【作者】 郭红兵；

【导师】 陈拴发；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2013， 博士

【摘要】 为了解决半刚性基层沥青路面、旧水泥混凝土路面沥青加铺层结构以及刚性基层沥青路面共同存在的沥青面层反射裂缝问题，以及半刚性基层沥青路面的水损害问题，近年来我国部分学者提出开级配大粒径沥青碎石混合料（Open-graded Large StoneAsphalt Mixes, OLSM），并将其作为裂缝缓解层设置在沥青面层的下面层，铺筑在带有裂缝（或接缝）的半刚性基层、旧水泥混凝土路面板或贫混凝土刚性基层之上。针对OLSM缓解层沥青路面的研究仍处于室内试验及试验路铺筑阶段。本文在已有研究成果的基础上，继续对OLSM的材料组成设计、路用性能进行试验研究，对OLSM缓解层沥青路面的细观结构及其宏观力学响应进行系统、深入地理论分析，在理论计算的基础上，结合试验段修筑情况，提出OLSM缓解层沥青路面结构的设计步骤及流程。本文以国内外OLSM参考级配为基础，应用变I法原理设计OLSM-25级配，结合空隙率（15%～20%）要求，提出OLSM-25推荐级配范围，通过试验研究其力学特性、高温性能、低温性能及水稳定性，提出OLSM-25技术指标。采用离散元方法，对AC-16、AC-20、OLSM-25的间接拉伸（劈裂）试验进行数值模拟；结合试验段修筑情况，建立设置OLSM-25裂缝缓解层的沥青路面离散元模型，在车辆荷载偏载作用下，对不同类型裂缝缓解层、不同级配OLSM-25裂缝缓解层的细观结构进行对比分析。采用有限元方法，建立设置OLSM-25裂缝缓解层的沥青路面有限元模型，对不同类型裂缝缓解层、不同级配OLSM-25裂缝缓解层的沥青路面进行应力分析及疲劳分析。在分析国内外沥青路面设计方法的基础上，考虑我国沥青路面存在基层开裂早期破坏的实际情况，提出OLSM缓解层沥青路面结构的施工建议、设计步骤及流程，推荐基于抗裂性能的OLSM缓解层沥青路面合理结构。通过研究表明：（1）在峰值轴向力作用下，当沥青混合料圆柱体试件开裂破坏时，随着沥青混合料公称最大粒径的增大，试件内部的微裂缝数量逐渐减少。与AC-16、AC-20相比，OLSM-25的间接拉伸抗裂效果显著。（2）在车辆荷载偏载作用下，当裂缝缓解层厚度相同时，OLSM-25裂缝缓解层底部A点颗粒的竖向接触力、竖向运动速度及竖向位移量均小于普通AC-25裂缝缓解层的对应值，OLSM-25裂缝缓解层的抗裂效果优于普通AC-25裂缝缓解层。（3）OLSM裂缝缓解层的耦合应力小于其荷载应力或温度应力；对于设置OLSM裂缝缓解层的刚性基层沥青路面结构设计，以OLSM裂缝缓解层的荷载应力或温度应力不超过其自身材料的容许抗拉强度作为设计依据，计算确定OLSM裂缝缓解层的合理厚度。（4）与相同厚度的普通AC-25裂缝缓解层相比，OLSM-25裂缝缓解层具有较高的承载能力和良好的应力消减及缓解性能；采用OLSM-25裂缝缓解层可有效减缓基层裂缝的扩展速率，显著提高沥青路面结构的疲劳寿命。（5）在实际工程应用中，综合考虑应力缓解效果、变形能力、减缓基层裂缝扩展速率、延长沥青路面疲劳寿命及施工中的离析问题等因素，选择材料组成相对偏粗、空隙率适中的2#级配OLSM-25作为裂缝缓解层，既达到缓解应力、减缓基层裂缝扩展速率的目的，又满足其路用性能要求，同时具有一定程度的变形能力，有效延长了沥青路面结构的使用寿命。更多还原

