Guidelines for the use of accelerated pavement testing data in autonomous vehicle infrastructure research

There is much research conducted on the vehicle technologies required for operation of autonomous vehicles(AV) on public roads, as well as analysis of the interaction between AV and the road environment. However, limited research exists on the impact of AV on road pavement structures. The research includes issues such as the effect of more channelized traffic loading, shorter inter-vehicle following distances and potential higher traffic volumes of more uniform vehicle types and loads. This paper discusses the application of existing and generation of new, relevant accelerated pavement testing(APT) data in understanding the effects of AV on pavement infrastructure. The paper presents development of provisional guidelines for the use and application of APT data to ensure that road pavement structures cope with anticipated increase in AV use. It is concludes that the use of AV fleets on existing road pavement infrastructure may lead to different behaviors and responses than what became the norm under non-autonomous vehicle fleets;appropriate analysis of existing APT data will contribute to the improved understanding of these expected changes in behaviors and responses; appropriate planning of AV operations-focused APT is possible with existing technology to contribute to the provision of economic and durable road pavement infrastructure in future.

The Application of Impact Echo Scanning on Nondestructive Test of Pavement

A new nondestructive test method-Impact Echo Scanning was introduced. Application of this method on pavement structure test was discussed. A method to increase the measurement accuracy of the test on multi-layers was proposed, and was verified by field test. The test results show that the basic structural information can obtained rapidly and accurately by 3-D scanning of the impact echo system.

路基路面试验装置伺服加载系统设计及分析

【目标】针对现有路基路面力学性能检测在加载时存在加载荷载单一、加载精度不足等问题,提出了采用电液伺服加载方法的加载系统,应用于路基路面试验装置。【方法】首先,根据实际工程情况,对电液伺服加载系统各组成进行设计,根据系统工作机理及系统元件工作特性建立系统传递函数数学模型。其次,采用比例积分微分控制作为系统控制方法,并对系统数学模型进行仿真。然后,搭建路基路面试验装置电液伺服加载系统,并进行动、静态加载试验。最后,为提高系统控制精度,提出自抗扰控制应用于加载系统,通过把系统3阶及以上阶数视为总扰动一部分,从而对系统进行了降阶处理,采用扩张状态观测器对系统状态及总扰动进行观测,并进行了仿真验证。【数据】所设计电液伺服加载系统满足动态加载最大频率15 Hz的加载要求,在动、静态加载时,输出最大误差和平均绝对误差均小于0.5 kN,且不存在超调现象,但输出最大误差接近0.5 kN情况较多;【结果】在采用自抗扰控制后,加载系统在准确性上有较大提升,系统控制性能得到优化。【应用】采用电液伺服加载系统作为路基路面力学性能检测荷载发生装置,可更全面、更精准地模拟路基路面实际受力状况,有利于路基路面力学性能检测的进一步研究。

盾构渣土免烧路面砖的制备与性能试验研究

土压平衡盾构渣土存在含水率和含泥率较高、产生量大、资源化利用难度大等问题。现有的固化处理方法存在强度低、耐久性差等问题,以盾构渣土为对象,引入碱激发高炉矿渣胶凝材料与技术,设计并发明了一种盾构渣土免烧路面砖。将2mm以下细粒盾构渣土和高炉矿渣混合料作为底层物料,筛分出的碎石、砂以及钢渣作为面层物料,采用单向压制成型法分别将底层和面层物料压制成型,制备得到免烧路面砖成品。试验结果表明:路面砖经自然养护28d抗压强度达51.8MPa,抗折强度为9.1MPa,磨坑长度为22mm, 25次冻融循环后的抗压强度为46.4MPa。相较于现有的技术,本研究具有免烧结、免水泥添加以及优异的力学性能、耐久性能和耐磨性能。路面砖底层与面层厚度比5∶1的双层复合设计不影响路面砖整体性能,相关指标完全满足混凝土路面砖的标准要求,具有较好的应用前景。

