Abstract: To accurately find out the cause of gradation segregation of asphalt mixture in paver screw conveyor and improve the pavement quality, the velocity and force models of the mixture under the action of the screw conveyor were firstly established, based on the screw conveying mechanism. And the dynamic characteristics of mixture in the conveying process were studied．Secondly, the distribution rule of aggregates with different particle sizes along the radial and axial direction of the spiral blade was analyzed, and the influence of the support hanger on the uniformity of the mixture transportation was studied. Finally, asphalt mixture pavement sampling and extraction screening test were conducted to verify the theoretical analysis conclusions. The research results show that the structure and operation parameters of the screw conveyor will affect the asphalt mixture distribution uniformity．The mixture axial velocity increases gradually from the center of screw blade along the radial direction．The average size of aggregates in the inner ring of screw blade are smaller than these in the outer ring. Fine aggregate easily tends to aggregate and segregate in the initial stage of the screw conveying process, and the segregation degree gradually weakens along the conveying direction. Coarse aggregate will aggregate and segregate after passing the critical point. The segregation degree is the largest at the support hanger area, which is manifested as coarse aggregate accumulation and segregation. The gradation test of asphalt mixture is consistent with the conclusion of theoretical analysis.

Key words: highway engineering; screw conveyor; asphalt mixture; paving segregation; gradation test

摘要： 为了准确掌握沥青混合料在摊铺机螺旋处的级配离析原因，提高路面铺筑质量，基于螺旋输送机理，首先建立了混合料在螺旋布料器作用下的速度和受力模型，研究了输送过程中的混合料动力学特性；其次分析了不同粒径的骨料沿螺旋叶片径向及螺旋轴向的分布规律，并研究了支撑吊架对混合料输送均匀性的影响；最后进行了沥青混合料路面取样及抽提筛分试验，以验证理论分析结论。研究结果表明：螺旋布料器的结构和运转参数影响了沥青混合料的分布均匀性，混合料的轴向速度从螺旋叶片中心沿径向逐渐增大，且靠近螺旋叶片内环的骨料平均粒径偏小，外环骨料平均粒径偏大；在螺旋布料起始段易出现细骨料聚集离析，且离析程度沿布料方向逐渐减弱，通过临界点后会出现粗骨料聚集离析；支撑吊架位置离析程度最大，且表现为粗骨料聚集离析。沥青混合料级配试验与理论分析结论相一致。

关键词: 道路工程；螺旋布料器；沥青混合料；摊铺离析；级配试验