基于空隙空间分布特征的沥青路面渗水成因分析

An Analysis on Cause of Asphalt Pavement Permeability Based on Spatial Distribution Characteristics of Void

为探究沥青玛蹄脂碎石路面渗水成因,依托实体工程,分析了路面渗水系数与芯样空隙率之间的相关性。采用工业CT扫描并结合三维数字重构技术,研究了路面芯样内部空隙的空间分布规律,分析了路面不同深度处空隙的连通性,明确了结构层内部水的渗流路径。基于路面温度场有限元仿真技术并结合路面摊铺温度监测,进一步分析了结构层内部空隙非均态分布的原因。结果表明:玛蹄脂碎石路面现场检测渗水系数与芯样空隙率之间存在较好的指数关系;芯样内部空隙尺寸相对单一,单个空隙的等效直径约为2.02 mm,空隙多聚集于芯样两端,即沿路面深度方向空隙体积呈“由大变小、再增大”趋势;芯样顶端空隙的聚集现象,增加了空隙间的连通性,而连通空隙是导致路面渗水的直接原因,连通空隙率随路面深度的增加呈降低趋势,推断路面渗水形式以“水平渗水”为主;玛蹄脂碎石路面摊铺温度场有限元模拟结果与现场监测结果一致,即摊铺沥青玛蹄脂碎石结构层时,其内部热量向空气层、下承层中传递,导致结构层内部温度逐渐降低,且温度沿深度方向亦呈“由低到高、再到低”趋势;玛蹄脂碎石路面结构层内部空隙沿深度方向非均态分布,与路面碾压时不同深度处温度差异性有关。

In order to investigate the permeability cause of stone mastic asphalt pavement,the correlation between the permeability coefficient and the voidage of core sample is analyzed based on the actual project.Based on the industrial CT scanning and 3D digital reconstruction technology,the spatial distribution of void in pavement core sample is studied,the connectivity of void at different depths of pavement is analyzed,and the permeability path of water in the structure layer is defined.Based on the finite element simulation technology of pavement temperature field and pavement temperature monitoring,the reason of non-uniform distribution of voids in structure layer is analyzed.The result shows that(1)there is a good exponential relationship between the permeability coefficient and the voidage of core sample in the field test;(2)the internal voids of the core samples are relatively single,the equivalent diameter of a single void is about 2.02 mm,voids are mostly concentrated at the two ends of the core samples,that is,the voids volume along the depth of the road surface show the trend like“from large to small,then increase”;(3)the accumulation of voids at the top of core sample increases the connectivity among voids,and the connectivity voids are the direct cause of pavement permeability,and the connectivity voids decrease with the increase of pavement depth,it is concluded that the main form of pavement permeability is“horizontal permeability”;(4)the finite element simulation results of the temperature field of the martensite macadam pavement are consistent with the field monitoring results,that is,when the stone mastic asphalt layer is paved,the internal heat is transmitted to the air layer and the underlying layer,as a result,the internal temperature of the structure layer gradually decreases,and the temperature along the depth also presents a“from low to high,then to low”trend;(5)the internal voids in the structure layer of mastic macadam pavement are non-uniformly distributed along the depth direction,that is related to the temperature difference in different depth of pavement during rolling.