流体集热沥青路面温度特性及对城市地表环境温度的影响

【目标】道路沥青路面太阳能集热技术对太阳能的开发利用、路面可持续发展和改善城市热岛效应具有积极的意义,因此开展了流体集热沥青路面对路表温度和显热释放量影响的研究。【方法】首先,构建了流体集热沥青路面模型,分析了太阳能流体集热系统在不同运行条件下的沥青路面温度场;然后,开发了耦合城市峡谷的三维瞬态数值模型,并通过室内试验对模型正确性进行验证;最后,通过开发的模型模拟了太阳能流体集热沥青路面在不同季节的运行性能和对周围环境的影响。【数据】太阳能流体集热沥青路面在春季、夏季、秋季的最高路面温度分别降低了14,20,12℃;应用太阳能流体集热系统的城市路面可以在春季、夏季、秋季、冬季将路面表面的显热释放量分别减少47.41%,60.37%,52.46%,48.62%,虽然夏季热能输出最大,但降低幅度也最大;在夏季,太阳能集热系统可将路面上方1.5 m处的空气温度降低约1.1℃。【结论】太阳能流体集热路面温度在不同季节均小于普通沥青路面;在城市峡谷内,太阳能流体集热系统在夏季收集的热量最多,但集热效率最低。【应用】太阳能流体集热沥青路面为太阳能的开发利用、路面可持续发展和缓解城市热岛效应提供了一种可行且有效的技术路径,具有广泛的应用前景。

沥青路面永久变形特性的数值模拟分析

为探究长期使用过程中沥青路面变形特性,采用有限元数值模拟软件建立路面结构模型,基于黏弹塑性本构关系对不同工况下路面车辙试验进行模拟,探究了加载时间、加载次数、环境温度、胎压等多方面因素对沥青路面形变的影响。结果表明:(1)循环加载下,沥青路面变形速率随时间增加逐渐加快。(2)不同加载次数下沥青路面沿道路横断面(指垂直车辆行驶方向x轴向)的变形均呈“W”形,且随循环加载次数的增多,路面变形深度也逐渐增大,沿车辆行驶方向(y轴向)的变形主要发生在沥青面层。(3)环境温度及胎压对沥青路面永久变形都具有重要影响,路面变形深度均随温度及胎压的增加而增大。

泡沫沥青冷再生路面性能衰减规律

跟踪检测调查路段9年内泡沫沥青冷再生路面损坏PCI、路面车辙RDI、道路平整度RQI、路面结构强度PSSI,分析在役泡沫沥青冷再生路面服役期间技术状况衰减规律。结果表明:服役9年,在承受4928万次标准轴载累计当量轴次后,泡沫沥青冷再生路面的PCI、RDI、RQI、PSSI均评定为优,服役期间泡沫沥青冷再生路面结构弯沉几乎没有衰减,路面未产生结构性车辙,轮迹处车辙深度小于10 mm,泡沫沥青冷再生路面具有优异的使用性能与良好的服务水平,符合长寿命沥青路面特征。

不同压实作用对泡沫沥青冷再生混合料宏细观性能的影响

基于力学性能试验(劈裂强度试验、无侧限抗压强度试验、动态回弹模量试验、贯入剪切试验)和疲劳性能试验,分析现场“二次热压实”作用对泡沫沥青冷再生混合料力学性能及疲劳性能的增强效果,基于工业CT无损检测技术,探讨现场压实和“二次热压实”作用对泡沫沥青冷再生混合料微细观空隙结构的影响规律。结果表明:泡沫沥青冷再生混合料配合比设计阶段采用马歇尔成型方式制备试件,低估了其力学性能与疲劳特性;现场压实及二次热压实后空隙率减小、密实度提高、微细观空隙直径减小,建议实际施工配合比设计阶段增加泡沫沥青冷再生二次热压实。

Rubblization: A Practical, Cost Effective and Sustainable Option for Repairing Deteriorated Airfield Pavement in the Empty Quarter Desert of Saudi Arabia

