沥青稳定碎石基层高温性能试验研究

文中结合河南禹登（禹州-登封）高速公路工程,采用大粒径ATB-30和ATB-40两种沥青稳定碎石混合料级配,通过车辙试验和单轴蠕变试验比较不同沥青标号和级配类型混合料的高温性能,并分析沥青混合料高温稳定性的影响因素和原因。     

大粒径碎石沥青稳定排水基层混合料设计方法的研究

对大粒径碎石沥青稳定排水基层混合料设计方法进行系统研究,提出排水性大粒径碎石沥青稳定基层级配,通过析漏试验、飞散试验和马歇尔试验确定最初沥青用量,并通过水稳定性试验、高温性能试验和疲劳性能试验,确定最佳沥青用量。     

几种不同级配大粒径沥青混合料大马歇尔试件研究

采用析漏试验和大马歇尔试验方法确定开级配大粒径沥青混合料最佳沥青用量。通过实验研究几种不同级配大粒径沥青混合料的抗车辙能力、水稳定性和力学性能。研究表明,大粒径沥青混合料均具有良好的高温稳定性,水稳性能随着空隙率的增大呈减小趋势,LSM力学性能优于OLSM。     

排水性沥青稳定碎石混合料设计

结合某高速公路排水基层试验路,对沥青稳定碎石排水基层混合料设计进行了试验研究.采用谢伦堡沥青析漏试验、肯塔堡飞散试验确定沥青碎石最初沥青用量范围,并进行水稳定性、APA车辙和高温性能试验检验,最终确定沥青稳定碎石排水基层的最佳沥青用量.     

大粒径沥青混合料高温性能对比分析

为了评价大粒径透水性沥青混合料的高温性能,采用车辙试验测试了不同厚度的LSPM-30车辙试件的动稳定度,推荐了适宜的车辙试件厚度。然后采用该厚度推荐值,测试了不同结构类型的大粒径沥青混合料的动稳定度和总变形量,同时分析了其车辙发展规律。试验结果表明:推荐8cm厚度作为LSPM-30车辙试件的标准厚度;骨架型的大粒径沥青混合料高温性能优于悬浮密实型的大粒径沥青混合料;车辙试验变形曲线初始变形阶段和线性发展阶段的割线斜率可以分别用于评价大粒径沥青混合料早期车辙深度和长期高温稳定性。     

小粒径大空隙排水沥青混合料性能试验

为实现超薄排水沥青路面的设计与应用,采用渗透性试验、摆式摩擦系数试验、动态摩擦系数试验、声波吸收系数试验、肯塔堡飞散试验、车辙试验、低温弯曲试验和冻融劈裂试验,对最大公称粒径4.75 mm和13.2 mm的2种开级配型式与2种不同沥青混合料类型组合而成的4种大空隙排水沥青混合料的综合性能进行试验评价。试验结果显示,最大公称粒径4.75 mm级配形式的开级配沥青混合料的透水性能、摩擦性能及抗松散能力比最大公称粒径13 mm级配的沥青混合料略优,具有很好的排水降噪功能。环氧沥青混合料的使用,有利于提高小粒径大空隙排水沥青混合料的整体路用性能。     

预拌碎石对GMA浇注式沥青混凝土高温性能的影响

为研究预拌沥青碎石对钢桥面铺装结构高温抗车辙性能的影响,依据港珠澳大桥钢桥面铺装实体工程,开展GMA浇注式沥青混凝土的高温性能室内试验研究。首先设计GMA10和SMA13级配沥青混合料,然后制备不同预拌沥青种类(AH70#,SBS)、不同预拌沥青掺量(0.2%,0.4%,0.6%,0.8%)、不同粒径(5~10 mm,10~15 mm,15~20 mm)的单级配碎石,分析不同粒径、撒布量、撒布方式、预拌沥青种类与掺量对单层GMA浇注式沥青混凝土和组合结构(SMA+GMA)高温性能的影响。结果表明:预拌碎石撒布可显著提高GMA浇注式沥青混合料的高温性能;在其他相同条件下,撒布粒径10~15 mm的预拌碎石对提高GMA浇注式沥青混合料的高温性能最为明显,高达30%左右;随着预拌碎石撒布量的增加,GMA浇注式沥青混合料的高温改善作用逐渐增强,撒布量在10~12 kg/m2改善效果最佳;碎石撒布方式和预拌沥青的类型对提高浇注式沥青混合料的车辙动稳定度影响较小;随着预拌沥青掺量的增加,GMA浇注式沥青混合料高温性能改善作用先增强后减弱,预拌沥青掺量0.2%~0.6%较为合理;干拌碎石在浇注式沥青混合料中的的隔热效果优于预拌沥青碎石的;预拌沥青碎石的撒布改善了组合结构的高温抗车辙性能,车辙深度降低10%左右,车辙动稳定提高25%左右;组合结构70℃车辙动稳定度指标更能真实反映南方湿热高温环境下钢桥面铺装结构的高温抗车辙性能。     

