疲劳加载对沥青混合料SMA-13渗透特性的影响分析

THE ANALYSIS ON EFFECT OF FATIGUE LOADING ON PERMEABILITY OF ASPHALT MIXTURE SMA-13

为了揭示交通荷载下沥青混合料的渗透特性演化规律和水损害机理,本文针对SMA-13沥青混合料,利用马歇尔击实和旋转压实两种成型方法分别制备出4种空隙率(4%、6%、8%、10%)的圆柱形试件,进行三轴疲劳加载试验,利用自研的多场耦合条件下路面材料渗透性测试系统,测试并比较在不同疲劳阶段试件渗水系数随水压(0.04 MPa、0.10 MPa、0.18 MPa、0.26 MPa)和轴压(0.7 MPa、0.9 MPa、1.1 MPa)的动态变化。结果表明,疲劳加载对试件渗透性能的影响具有压密和损伤双重作用,低空隙率试件的渗水系数主要受持续的疲劳损伤作用而增大,高空隙率试件的渗水系数主要受压密作用而随着疲劳加载逐渐降低。空隙率是影响沥青混合料渗透性能的关键因素,高空隙率试件的渗水系数显著高于低空隙率试件的渗水系数。渗水系数随水压的增加而增大,渗透性较弱的试件受水压的影响更为显著。渗水系数随轴压的增大整体呈现减小的趋势,但与空隙率和水压相比,轴压的影响相对较弱。过高的动水压力会导致空隙率6%左右的沥青混合料渗水性能显著增强,易产生水损害破坏。旋转压实与马歇尔击实成型试件的渗水系数随疲劳加载、水压和轴压的变化规律相似,后者一般大于前者。

In order to reveal the permeability evolution law and water damage mechanism of asphalt mixture under traffic load,cyclic triaxial tests on cylindrical specimens with air void of 4%,6%,8%and 10%formed by Marshall and Gyratory compaction method were carried out aiming at SMA-13 asphalt mixture.The dynamic changes of permeability coefficients of specimens with water pressure(such as 0.04 MPa,0.10 MPa,0.18 MPa and 0.26 MPa)and axial pressure(such as 0.7 MPa,0.9 MPa and 1.1 MPa)were tested and compared in different fatigue period by using a self-developed permeability test device on pavement material under the multi-field coupling condition.Results show that fatigue loading has both compaction and damage effects on the permeability of specimens,permeability coefficients of low porosity specimens increase under sustained fatigue damage,while permeability coefficients of high porosity specimens decrease under compaction with the progress of the fatigue loading.Air void is a key factor affecting permeability of asphalt mixture,the permeability coefficients of the specimens with high air void is higher than that with low air void.The permeability coefficient increases with the increase of water pressure,the effect of water pressure is more obvious when the permeability of specimen is weak.The permeability coefficient presents decreasing trend on the whole with the increase of axial pressure,but the effect of axial pressure is weak compared with air void and water pressure.Exceedingly high water pressure can significantly enhance the permeability of asphalt mixture with air void of 6%,which leads to water damage easily.The change regularities of permeability coefficients of specimens formed by Marshall and Gyratory compaction methods with the change of various parameters such as fatigue loading,water pressure and axial pressure are similar,but the latter is greater than the former in general.