Rubblization technique has been extensively used to repair the damaged concrete pavement and has proven successful in developed countries like the US and Europe. It has not been fully adopted in developing region like the Middle East and this paper presents the design and construction challenges posed while assessing damaged concrete runway in empty quarter of Saudi Arabia. A number of design options for repairs for runway pavement were considered and rubblization was chosen as a preferred option for repair. This paper includes the consideration for the assessment and adoption of the concrete rubblized modulus value using the falling weight deflectometer, optimization of the tests for the whole runway using the Heavy Weight Deflectometer HWD testing to replace pits, safely working around the utilities, reasonable assumption of drop height of the pavement and installation of utility conduits in the rubblized layer. Findings of the paper demonstrates resolving technical issues which are not very well covered in the Federal Aviation Authority (FAA) EB-66 such as the additional test strips, minimum areas of rubblization for assessment using test pits, drop in the height of concrete surface and fixing of utilities in rubblized pavement. The case study demonstrates that the rubblization can be successfully carried out in remote locations like empty quarter of Saudi Arabia with carefully carried out detailed site investigations, adopting correct assumed design rubblization modulus, quality control using HWD, protection of utilities while rubblizing and use of polymer modified asphalt for successful project deployment.

基于芯样数据挖掘的沥青路面高温性能发展趋势评价

采用局部多序列动态蠕变试验方法,对高速公路路面连续5 a的现场芯样进行试验,研究其高温性能的发展趋势。结果表明:路面芯样不同层位的高温性能变异系数均超过20%;整体结构和上面层的高温性能均随着服役时间的增长而衰减显著,在设计年限15 a内衰减率低于20%,而超过设计年限后衰减率增至50%以上;不同层位与整体结构的高温性能相比,上面层更弱,中面层最为接近,而下面层更优。

Fatigue Performance of Bridge Deck Pavement Materials

Three beam samples of bridge deck pavement were prepared, with gradation types of AC-13, and AC-16 and combined AC-13＋AC-16. Four-point bending test was adopted to investigate the fatigue performance of these beam samples. The experimental results indicate that the initial bending stiffness is related to the type of beam sample samples decreases as the increase of the controlled strain fatigue resistance and bigger limiting bending strain at pared with single beam sample, the fatigue performance and testing temperature. Fatigue life of these level. The AC-13 beam sample exhibits better the given strain level and temperature. Corn- of combining beam samnle is relatively poor.

NON-DESTRUCTIVE PAVEMENT LAYER THICKNESS MEASUREMENT USING EMPIRICAL MODE DECOMPOSITION WITH GPR

Ground Penetrating Radar(GPR) is an effective Non-Destructive Testing(NDT) technique for highway pavement surveys, which is able to acquire continuous pavement data compared with traditional core drilling method. In this study, we proposed an accurate and efficient method to estimate the thickness of each pavement layer using an air-coupled GPR system. For this work, the main difficulties are estimating each pavement layer's time delay and dielectric constant. We first give the basic signal model for pavement evaluation, and then present an Intrinsic Mode Functions(IMFs) product detector to determine each pavement layer's time delay. This method is based on Empirical Mode Decomposition(EMD), which is an adaptive signal decomposition procedure and proved to be suitable for suppressing noises in GPR signal. The dielectric constant was determined by metal reflection measurement. The laboratory and highway experiments illustrate that the proposed thickness estimation method yields reasonable result, thus meets the requirements of practical highway pavement survey with massive GPR data.

