沥青混合料拉压疲劳损伤试验

为研究沥青路面结构实际处于拉压应力作用下的疲劳损伤特性,针对沥青混合料AC-13开展了连续式交变正弦波形加载的小梁拉压疲劳试验。依据损伤力学基本理论,采用唯象学方法分析了沥青混合料的拉压疲劳损伤特性。介绍了拉压疲劳试验方法及影响因素,根据疲劳试验结果得到了拉压疲劳方程;基于弹性模量定义的损伤变量,建立了拉压疲劳损伤模型,拟合疲劳试验结果确定了损伤参数,获得了考虑应力水平的拉压疲劳损伤演化方程。研究结果表明:疲劳损伤参数α、β随应力水平增大而增大,且近似呈线性关系;拉压疲劳损伤演化大致呈3阶段变化规律,即损伤萌生、损伤稳定增长和损伤失稳破坏阶段;应力水平越大的损伤演化曲线越靠下,随寿命比变化疲劳损伤演化速度越缓和。     

旧水泥路面碎石化加铺级配碎石与沥青罩面结构组合设计参数研究

结合工程实际,针对旧水泥路面碎石化加铺级配碎石与沥青罩面结构,利用有限元计算方法量化分析了不同级配碎石层厚度及模量、沥青罩面层厚度对罩面结构的变形及力学性能影响,确定了该罩面结构组合设计参数的合理取值范围,可为旧水泥路面碎石化加铺级配碎石与沥青罩面结构组合设计提供参考。     

水泥砼路面脱空检测与灌浆治理

随着交通事业的发展,公路路面的病害也逐渐暴露出来。主要针对混凝土路面下出现的板底脱空,提出了采用车载弯沉仪与探地雷达相结合的方法,探测板底脱空部位及板底路基病害,并对混凝土路面板底脱空灌浆处理后的效果进行评价。     

NKY桥面防水粘结层在水泥混凝土桥面中的应用

NKY桥面防水粘结层属于新材料,该材料抗剪切和拉拔力学性能良好,喷洒后能快速干燥,无需撒布碎石,施工方便,经济效益明显,对水泥混凝土桥面防水粘结层技术的完善,减少桥面病害,具有重要的现实意义和工程实用价值。     

沥青稳定碎石下面层（ATB-25）矿料级配研究

设计了5种连续级配的沥青稳定碎石配合比,并采大马歇尔试验对混合料性能进行检测,结果表明空隙率和饱和度在确定沥青稳定碎石混合料最佳沥青用量时起主要作用;不同级配对混合料的各项性能均有一定的影响．在进行配合比设计时要找出最佳级配曲线。     

突起路标逆反射器自动冲击装置的研制及应用

本文主要描述了一种用于检测突起路标逆反射器抗冲击性自动试验装置,包括冲击装置和试样保持架,解决了目前突起路标逆反射器抗冲击试验过程中的装置简陋或部分缺失、操作不规范、试验结果不准确及存在安全隐患等问题,符合实际生产的需求,提高了实验效率,准确有效的测量了突起路标的逆反射器抗冲击性能,确保了产品性能检测指标。     

西南某机场水泥混凝土道面板应力计算分析

为了对西南某机场水泥混凝土道面板进行应力分析,通过现场钻芯取样和劈裂实验得出劈裂强度值和基层顶面反应模量。应用ANSYS软件建立三维有限元模型,计算不同飞机荷载作用下的板边应力。由应力折减系数得出板边计算应力,判断道面能够运行的最大飞机重量。比较板边自由与不自由两种状态下道面产生的应力和位移,发现高温作用下道面的受力变化与低温状态下不同,对机场道面在夏季和冬季运行时提出建议。     

Multi-objective optimization for asphalt pavement maintenance plans at project level: Integrating performance,cost and environment

Traditionally, asphalt pavement maintenance mainly considers pavement performance and cost and largely ignores the environment while substantial amount of environmental burdens are released in the process. In this study, a multi-objective optimization model was developed integrating the three elements in order to optimize the asphalt pavement maintenance plans at the project level. Pavement performance element was decided as the multiplier of pavement serviceability index and traffic volume. Cost element was represented by the net present value, including components of agency cost, vehicle operation cost and salvage value. Environmental element, integrating energy consumption, global warming potential, acidification potential and respiratory effects potential, was measured by the life cycle assessment model. A hypothetic asphalt pavement maintenance case study was conducted using the developed multi-objective optimization model and harvested 103 sets of feasible combinations of maintenance plans, each of which is non-dominated by the others. Trade-offs analysis was performed among the three objectives and visualized in both two- and three-dimension forms. It is found there is an opportunity of reducing the cost and environmental impacts to 80.3% and 77.8% and increasing the pavement performance to 146.6% compared to the base case. However, they are mutually compromised and cannot be reached simultaneously. The developed model reveals the quantitatively interactive relationship of the three objectives and helps optimize the asphalt pavement maintenance plans.     

Do people drive safer when accidents are more expensive: Testing for moral hazard in experience rating schemes

Using individual policies and claims data from the Croatian mandatory motor insurance we test the theoretical proposition that under moral hazard, experience rated pricing scheme should generate the negative state dependence in claims, i.e. that drivers should drive more safely after they had an accident. The empirical challenge in these tests is to disentangle the state dependence from unobserved heterogeneity. We propose a simple approach based on the explicit reliance on the cost of future accidents function which is used to filter out the pure incentives effect, whereas the bonus-malus scale is used to control for pure heterogeneity. Our results confirm the existence of negative dependence in claims indicating the presence of significant moral hazard effect. Increasing a 3-year cost of having an accident by approximately US$20 decreases the probability of having an accident by 6.5%.     

Environmentally appraising different pavement and construction scenarios: A comparative analysis for a typical local road

The aim of this work is to carry out a comparative analysis of environmental impacts for different scenarios of a typical local road. Life Cycle Assessment (LCA) is the modeling tool used to quantify and characterize comparative environmental impacts. In carrying out this specific application of the LCA, different road construction techniques were considered with regards to the whole structure and compared in order to identify the best alternative in terms of environmental sustainability.So far, in fact, typical LCA frameworks of roads have focused on recycled materials for pavement layers only, thus neglecting study of the materials used in the embankment or in the subgrade. In this study, these materials were included too, in order to prove the environmental benefit of using a sustainable technique such as in situ stabilization of fine soils with lime (typically dumped clayey soils) in order to reduce the need for virgin material for embankment and subgrade construction.When using different percentages of recycled materials (such as reclaimed asphalt pavement – RAP) in the bituminous layer or in the foundation, the analysis of the functional unit studied shows a significant reduction of energy consumption and pollutant emissions mainly due to transportation of materials involved, in this way increasing the environmental performance of the road.Another important consideration is that the use of fine soils stabilized with lime “in situ”, instead of dumping it, not only is a good technical solution for improving soil mechanical properties, but it also produces a reduction of energy consumption and of pollutant emissions. It is noticeable that this technique results in a significant reduction of pollutant emissions due the transportation of involved materials, increasing the environmental performance of the road.