客运专线无砟轨道路基面防水型沥青混合料指标体系与配制技术

Mixing Design and Application of Impermeable Asphalt Mixture in Subgrade Surface Layer of Ballastless Railway Track Substructure

在分析无砟轨道路基面防水层功能要求和沥青混合料水力行为的基础上,提出适合客运专线无砟轨道技术要求的路基面防水型沥青混合料SAMI(surface asphalt mixture impermeable)的指标体系。通过大量的马歇尔试验,研究影响SAMI混合料渗透性能的因素如空隙率、沥青含量、级配组成和最大公称粒径,提出路基面防水性沥青混合料的建议技术标准。试验表明,SAMI-10可以作为客运专线无砟轨道路基面防水层的主型设计方案。提出路基面防水型沥青混合料应考虑温度分区,在进行SAMI混合料设计时,应以渗透系数和空隙率作为控制指标,以马歇尔稳定度、冻融劈裂强度比和低温收缩系数作为优化指标。并以SAMI-10为例,给出路基面防水型沥青混合料的配制技术。

The subgrade surface has to be designed with the impermeable layer to protect subgrade soils and succeeding layers from erosion and moisture influence to produce a sound ballast substructure for high speed passenger lines. Based on comprehensive literature review, field investigation and laboratory tests, design specifi- cations for hot mix asphalt used in the subgrade surface are proposed in this paper. Various factors influencing permeability behavior of asphalt mixtures such as the air voids, asphalt content, aggregate gradation and nominal maximum aggregate size are explored and the standards of the SAMI （surface asphalt mixture for impermea- ble usage） layer in subgrade design are outlined. Research results show that the coefficient of permeability and voids in total mix should be used as the governing parameters and the Marshal stability, tensile strength ratio and coefficient of low-temperature contraction should be used as the optimizing parameters in the design of SAMI mix. Finally, SAMI 10 is proposed to be the major type in design of the subgrade surface layer and the mix design methodology is demonstrated.