连续配筋混凝土刚柔复合式路面沥青面层开裂行为研究

The rigid-flexible composite pavement of continuously reinforced concrete with asphalt concrete overlay is the primary structure for pavement subjected to heavy traffic to achieve a long service life in China. The main distress is cracking which occurs in the asphalt layer. In this project, multi-scale laboratory tests and simulation analysis based on heat transfer, mechanics, materials science and other multi-disciplinary theory, combined with field investigation and testing of engineering projects are used to carry out research. Mechanical behaviors of rigid-flexible composite pavement of continuously reinforced concrete will be identified by coupled thermo-mechanical simulation. Nonlinear fatigue damage evolution and constitutive of asphalt layer will be studied. Characteristics of the damage evolution and inducement of cracking occurring at the bottom of asphalt layer will be investigated. Controlling index of cracking width of continuously reinforced concrete (CRC) slab for different asphalt layer thicknesses will be proposed. Testing devices for Top-Down fatigue cracking simulation of asphalt layer will be developed. Fatigue test, X-Ray computed tomography, 3D image restructure and the extended finite element simulation will be hired to reveal the cracking mechanism of Top-Down fatigue cracking and put forward the corresponding control methods. Material composition of asphalt layer and optimization of pavement structure and reinforcement ratio calculation will be developed based on the cracking control. Results can provide theoretical basis and scientific evidence for the improvement and development the design theory of asphalt layer.

连续配筋混凝土刚柔复合式路面是我国重载交通长寿命路面结构的主要发展形式，沥青面层开裂为其主要病害。项目根据传热学、力学、材料学等多学科理论，通过多尺度室内试验与仿真分析，并结合实体工程的现场调查与测试结果开展研究。拟通过热力耦合仿真分析确定连续配筋混凝土刚柔复合式路面结构的力学行为特征；通过沥青面层的非线性疲劳损伤演化行为及本构关系研究，探明沥青面层底部的损伤演化特性及开裂诱因，确定不同沥青面层厚度下CRC板缝隙宽度的控制指标；通过研发适用于沥青面层Top-Down疲劳开裂模拟的测试装置和开展疲劳试验，并结合X-Ray计算机断层扫描试验及图像三维重构、扩展有限元模拟，揭示沥青面层的Top-Down开裂机理并提出相应的控制方法；最后基于开裂控制确定沥青面层的材料组成、优化路面结构和配筋率设计方法。研究成果可为沥青面层设计理论的完善和发展提供理论基础和科学依据。

连续配筋混凝土刚柔复合式沥青路面是在连续配筋混凝土(CRC)上加铺沥青混凝土(AC)的长寿命复合式路面结构，开展AC层的开裂行为研究对提升CRC+AC复合式路面结构的耐久性和可靠性具有理论意义与实际价值。.通过项目研究，确定了连续变温条件下AC层厚度对CRC+AC复合式路面结构温度场的影响规律；基于温度和三向非均布车辆荷载耦合作用下AC层力学行为与开裂的分析，结合实体工程调研与跟踪观测结果，确定了CRC+AC复合式路面结构的力学行为与AC层开裂特征，推荐AC层的适宜厚度范围为8~12cm；给出了CRC+AC复合式路面结构设计时AC层厚度与材料性能、层间结合等因素协同考虑的建议。建立了AC层非线性疲劳损伤本构关系，基于移动荷载作用下AC层非线性疲劳损伤演化分析，确定了不利工况，探明了AC层的损伤演化行为特征及开裂诱因与过程；基于不利荷位下AC层疲劳损伤演化规律分析，推荐了正常行驶路段及收费站、服务区入口等路段AC层的厚度设计值；确定了不同AC层厚度下CRC板裂缝宽度的控制值。.研发了适用于刚柔复合式路面AC层Top-Down开裂模拟的试验装置及方法；基于双模量三维损伤本构的AC层疲劳损伤分析，确定了AC层表面非线性疲劳损伤演变规律及损伤度预测经验公式，结合Top-Down开裂模拟试验、Top-Down裂缝疲劳扩展规律、实体工程观测结果，揭示了AC层的Top-Down 开裂机理，确定了AC层Top-Down开裂控制指标及标准，建议AC层厚度不低于8cm，拉压模量比应控制在0.7左右。基于不同AC层厚度下CRC板的微裂缝宽度控制指标，结合现行行业规范优化了CRC+AC复合式路面的纵向配筋率设计方法，给出了随AC层厚度增加纵向配筋率的折减规律；确定了AC层厚度、微裂缝宽度等对AC层力学响应的影响规律及敏感性排序；优化了CRC+AC复合式路面的结构组合、CRC板配筋方式、混凝土材料组成等；确定了基于AC层抗裂和抗变形能力提升的沥青混合料材料组成。.研究成果可为CRC+AC复合式路面设计理论与方法的完善和发展提供理论基础和科学依据，对CRC+AC复合式路面推广应用起到促进作用。