行车荷载作用下沥青路面的动粘弹性分析

行车荷载作用下的沥青路面响应对沥青路面的设计和维护具有重要的参考意义。本文利用有限元方法,基于粘弹性理论和结构动力学理论,考虑了路面层间接触状态,分析了行车荷载作用下沥青路面的结构响应。结果显示,层间接触状态越好,路面的弯沉响应和应力响应越小;由于沥青材料的"剪切变稀"特性,结合行车荷载下路面的剪切应力分布特征,在轮迹两侧会形成拥包;路面的自振会对同振型方向的结构响应存在较大影响。     

基于层间接触状态的沥青结构层受力分析及数值计算研究

通过建立有限元模型的方法,用摩擦系数表征路面各结构层之间的黏结状态,建立符合层状弹性体系理论的连续绑定模型以及层间非连续的接触模型,并对2种模型在相同荷载作用下的最大剪应力大小及特征进行了数值模拟。深入研究了接触模型中变化层间摩擦系数时路面、基层以及底基层的弯沉大小和分布规律,并分析了半刚性基层沥青路面的结构特点和保障层间连续的工程措施。     

大孔隙聚合物改性水泥混凝土路面基层结构受力分析

作为一种新型路面基层,大孔隙聚合物改性水泥混凝土基层能够降低沥青路面厚度,延长路面使用寿命,降低公路建设和养护成本,提高路面的使用质量,但其力学作用机理尚不明确。文章基于弹性层状体系理论的BISAR程序对以该结构为基层的沥青路面基面层进行力学分析,研究在不同车辆荷载、不同的PCPB厚度、不同荷载作用位置等因素下,路面各结构层的应力应变情况并与以往半刚性基层做出比较,从而得出该结构在减少裂缝、延长路面使用寿命和质量方面的作用机理;应用ANSYS有限元分析方法,验证车辆荷载作用下PCPB作为路面基层对沥青面层的力学响应;最后通过正交试验,确定PCPB的最佳结构组合形式。     

不同层间状态对沥青路面U形破坏的影响

为了分析不同层间接触状态对沥青路面"U形"破坏的影响,以典型半刚性基层沥青路面为研究对象,选择纵向水平拉应力σ3和竖向剪应力τ13作为表征U型开裂的力学指标,利用ABAQUS有限元软件,分析了层间接触条件对沥青路面力学的影响。计算结果表明:层间接触状态对沥青路面"U形"破坏的产生有显著的影响,且面层接触状态对路面"U形"破坏的产生的影响程度要比基面层间接触状态对其的影响程度大得多。因此,若想有效地控制"U形"破坏的产生,需加强沥青面层之间的粘结。     

基于BISAR软件的路面结构受力分析

运用BISAR3.0计算程序对半刚性基层沥青路面结构进行分析,在不同的半刚性材料模量,不同层间接触以及不同荷载作用下,分析路表弯沉、半刚性基层层底拉应力和沥青面层层底拉应力三个指标的变化。由此得出不同情况下路面结构的受力规律,为路面结构设计提供参考。     

层间接触状态对沥青路面结构的力学响应分析

沥青路面结构的设计应保证路面在长期使用过程中尽量少的发生结构性损坏,允许由于材料的老化和疲劳发生一些路表功能性的损坏。保证路面结构的结构性不损坏,可以提高路面的路用性能,增加路面使用年限。在设计的使用年限内养护部门仅需对路表做相应处理即可快速恢复表面功能,避免对路面结构进行大型翻修改建,故要求路面结构内部在车辆荷载作用下产生的力学响应分布合理。基于此,对不同层间接触状态对于沥青路面结构的力学响应进行深入分析。     

橡胶应力吸收层对半刚性基层沥青路面力学特性的影响分析

运用有限元分析软件ANSYS(V12.1)建立半刚性基层沥青路面结构模型,对比了半刚性基层沥青路面在静荷载以及静荷载和水平荷载耦合作用下,设置高弹性橡胶沥青应力吸收层前后的路面结构力学响应,通过分析发现:路表竖向位移对水平荷载不敏感,高弹性橡胶沥青应力吸收层对路面整体刚度的影响随着水平荷载系数的提高而有所提高;沥青层底弯拉应力对水平荷载不敏感,高弹性橡胶沥青应力吸收层对路面整体强度的影响维持在23%的水平;沥青层最大剪应力随着水平荷载提高而显著增大,高弹性橡胶应力吸收层对路面整体抗剪强度的影响同样随水平荷载提高而提高,当水平荷载系数为0.5时,整体抗剪强度提高率为32%。     

沥青路面在不同层间接触条件下的力学性能研究

为了应对沥青路面常见病害的发生，本文用BISAR3．0软件计算了三种典型路面结构在不同层间接触条件下的力学特征。通过研究沥青路面在不同层间接触条件时于深度方向和横向的力学响应，为沥青路面的施工和路面结构设计提供理论参考。     

