再验证的手段已经逐渐不能适应产品开发周期。空调的设计开发需要依靠一定的理论计算,为系统匹配、及整改方案提供理论依据。本文通过使用建立的理论分析模型,定性的、定量的对某轻型客车采暖性能问题进行分析,并提出整改验证,试验证明本文的理论分析模型方向是正确的。     

基于最优理论的CVT多片湿式离合器片间压力的确定

利用最优理论和方法,结合湿式离合器的特点,提出无级变速器湿式离合器接合过程中摩擦片间最佳压力的确定方法。仿真结果表明,相对于基于线性压力的控制方法,基于最优理论确定的摩擦片间压力能较好的解决无级变速器湿式离合器接合过程中滑磨功和冲击度之间的矛盾,实现了汽车的平稳快速起步。     

百色-罗村口高速公路高填方路堤稳定性分析

文章结合广西百色-罗村口高速公路段高填路堤段路面出现20多处纵向直线形张开裂缝情况,分析路基稳定性及路面开裂形成机理,介绍利用边坡稳定分析计算软件以及圆弧滑动法对路基的稳定性进行计算的方法,并对路堤综合整治提出了相关的建议。     

变速比转向器齿轮副的机理分析

本文运用啮合原理分析方法给出了变速比转向器齿条齿扇传动的啮合线方程、齿扇的齿廓方程,导出了锥形齿扇被切削时小端不根切、大端不尖的变位系数和齿扇几何尺寸计算公式。     

电控汽油喷射系统控制特性的探讨

简述了电控汽油喷射系统的优点，介绍了电控汽油喷射系统的两种主要控制方式。对冷起动与起动后供油增量特怀，暖车供油增量特性电压修理特性等９种汽油喷射系统的控制特性 探讨，分析了具体工作过程。