级配碎石层协调沥青混合料层温度收缩变形行为

Thermal contraction deformation behavior of asphalt mixture overlay with coordination of unbound aggregate layer

为揭示级配碎石基层与沥青混合料面层的温度收缩协调变形规律,本文采用动静态应变采集系统实时获取沥青混合料层的温缩应变,基于PFC6.0 Suite和FLAC3D构建了组合结构连续-离散耦合模型,探究了级配碎石层与沥青混合料层温缩协调变形宏观和细观响应规律。研究结果表明:连续-离散耦合模型与室内试验的吻合度相比连续介质模型高,温缩系数相对误差最大为8.1%;沥青混合料及其组合试件温缩应变-时间关系曲线均呈先快后慢的非线性变化规律,沥青混合料类型及降温温差对级配碎石的约束作用基本无影响;组合试件温缩变形主要发生在前1 h内,沥青混合料层整体由“翘起”状逐渐过渡到“平缓”状;级配碎石层通过颗粒向内挤压运动,使两端松散膨胀及颗粒接触重组来实现与沥青混合料层的协调变形。本文从宏观应变响应与空隙率、配位数及三维组构细观响应揭示温缩协调变形机制,研究结果可为级配碎石基层沥青路面低温抗裂研究提供理论参考。

To reveal the coordinated deformation mechanism of temperature shrinkage between unbound aggregate base layer and asphalt mixture overlay,the dynamic and static strain acquisition system was adopted to obtain the thermal contraction strain of asphalt mixture layer in real time.And the continuumdiscrete coupling model of composite structure was constructed based on PFC6.0 Suite and FLAC3D software.The macro-and meso-response law of unbound aggregate layer and asphalt mixture overlay were investigated.The results show that the continuous-discrete coupling model has higher consistency with the laboratory test than the continuum model,and the relative error of temperature shrinkage coefficient is 8.1%.The thermal strain-time curves of asphalt mixture and its composited specimens exhibit a nonlinear change law of first fast and then slow.And the asphalt mixture types and cooling temperature differences have little effect on the constraint action of unbound aggregate layer.The temperature shrinkage deformation occurred within the first hour,where the asphalt mixture layer gradually changed from"warp"to"gentle".The coordinated deformation between unbound aggregate base layer and asphalt mixture layer can be realized by particle contact recombination,the inwardly extruded movement of particles,loose on both ends and the middle compaction.In this paper,the coordinated deformation mechanism of temperature shrinkage was revealed from the macroscopic strain response,voids,coordination number and threedimensional fabric change.A theoretical foundation for researching low temperature cracking resistant of asphalt pavement with unbound aggregate base layer can be improved.