基于排水沥青混合料细观结构的排水特性分析

Analysis of Drainage Characteristics Based on Microstructure of Porous Asphalt Mixture

对连通空隙结构对排水沥青混合料渗水特性的影响进行了研究,基于工业CT获取排水沥青混合料空隙细观分布特征,建立了排水沥青混合料的渗水数值模型,并采用有限体积法分析水在排水沥青混合料结构内部的流动特征,探讨连通空隙直径、空隙弯曲度与最小截面尺寸对水流特性的影响.结果表明:空隙直径对水流流速的影响较大,流速近似与空隙直径的平方成正比;空隙弯曲度越大,流速与流量越小;弯曲结构形式对流速与流量的影响较小,分析过程中可忽略空隙弯曲结构形式,只考虑弯曲度的影响;以连通空隙路径中的最小截面直径作为整个水流路径的当量直径来进行渗水特性分析,会造成计算的渗透系数偏小,需采用一定的修正关系式对计算结果进行修正.

In this paper, the influences of connecting air voids on the seepage characteristics of the porous asphalt mixture were investigated ; the micro-distribution characteristics of the porous asphalt mixture is discussed based on industrial CT; a seepage-flow numerical model of the mixture is established ; the internal flow characteristics of wa- ter within the porous asphalt mixture is analyzed by using the finite volume method; and the water flow characteris- tics affected by the diameter, the tortuosity and the minimum sectional size of the connecting air voids are dis- cussed. The results indicate that （ 1 ） the air void diameter greatly influences the flow velocity and the velocity is approximately proportional to the square of the void diameter; （2） the larger the tortuosity is, the smaller the ve- locity and the flow are; （3） as the bending structure has little influence on the velocity and the flow, it can be neglected and the tortuosity is solely taken into consideration; （4） if the minimum sectional diameter of the con- necting air voids is taken as the equivalent diameter of the whole water path for analyzing the seepage characteri- stics, the calculated permeability coefficient may be smaller than the actual value, so that a revision is necessary.