【Abstract】 In order to solve the problem of the reflective cracking in the semi-rigid base asphaltpavement, the asphalt overlay on old concrete pavement and the rigid base asphaltpavement, as well as the water damage problem of the semi-rigid base asphalt pavement,OLSM(Open-graded Large Stone Asphalt Mixes) relief layer has been put forward by someChinese scholars, it has been set below the asphalt surface layer and paved on the semi-rigidbase, the old concrete pavement, and the rigid base with cracks (or joints) in recent years inChina. The research on OLSM of asphalt pavement is still in the stage of the indoor test andthe test road construction. In this dissertation, on the basis of the existing research, thematerial composed design of OLSM and its road performance test have been continued, themesostructure and the macroscopic mechanical response of OLSM of asphalt pavementhave been thoroughly and systematically analyzed. On the basis of theoretical calculationsand combined with the test roads construction, the structure design steps and processes ofOLSM cracking relief layer of asphalt pavement have been proposed.In this dissertation, on the basis of the reference gradation of OLSM-25in the domesticand international, by using of the variable I principle, the gradation of OLSM-25has beendesigned. Combined with the requirements of the porosity (15%to20%), the recommendedgradation range of OLSM-25has been proposed. the mechanical property, the hightemperature performance, the low temperature performance and the water stability ofOLSM-25have been tested, and the technical specifications of OLSM-25have beenproposed. By using of the discrete element method, the numerical simulation of the indirecttensile (splitting) test of AC-16, AC-20and OLSM-25have been carried out. Combinedwith the test roads construction, the discrete element model of asphalt pavement structurewith OLSM-25cracking relief layer has been established. Under the action of theasymmetric traffic load, the comparative analysis of the mesostructure with two differenttypes of cracking relief layer, and the mesostructure with three different gradationsOLSM-25cracking relief layer have been carried out. By using of the finite element method,the finite element model of asphalt pavement structure with OLSM-25cracking relief layer has been established, the stress and fatigue analysis on asphalt pavement with two differenttypes of cracking relief layer, and three different gradations OLSM-25cracking relief layerhave been carried out. On the basis of the analysis of structural design method of asphaltpavement in the domestic and international, considering the actual situation ofearly-cracking destruction in the base of asphalt pavement in our country, the constructionrecommendations, the design steps and processes of OLSM of asphalt pavement structurehave been proposed. On the basis of the anti-cracking mechanism, the reasonable structureof OLSM of asphalt pavement have been recommended.The research indicates that as follows:(1) Under the action of the peak axial force,when the cylinder specimen of asphalt mixture is cracking, the number of micro-crackswithin the specimen reduces gradually. as compared with the AC-16and AC-20, theanti-cracking effect of the indirect tensile test of OLSM-25is significant.(2) Under theaction of the asymmetric traffic load, when two cracking relief layers have the samethickness, the vertical contact force, the speed of the vertical movement and the verticaldisplacement of A point particle in the bottom of OLSM-25cracking relief layer were lessthan the corresponding values of the ordinary AC-25cracking relief layer. The anti-crackingeffect of OLSM-25cracking relief layer is better than ordinary AC-25cracking relief layer.(3) The coupling stress is less than the traffic load stress and the temperature stress. For thestructural design of the rigid base asphalt pavement with OLSM cracking relief layer, itstraffic load stress or temperature stress should not exceed its own allowable anti-tensilestrength. On the above design basis, the reasonable thickness of OLSM cracking relief layerwill be calculated and determined.(4) Compared to the ordinary AC-25cracking relief layerwith the same thickness, OLSM-25cracking relief layer has higher carrying capacity andbetter stress relief performance. By using the cracking relief layer of OLSM-25, thepropagating speed of the reflective crack will slow down effectively, and the fatigue life ofthe asphalt pavement structure will be improved significantly.(5) In practical engineeringapplications, considering the stress relief effect, deformation capacity, slowing down thepropagating speed of the reflective crack, extending the fatigue life of asphalt pavement,and the mixture segregation problem in the construction, the2#gradation OLSM-25withrelative coarse aggregates and medium porosity should be taken as the cracking relief layer, not only the purpose of the stress relief effect, slowing down the propagating speed of thereflective crack should be achieved, its road performance requirements should be met and ithas a certain degree of deformation capacity, but also the life of the asphalt pavementstructure should be extended.更多还原