大粒径沥青混合料基层施工技术

大粒径沥青混合料(LSAM)基层由于其良好的路用性能而备受关注,但粒径大、容易产生离析、难以压实。该文通过大粒径沥青碎石试验路的施工实践,选定最优级配作为试验路的设计级配;介绍了防止LSAM离析和保证压实的有效措施;并通过对弯沉、回弹模量和钻芯试验的检测,评价了大粒径沥青碎石基层的路用性能,为LSAM的设计和施工提供了依据。     

沥青稳定碎石基层混合料设计方法的研究

对沥青稳定碎石基层混合料设计方法进行了系统研究,通过室内试验,提出了沥青稳定碎石基层混合料的级配,评价了沥青稳定碎石基层混合料的路用性能,并且,采用了大马歇尔法、旋转压实体积法、GTM法3种方法研究了沥青稳定碎石基层混合料最佳沥青用量的确定方法.     

大粒径沥青混合料路用性能研究

为研究大粒径沥青混合料路用性能,通过车辙试验、浸水马歇尔试验、小梁弯曲试验分析3种级配大粒径沥青混合料的水稳定性、高温稳定性及低温抗裂性能,并对试验路段进行车辙深度与弯沉检测。结果表明:3种级配的残留稳定稳定度均大于80%,动稳定度均大于800次/mm,且随着粗集料的增多混合料的低温变形能力得到加强,但随着温度的降低,其低温抗裂性能有所下降,大粒径混合料的实际路用性能也较好。     

掺加改性剂沥青混合料抗车辙性能研究

对PR和RA不同掺量的AC-20C和Sup-20两种级配的沥青混合料进行车辙试验,且应用灰色关联分析及统计学检验方法对车辙试验结果分析。结果表明马歇尔稳定度和马歇尔模数是影响车辙试验结果的主要因素;在PR或RA相同的条件下,级配由AC-20C转变为Sup-20时,对车辙试验结果影响较小。PR对混合料的改性性能优于RA。     

RLWT车辙仪车辙评价及应用研究

介绍使用一种较新的RLWT车辙仪,对分别使用不同沥青类型的混合料进行抗车辙能力评价,并与国标车辙仪的试验结果作对比,得出RLWT车辙仪和国标车辙仪的单位变形荷载作用次数具有很好的相关性,能有效地评价沥青路面的抗车辙能力。实际工程检测结果表明:RLWT车辙仪具有较高的推广应用价值。     

Indirect method for wheel–rail force measurement and derailment evaluation

Wheel set flange derailment criteria for railway vehicles are derived and the influence of wheel–rail contact parameters is studied. An indirect method for wheel–rail force measurement based on these derailment evaluation criteria is proposed. Laboratory tests for the calibration of strain–force devices on the bearing box are carried out to determine the relationship between the applied force and the measured strain. The simulation package, SIMPACK, is used to develop a passenger car model to generate wheel–rail forces and vibration signals. Different cases are considered in this model to provide an accurate validation of the identified wheel–rail forces. A feasibility test is conducted in the Beijing Loop test line using a passenger car equipped with a set of strain gauges on the wheel set. The comparison of the force time history applied to the instrumented wheel set and that obtained using the indirect method is presented.     

RLWT与APA车辙试验加载模式比较分析

旋转车辙仪(RLW T-R otary Loaded W hee l T ester or R u tm eter)于20世纪90年代末开始在美国出现,因其轻便、易用,迅速受到关注。研究表明,RLW T与沥青路面分析仪(APA)、国际车辙仪的相关性都不理想。本文利用数字图像处理技术对RLW T与APA车辙试验的加载模式进行了分析,通过量测RLW T试件、APA试件与原样试件中粗集料颗粒长轴与X轴夹角的差异,得出结论:RLW T与APA车辙试验的加载模式存在较大差异。     

基于车辙试验的空隙率效应模型的建立

采用常见的3种沥青混合料，旨在通过室内车辙试验，分析不同试件空隙率对车辙试验结果的影响程度，探讨了不同空隙率试件试验结果之间的内在联系。通过大量车辙试验，对比不同孔隙率试件车辙试验结果，发现孔隙率变化会对试验结果产生重大影响。同时，在室内车辙试验的基础上，对不同空隙率、不同轮载作用次数下车辙深度进行回归分析，建立了标准试验条件下，混合料车辙深度的空隙率效应模型（VEM）。分析表明，以7％作为基准空隙率可以得到与实际更为接近的预估车辙深度。该模型可预估不同空隙率混合料在不同轮载作用次数下的车辙深度，也可对不同空隙率试件在不同轮载作用次数下的车辙深度进行转化。     