北京地区沥青铺面防水黏结层的选择

为满足北京地区道路沥青路面层间黏结防水的要求,对防水黏结层的类型、作用进行了区分,对防水黏结性能的试验检测方法进行了总结,根据北京市道路交通荷载状况下的路面结构需求,对适用的防水黏结层进行了性能分析和推荐。     

固化剂水泥稳定土基层沥青路面结构数值分析

采用路邦固化剂水泥稳定土作为某高速公路路面结构的基层材料,应用三维有限元软件计算了该路面结构在四种典型车型额定荷载、欠载、超载等荷载工况作用下的力学响应,重点分析了路面弯沉和水平、竖向应力等数据。结果表明:采用路邦固化剂水泥稳定土作为基层材料的沥青路面结构具有较强的路面承受能力,采用固化剂作基层稳定材料是可行的。     

Effects of overlay designs on reliability of flexible pavements

Management of flexible pavements requires timely application of preventive maintenance and rehabilitation actions such as overlays. These actions are an integral part of a design strategy that minimises the use of recourses over the pavement's life-cycle. The objective of this paper is to develop a reliability model for flexible pavements that accounts for the effects of overlay designs. In this paper, the pavement responses are determined by the linear theory of elasticity for the system of pavement layers, while the pavement reliability is represented as a series system of two failure criteria: fatigue cracking and rutting. To illustrate the developed model, a numerical study is presented. Sensitivity and importance measures are computed for the parameters and the random variables included in the limit state functions. The sensitivity measures suggest that the initial asphalt layer thickness and the sub-grade stiffness are the critical predictors of the pavement performance after application of a structural overlay.     

Thiopave改性沥青路面力学响应研究

基于Thiopave改性沥青路面良好的高低温稳定性,采用有限元软件对典型半刚性基层沥青面层进行计算,得到不同沥青面层层底力学响应,并对计算结果进行对比研究,得到的主要结论如下：Thiopave沥青路面层底弯拉应力显著大于SBS沥青及基质沥青路面,路表轮隙中心处弯沉值小于SBS沥青及基质沥青路面;随着SEAM掺量的增加,...     

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Asphalt concrete (AC) overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing pavements. The strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement material. This study was conducted to analyze the influence of anisotropy, modulus gradient properties, and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays, as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA). The mechanical behaviors of the AC overlay were numerically obtained using the three-dimensional finite element method with the aid of ABAQUS, a commercial program. Variations in the AC overlay’s modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients method. Comparing the mechanical behavior in terms of surface deflection, stress, and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC overlay. In addition, the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore, future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.     

胶粉负载型路面尾气降解复合材料的路用性能

针对TiO2光催化降解尾气技术难应用于沥青路面的弊端,试验研究了可用于各类路面的尾气降解材料的路用性能和尾气降解效果.结果表明:胶粉负载光催化剂型路面尾气降解复合材料的力学性能和耐久性均满足相关标准要求,用沥青黏结层者抗冲击性、拉伸黏结强度和低温抗裂性较好,用环氧树脂黏结层者高温稳定性和水稳定性较好;该降解复合材料会降低路表宏观构造深度,但胶粉摩阻作用能提高路面综合抗滑性,对水泥混凝土路面板抗滑性的改善效果优于沥青路面板,可使前者摩擦摆值提高11.5％;该降解复合材料1h可降解95％(质量分数)初始质量浓度0.002％的NO2气体,且水稳定性较好,浸水7d仍具有1h降解35 ％NO2气体的降解效果.     

Geosynthetic-stabilized flexible pavements: Solution derivation and mechanistic-empirical analysis

Geosynthetics have been widely applied in flexible pavements for decades. However, the mechanistic-empirical analytical approach for geosynthetic-stabilized flexible pavements based on the elastic solution derived from the layered elastic theory has not been established. In this study, the solution for a typical three-layer geosynthetic-stabilized flexible pavement was derived according to the layered elastic theory. In the derivation, lateral restraint and tensioned membrane effect of geosynthetics quantified in terms of layer permanent deformations were considered at the interface as a continuity condition. The derived solution was then incorporated into the mechanistic-empirical approach for the calculation of pavement rutting and fatigue cracking. The result indicates that the solution derived in this study is capable of analyzing the geosynthetic-stabilized three-layer flexible pavement. The pavement elastic responses calculated using the solution obtained in this study are in line with those by the previously established solutions in the literature. The rut depths estimated using the proposed solution reasonably match those measured in the previous study. For rut reduction, the geosynthetic placed underneath the base layer is more effective. For the tensile strain relief at the bottom of the asphalt layer, the geosynthetic placed at the bottom of the asphalt shows more benefit.     