基于“无废城市”理念的高速公路RAP厂拌热再生技术研究

以海南省G98环岛高速改建工程为背景,研究经厂拌热再生技术处理后的沥青路面废弃料(RAP)可回收利用,减少环境污染及经济造价。把RAP掺量分为30%、40%、50%3种进行设计成再生沥青混合料,通过在旧沥青中添加5档不同掺量的再生剂,对比沥青的针入度、软化点、延度3大指标,确定最佳再生剂用量,利用马歇尔试验确定最佳油石比,可制备成级配稳定的AC-20再生沥青混合料,并分别进行高温稳定性研究和水稳定性研究,结果表明:添加不同掺量的RAP均可有效提升高温稳定性,使抗变形能力增强,当RAP掺量为40%时,水稳定性表现为最好,各项路用性能均满足规范所需要求。综上所述,厂拌热再生技术完全可以在海南省进行大规模应用。

玄武岩筋混凝土桥面铺装试验研究

目的研究玄武岩筋替换桥面铺装层中传统钢筋的抗弯性能,为该类加铺玄武岩筋混凝土铺装层提供参考。方法笔者制作了7根玄武岩筋混凝土桥面铺装试验梁和3根普通钢筋混凝土梁对其进行四点加载试验,研究钢筋直径、数量以及铺装层厚度等对试验梁抗弯性能的影响。结果只改变铺装层纵筋类型,铺装层纵筋为玄武岩筋的矩形梁屈服荷载提高了1.23%~8.96%,抗弯承载力提高了0.6%~2.65%;相同筋材类型,随着钢筋直径增大到10 mm,普通钢筋混凝土梁的抗弯承载力提高了13.86%,玄武岩筋混凝土梁的抗弯承载力提高了16.17%;铺装层纵筋数量的改变,对梁的开裂荷载、抗弯承载力的作用较小;只增加铺装层厚度,玄武岩筋混凝土桥面铺装试验梁开裂荷载最大提高了50%,屈服荷载最大提高了14.47%,极限荷载最大提高了11.43%。结论在一定的铺装层厚度和纵筋根数条件下,将铺装层中玄武岩筋代替普通钢筋,不仅可以发挥玄武岩筋抗腐蚀的特点,还能提高抗弯承载力。

Structural Evaluation for Maputo Airport Pavement

Maputo Airport was initially constructed to serve mixed traffic of light and medium aircrafts. With its opening to heavier aircrafts such as B727, DC10, Airbus 340, etc. , structural improvements have become necessary. For this purpose, structural evaluation were described and performed using falling weight deflectometer. Results show that while subgrade response to loads appears more consistent with depth, surface layer of the pavement is significantly influenced by the layer thickness as well as mechanical properties of pavement materials. Load magnitude also affects pavement performance. But loading conditions show an equivalent or even greater influence on pavement performance.

基于多尺度加载试验的沥青路面结构参数设计方法

基于江苏省典型路面结构,通过改变试件尺寸、温度和荷载作用次数对SMA-13、SUP-20和SUP-253种材料开展动态模量和蠕变试验。将结果耦合到修正的Burgers模型并在ABAQUS中开发用户材料子程序模型。对室内单轴试验分别采用应变硬化和子程序模型进行模拟、对小型和大型路面加载试验分别进行车辙模拟。结果表明3种材料的动态模量随试件尺寸增加而增大、温度升高而减小;SUP-25的疲劳损伤效应最为明显,在重复加载5400次后损伤值达到了0.419。子程序模拟单轴试验的误差小于应变硬化模型、车辙模拟与小型和大型加载测试结果的误差分别为3.08%和2.83%,说明模型在单层及多层复合材料的应用中都是有效的。模拟表明夏季高温100万次加载的变形量为春季常温的1.8倍;行车速度由22 km/h增加至120 km/h时,变形量减少72.6%;轴载增加100%,车辙深度增加48.52%,表明在高温地区低速路段要尤其限制车辆超载。累计标准轴载作用次数超过2500万次,车辙变形进入加速累积阶段,须及时对该路面结构进行养护维修。