汽车轮速传感器仿真方法

轮速传感器测量汽车轮速信号,用于制动、发动机及变速箱等众多系统控制,是汽车最关键的部件之一。新车型开发阶段,为了对汽车制动防抱死系统(ABS)及早有效的开发验证,需要对轮速传感器进行仿真模拟。文章针对最常用的主动式轮速传感器进行测试与分析,通过设计信号调理电路,成功搭建了ABS硬件在环仿真平台,既简化了汽车开发阶段的验证与测试,又节省了开发成本。     

A Comparison of Alternative Intervention Strategies for Unintended Roadway Departure (URD) Control

This paper investigates the use of several different inputs for the control of a vehicle, in the context of URD. In this investigation, the goal of the URD controller is to provide an intervention in the event of the vehicle leaving the road. The types of inputs that will be considered are (i) Four Wheel Steering, (ii) Front Wheel Steering, (iii) Four Wheel Brake Steering, (iv) Front Wheel Brake Steering, and (v) Rear Wheel Brake Steering. The controller design is an LQ controller based on the simplified dynamics of a 2 degree of freedom bicycle model. However, the analysis of the different strategies are performed on a 7 degree-of-freedom nonlinear vehicle model. The key contribution of this paper is the quantitative evaluation of the relative efficiencies of each of these input strategies being examined. Unlike most control schemes, the performance measure to be used will not be the output tracking error of the system. Instead, the metric of performance is the ratio of peak tire force used versus available tire force or, in other words, the actuator response relative to the maximum available actuator capability.     

A Comparison of Alternative Obstacle Avoidance Strategies for Vehicle Control

In Alleyne (1996) several vehicle control options were considered for Unintended Roadway Departure (URD) prevention and conclusions were drawn as to the efficacy of each method. This companion paper investigates the use of several different inputs for the control of a vehicle, in the context of Obstacle Avoidance for autonomous vehicles. In this investigation, the goal of the controller is to provide an intervention in the event of the vehicle detecting an obstacle in its path. The five types of inputs that will be considered are (i) Four Wheel Steering; (ii) Front Wheel Steering; (iii) Four Wheel Brake Steering; (iv) Front Wheel Brake Steering; and (v) Rear Wheel Brake Steering. The controller design is an LQ controller based on the simplified dynamics of a 2 degree of freedom bicycle model. However, the analysis of the different strategies are performed on a more complete, nonlinear vehicle model. A key contribution of this paper is the quantitative evaluation of the relative efficiencies of each of these input strategies being examined. Unlike most control schemes, an important metric of performance is the ratio of peak tire force used versus available tire force. The conclusions reached in this paper shed additional light on appropriate input actuator methods for vehicle guidance and control.     

A Comparison of Alternative Obstacle Avoidance Strategies for Vehicle Control

SUMMARY

In Alleyne (1996) several vehicle control options were considered for Unintended Roadway Departure (URD) prevention and conclusions were drawn as to the efficacy of each method. This companion paper investigates the use of several different inputs for the control of a vehicle, in the context of Obstacle Avoidance for autonomous vehicles. In this investigation, the goal of the controller is to provide an intervention in the event of the vehicle detecting an obstacle in its path. The five types of inputs that will be considered are (i) Four Wheel Steering; (ii) Front Wheel Steering; (iii) Four Wheel Brake Steering; (iv) Front Wheel Brake Steering; and (v) Rear Wheel Brake Steering. The controller design is an LQ controller based on the simplified dynamics of a 2 degree of freedom bicycle model. However, the analysis of the different strategies are performed on a more complete, nonlinear vehicle model. A key contribution of this paper is the quantitative evaluation of the relative efficiencies of each of these input strategies being examined. Unlike most control schemes, an important metric of performance is the ratio of peak tire force used versus available tire force. The conclusions reached in this paper shed additional light on appropriate input actuator methods for vehicle guidance and control.     

新型轮挡研究

安全是一个永恒的主题,它是赖以生存和发展的基础。地面安全是行业监管的工作重点。在地面停放过程中,由于天气、环境、突发意外事件、人为失误等因素可能会造成的地面事故。轮挡指在存放库或其他临时场地时用于限制轮胎位置的装置,轮挡是常用的地面安全设备。