Thermal contraction deformation behavior of asphalt mixture overlay with coordination of unbound aggregate layer
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 continuum-discrete 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 three-dimensional fabric change.A theoretical foundation for researching low temperature cracking resistant of asphalt pavement with unbound aggregate base layer can be improved.
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