基于足尺加速加载试验的高速公路沥青面层力学性能与高温性能研究

针对高速公路改扩建工程老路沥青面层,在120万次足尺加速加载试验条件下,采用动态模量试验评价其力学性能,采用贯入强度试验与汉堡车辙试验评价其高温性能。动态模量试验结果表明,20℃、10 Hz条件下沥青面层芯样0~120万次的动态模量维持在相对稳定的状态,最大值与最小值偏差约为6.9%。贯入强度试验结果表明,0~120万次的沥青面层芯样的单轴贯入强度相对稳定,老路的加铺层、上面层、中面层、下面层的贯入强度变化量分别为-0.04 MPa、0.11 MPa、-0.03 MPa、0.18 MPa。汉堡车辙试验结果表明,加铺层和上面层的芯样总体维持在稳定的状态,中面层和下面层芯样试验结果有一定程度的波动,下面层变化相对明显:汉堡车辙深度的变化率为114.56%,蠕变斜率的变化率为150%。根据120万次足尺加速加载试验结果,该高速公路改扩建工程老路沥青面层在力学性能和高温性能方面表现稳定,扩建后的路面能够满足交通荷载的使用要求。

沥青路面内部缺陷无损检测技术研究综述

为了快速、准确地检测出沥青路面内部缺陷和病害,以便及时采取养护或其他处理措施,保障道路行车安全。同时,为促进沥青路面内部隐性病害和缺陷无损检测技术的发展,对现有沥青路面内部缺陷的无损检测技术进行了综述。分别综述了探地雷达的基本原理、在沥青路面检测中的应用以及探地雷达图谱的智能识别,超声波检测技术的检测原理、超声波的衰减规律研究和其在路面内部缺陷检测中的应用与研究,红外热成像技术、核子密度仪、无核密度仪和瑞利波法的检测原理和在沥青路面内部缺陷检测中的应用与研究,最后汇总了各检测技术的检测原理、检测缺陷类型和优缺点等,并探讨了各检测技术存在的问题和未来的发展方向,为沥青路面内部缺陷无损检测技术的进一步应用与研究提供了参考和依据。

钢桥面沥青铺装磨耗层抗滑及耐磨耗性能分析

针对钢桥面铺装的厚度限制及密水性的要求,采用沥青混合料摩擦特性测试仪、激光扫描仪等设备对四种常用于钢桥面磨耗层的混合料进行了加速加载磨耗试验,并采用Asymptotic模型对数据进行拟合分析,从而确定了沥青混合料抗滑性能参数与磨耗次数之间的相关性。结果表明:随着磨耗次数的增加,沥青混合料的动态摩擦系数、摆值(BPN)、构造深度(MTD)及断面平均构造深度(MPD)均呈现出初期快速下降,后期逐渐减缓的趋势;Asymptotic模型可对四种混合料抗滑性能与磨耗次数之间的关系进行准确表征,相关性系数达到0.95以上;从抗滑性能来看,改性沥青SMA13与EA10表现出了明显优势,特别是EA10的动态摩擦系数及摆值(BPN)两个指标均比其他三种混合料的高。然而,EA10的构造深度(MTD)通常难以达到0.8的标准。结合工程实践经验,建议在磨耗层性能满足要求且其厚度允许的前提下,优先考虑采用改性沥青SMA13。同时,由于现行规范要求的抗滑性能检测方法之间存在一定差异,宜扩大样本来源,以更全面地阐明这些方法与路面抗滑性能之间的相关性。

土工格室加固砂基未铺路面APT试验研究

加速路面试验是在相关环境条件下通过施加受控车轮载荷来评价路面性能的一种有效方法。将四个未铺路面路段分为加固和未加固两部分进行加速路面试验。第1和第4部分是砂基,是在破坏后用骨料基替换的未加固部分。第2和第3部分是在骨料覆盖层下用新型聚合物合金(NPA)土工格室加固的砂层。在经过一定次数车轮碾压后,测量每个路段的车辙深度。用应变片监测NPA土工格室不同位置的水平应变。试验结果表明,NPA土工格室在改善未铺路面的稳定性和减少永久变形方面具有显著效果。在特定的试验条件下,土工格室加筋砂层的性能相当于相同厚度的A-1-a骨料,显示出保持土工格室结构完好无损对确保NPA土工格室加固基底的足够性能具有重要意义。最后的试验应变片测量显示,车轮路径下的NPA土工格室承受拉伸应力,而车轮路径外的土工格室承受压缩应力。