内置应变传感器对沥青混合料力学性能的影响

Influence of built-in strain sensor on the mechanical properties of asphalt mixture

  • 摘要: 道路本体结构的智能智慧是道路工程发展的重要方向,内置应变传感器是实现路面结构应变感知的重要手段,为探究内置应变传感器对沥青混合料力学性能影响,运用离散元法,构建了内置应变传感器的沥青混合料细观模型,研究了应变传感器埋设深度和数量对沥青混合料力学性能影响,分析了沥青混合料材料公称最大粒径、级配和沥青砂浆黏结强度等对内置应变传感器工作性能影响. 结果表明:随着传感器埋设深度的增加,梁试件底部三个监测点位处水平拉应力分别增加56.9%、43.5%、43.8%,越接近梁试件底部,其内部水平应力场分布更均匀;与单传感器相比,埋设双传感器的梁试件裂隙增加速度更快,在挠度为0.8 mm时裂隙数便达到267个,单传感器仅为93个;沥青混合料公称最大粒径越大,力链数越少,AC-16、AC-20的平均力链比较AC-13分别降低4.9%、11.4%;沥青混合料级配越粗,荷载传递路径越少,接触力系数量减少77.7%,接触力分布均匀性降低,最大接触力增加74.6%,导致传感器工作稳定性越差;沥青砂浆黏结强度增加,最大接触力下降11%,传感器工作稳定性越好. 研究结果可为提升内置应变传感器的沥青混合料耐久性和工作稳定性提供参考.

     

    Abstract: The pursuit of intelligence and smartness in road infrastructure is critical for the advancement of road engineering. Embedded strain sensors serve as a vital tool for sensing strain within pavement structures. To explore the influence of these embedded strain sensors on the mechanical properties of asphalt mixtures, this study established a mesoscopic model of asphalt mixtures with embedded strain sensors using the discrete element method. The effects of embedment depth and quantity of strain sensors on the mechanical properties of asphalt mixtures were examined, and the impact of the asphalt mixture characteristics (such as nominal maximum particle size, grading, friction coefficient, and asphalt–aggregate bond strength) on the operational performance of the embedded strain sensors was analyzed. The results of the study show that as the embedment depth of the sensors (6 and 4 cm from the bottom of the beam) increases, the horizontal tensile stress at the three monitoring points at the bottom of the beam also increases by 56.9%, 43.5%, and 43.8%. This finding indicates that the closer to the bottom of the beam specimen, the more uniform the distribution of the internal horizontal stress field, which is conducive to the working stability of the sensors. The crack growth rate of the beam specimen embedded with double sensors is faster than that of the beam specimen embedded with a single sensor. When the deflection is 0.8 mm, the number of detected cracks reaches 267 for the double sensors and only 93 for the single sensor. Sensors should not be buried simultaneously in the middle and lower layers of the same point on the pavement. For the asphalt mixtures, large nominal maximum particle sizes (AC-13, AC-16, and AC-20) are associated with few force chains. Compared with that for AC-13, the average force chains for AC-16 and AC-20 are 4.9% and 11.4% lower, respectively, indicating an optimal nominal maximum particle size of 13.2 mm for the mixture. The coarser the grading, the fewer the load transfer paths, resulting in a 77.7% reduction in the number of contact force systems and a decrease in the uniformity of contact force distribution. Furthermore, the maximum contact force increases by 74.6%, leading to the poor operational stability of the sensors. An increase in bond strength (tensile strength and cohesion strength) reduces the maximum contact force by 11%, thereby enhancing the operational stability of the sensors. These outcomes provide a theoretical basis for elucidating the evolution of the service performance of pavement materials with embedded sensing devices.

     

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