摘要 车辙是沥青路面特有的一种损坏现象，据统计，30％以上路面损坏与车辙有关，且近年来有增加的趋势，而且对沥青路面的使用性能影响极大，多少年来一直困扰着中外道路工作者。沥青路面的车辙是由于重复荷载诱发的永久变形的累积，它主要是由各结构层内的应力状况和材料的相对强度决定的。沥青路面的永久变形是由上面的沥青面层，粒料基层和土基三部分共同组成的。 由于当前半刚性基层作为我国主要的沥青路面基层形式，车辙研究主要集中在沥青面层而对粒料层的变形特性研究很少。随着松散粒料具有良好的排水及消除反射裂缝功能和优良的经济性被人们再认识后，含粒料基层的柔性路面结构也必将成为我国未来高等级公路路面结构多样化发展的重要结构之一。基于上述背景，论文就松散粒料在重复荷载下的变形特性和控制其永久变形的路面设计方法和指标进行了研究，为粒料基层沥青路面的推广提供技术支持。 论文首先选取松散粒料作为路面基层的传统柔性路面结构、松散粒料作为应力吸收层的倒装结构和松散粒料作为半刚性基层底基层的半刚性路面结构三种典型结构，采用弹性层状理论分析了粒料层的应力分布状况。其中重点考虑了粒料层作为柔性路面结构基层时荷载大小、土基强度、粒料层非线性应力依赖特性、砸层厚度及模量和粒料层厚度及模量等因素对其三向受力的影响。综合力学分析结果总结了粒料层的三向应力范围，为室内动三轴试验制定加载标准提供依据。 其次，论文分析了影响粒料永久变形的主要影响因素，并结合力学分析得到的粒料层应力分布状况，采用四种级配碎石混合料进行了不同偏应力、围压和含水量等试验工况下的重复荷载动三轴试验，分析了各因素对级配碎石永久变形特性的影响，并根据室内实验得到的永久变形曲线通过非线性最小二乘法拟合出了粒料材料弹塑性应变比与荷载作用次数、回弹模量和含水量间的永久变形预估模型，相关性检验分析表明本次研究建立的预估模型合理且具有一定的精确度。同时根据得到的永久变形预估模型提出了分层应变总和法计算沥青路面粒料层车辙变形量的方法。 在以上工作的基础上，论文以现行规范为基础，结合目前国内外沥青路面设摘要计方法和设计指标，从沥青路面粒料层发生永久变形破坏角度出发，提出了控制沥青路面粒料层不发永久变形破坏的设计指标和设计方法。并提出了设计流程图，给出了典型算例。 最后，关于进一步工作的方向进行了简要的说明。 关键词：：沥青路面，粒料基层，永久变形，动三轴试验，非线性最小二乘法，永久变形预估模型，设计指标，设计方法。 ABSTRACT Rut is a unique damage phenomenon of asphalt pavement. According to statistics，more than 30％ofthe asphalt pavement damages is related to rut,and in recent years，it is an increasing trend，more than，rut has great impact on the performance of asphalt paVement．DomeStic and foreign road workers have been puzzled by the rut for so many years．Rutting is the load．induced permanent deformation of a flexible pavement. Depending on the magnitude of the load and the relative strength of the paVement layers，permanent deformation Can occur in the subgrade，the base，or theupper hot mix asphalt(HMA)layers． Because nowadays asphalt pavement with semi-rigid base course is the primary Stnlcnlre type in 0111"country,a great deal of rutting research is focused on asphalt layer but seldom on unbound granular layer．As granular bade draws much attention for its good drainage，eliminating reflect crack and economical property,granularbase asphalt pavement will be one of the important structures of the development of pavement Structure diversification in the future．This paper mainly studies the pennaIlent deformation performance of unbound granular materials and asphalt pavement structure design method and indexes．It will provide technique for extension ofgranular base asphalt pavement． Firstly，Through choosing granular base as three type pavement structure(base layer of flexible pavement、stress dissipation layer of invert pavement structure-base layer of semi．rigid pavement)mechanics response is carried using elastic layer theory．as granular base is the base layer of flexible pavement,some main faCtorswhich influence the stress fieldof granular base such as load、the strength of subgrade．soil、the nonlinear stress dissipation performance of granular layer、the thickness and modulus of asphalt surface、the thickness and modulus of granular base ale analyzed especially．The paper summarizes the three-dimensional stress ranges from the pavement mechanics analysis results and it provides bases for tlle loading criterions of repeated load triaxial test in laboratory． Secondly,the main factors influencing granular permanent deformation performance ale analyzed．Considering granular layer stress mechanics analysis result, repeated load tests ale carried under different deviator stress，confining pressure and moisture contents，including four granular mixes．Base on the nonlinear least squares111method．the granular permanent deformation prediction model including times of repeated load，modulus and moisture content is brought forward from permanent defonnation curveS．The result of the correlative analysis shows that the model is I℃ason2lble and also has the credible precision．And a layered summation method which predicts permanent deformation of granular layer in flexible pavement is given． Thirdly, based on all of upon working,the dissertation set up an asphalt pavement design method and design index which control the permanent deformation of granular layer through studying different design methods and index in country and overseas．In the same time，the design flow chart and design example also ale bringforwarded． Finally，the further research direction iS briefly accounted for. Key Words: asphalt pavement，granular base，permanent deformation，repeated load triaxial test，nonlinear least squares method，permanent deformation prediction model，design method，design index. |
博士论文