某城市道路刚性组合式路面水损害分析及防水技术

某城市道路刚性组合式路面出现了龟裂、沉陷、松散、坑洞、补块损坏等水损害现象,主要与路面结构不合理、施工质量不佳、养护不当等因素有关。介绍了该城市道路改造工程中采用的小空隙率沥青混合料面层、铺设SBR改性乳化沥青稀浆封层、设置胶粉改性沥青防水防裂层、级配碎石排水层等综合防水技术。     

动荷载下饱水沥青路面黏弹性分析

为深入剖析沥青路面动水损坏机理,基于多孔介质理论,建立饱水沥青路面有限元模型,比较分析面层为弹性和黏弹性,以及面层饱水和表面层饱水的动力响应,并分析孔隙水压力峰值的发展规律和周期荷载对孔隙水压力的影响。结果表明,黏弹性面层的竖向变形和负孔隙水压力较大,正孔隙水压力较小,面层底部未出现水平拉应力;孔隙水压力峰值的大小及出现的位置发生改变,正、负孔隙水压力峰值出现的最终位置分别在底基层内和下面层内;与路面完全饱水相比,面层饱水和表面层饱水的竖向变形较大,面层饱水的面层层底的负孔隙水压力较大,而表面层饱水的表面层底负孔隙水压力较小;周期荷载的作用使孔隙水压力出现明显的周期性正、负交替,面层间的负孔隙水压力峰值变化率较基面层间的大。据此分析得出,面层特性对饱水沥青路面的动力响应有较大影响,面层饱水对基面层的损害严重,沥青路面的水损坏主要发生在面层的中下部。     

UNCERTAINTIES OF ASPHALT LAYER THICKNESS DETERMINATION IN FLEXIBLE PAVEMENTS-INFLUENCE DIAGRAM APPROACH

The thickness of pavement layers is an important parameter used in Pavement Management Systems (PMS). Thickness data are used for pavement condition assessment, performance predictions, selection of maintenance strategies and rehabilitation treatments, basic quality assessment, and as input to overlay thickness design. Pavement thickness is usually determined from direct testing such core samples, nondestructive testing such as radar, or historical records such as pavements network database. This paper proposes the use of Bayesian Influence Diagrams as a tool in providing a probabilistic model for thickness determination procedure in flexible pavements. The Bayesian Influence Diagram Model is presented as a framework for addressing uncertainties involved in capturing quantitative and qualitative information in the asphalt layer thickness determination procedures. The model is also used to perform value of information analysis in the determination of pavement layer thickness. The Influence Diagram representation facilitates the assessment of coherent prior distributions and makes it easier for knowledge engineers and other decision makers to express and understand more general kinds of dependency and independency assumptions.     

废机油残留物再生沥青的抗老化性能

以废机油残留物(REOB)作为沥青再生剂,从REOB自身、REOB再生沥青及REOB再生沥青混合料3个层次进行老化性能研究.通过延时薄膜烘箱老化试验(TFOT)(老化时间分别为5、10、15、20、25h),测定了REOB再生沥青、RA5再生沥青和基质沥青的质量及黏度变化,并采用弯曲梁流变试验评定3种沥青老化后的低温性能;利用对应的3种沥青混合料设计铺筑了室内足尺试验路面层,并采用自主研发的回转式加速加载试验系统(RALT)在常温及高温下开展了路面加速加载试验来评估其长期抗疲劳性能.结果表明:REOB再生沥青的抗短期老化性能(TFOT老化时间不超过10h)比RA5再生沥青好,但不如基质沥青,而其抗长期老化性能(TFOT老化时间不少于15h)最差;在长期老化后,REOB再生沥青因劲度急增且应力松弛性能骤降从而极易导致低温开裂;高温老化明显加剧了REOB再生沥青混合料路面在RALT加速加载条件下弯沉值的增长,使其在3种路面中最易发生疲劳破坏,说明将REOB用于再生沥青路面时,易使路面出现过早过度破坏.     

沥青路面多尺度结构的荷载响应分析

为了从材料细观结构角度研究沥青路面结构的荷载响应,采用离散元方法,建立了柔性基层沥青路面典型结构模型,并进行了竖向荷载作用下沥青混凝土层应力和应变的计算,通过与经典路面响应程序计算结果的比较,验证了路面结构离散元模型和离散元计算方法的正确性.以验证过的路面结构模型为基础,采用较小的细观尺度描述了沥青混凝土结构层底部位置处粗集料、沥青砂浆和空隙的分布和体积大小,从而建立了路面结构的多尺度模型,并计算了荷载作用下多尺度模型的响应.结果表明,荷载引起的路面结构应力和应变在沥青混凝土内呈现显著的不均匀分布特征;粗集料与砂浆接触处的应力明显高于沥青砂浆内部的应力,两者的比值随着沥青砂浆模量的降低而增大;考虑材料细观结构后,粗集料与砂浆接触处的荷载响应明显高于宏观路面结构响应,而沥青砂浆内部的荷载应力小于不考虑细观结构时的宏观路面结构应力.