沥青面层模量的检测与损伤分析

Modulus Detection and Damage Analysis of Asphalt Layer

为了合理分析沥青面层在重复荷载作用下的损伤发展过程,针对沥青面层进行了模量检测,采用沥青面层模量衰变量与沥青面层无损状态下模量的比值来反映损伤程度,并对该损伤随荷载作用次数的演化过程进行了分析研究。研究通过足尺加速加载试验来模拟重复的车辆荷载作用;采用落锤式弯沉仪(FWD)、便携式地震波路面分析仪(PSPA)和单轴压缩动态模量试验来获取非加载区沥青面层无损状态下的模量;采用PSPA来获得加载区沥青面层不同损伤状态下的模量;计算得到模量衰变量与无损状态下模量的比值;分析沥青面层的损伤演化过程,建立起沥青面层非线性损伤演化模型,对沥青面层各深度处损伤发展的快慢进行分析。研究结果表明:可利用S形模量主曲线将各试验所得的无损模量进行统一,现场检测手段获得的模量分析结果符合室内动态主曲线的预测结果;同时,损伤演化模型中的寿命因子可用于判断沥青面层损伤发展的快慢;对该参数进行归一化处理发现,轮迹带外边缘和轮隙中心在垂直于行车方向上的损伤随深度的增加而减缓,而在轮迹带其他位置和方向上,沥青层层中的损伤发展最快。借助所建立的非线性损伤演化模型,可为沥青层的损伤发展提供判断依据,并为优化养护时机和养护策略打下基础。

The modulus of an asphalt layer subjected to repeated loadings was measured to reasonably analyze the damage development therein.The ratio of the reduction in the modulus to the modulus of the undamaged asphalt layer is used to reflect the damage of the asphalt layer;the evolution of the damage with the number of the loadings was analyzed.Full-scale accelerated pavement testing was conducted to simulate the repeated vehicle loadings on the asphalt layer.Falling-weight deflectometer,pavement seismic property analyzer(PSPA),and uniaxial compression dynamic modulus tests were conducted to obtain the modulus of the undamaged asphalt layer in the unloaded area.PSPA was used to obtain the moduli of the damaged asphalt layers in the loading area;the ratios of the reduction in these moduli to the modulus of the undamaged asphalt layer were calculated.The damage development in the asphalt layer was analyzed,and a nonlinear damage-evolution model was established,which assisted in obtaining the speed of the damage development in the asphalt layers at different depths.It is found that the S-type master curve can be used to unify the undamaged moduli derived from the three tests.The results of the field-detection method are in accordance with the predictions obtained from the laboratory master curves.In addition,the regression parameter in the damage-evolution model assists in judging the speed of the damage development in the asphalt layer.The normalization result shows that the lateral asphalt layer at the outer edge of the wheel paths and that at the center of the wheel gap experience slower damage as the depth increases.The mid-depth asphalt layers at the other positions and directions experience faster damage.In conclusion,the nonlinear damage-evolution model can provide the basis for damage development judgment and lay foundation for optimizing the maintenance timing and strategy.