基于非均匀介质中瑞雷波频散特征的在役路基回弹模量反演研究

Resilient modulus of subgrade in service is one of the key parameters to evaluate the durability of the subgrade and pavement. However, the existing theory regarding the subgrade in service as the homogeneous elastic half-space inverts the resilient modulus average of the subgrade in service by surface deflection basin, which is difficult to be used for local quantitative and refined evaluation. Therefore, firstly, considering the inhomogeneous characteristics of the mechanical and physical parameters in the structure of subgrade in service under the actual conditions, an inhomogeneous half-space model which characterizes the structure of the subgrade in service and the Rayleigh wave excitation mechanism consistent with the traffic load condition are established, as well as the dispersion equation of Rayleigh wave theory in the structure of subgrade in service and the analytical theory of the wave field response and its calculation method. Afterwards, considering the influence of mechanical, physical and geometric parameters in the structure of each pavement layer, the finite difference numerical calculation and sensitivity analysis of the wave field response are carried out to reveal the characteristics of the Rayleigh wave dispersion in the road structure, in order to establish the extraction method of Rayleigh wave dispersion curve with main response component of directly perceiving the deformation of subgrade in service while avoiding the influence of the pavement structure. Finally, by extracting the Rayleigh wave dispersion curve, spatial inversion imaging of the resilient modulus field of subgrade in service is realized according to the theoretical dispersion equation, and is verified by the comparison tests. This project has important theoretical and engineering application value for the determination of the road operation and maintenance performance parameters and for the improvement of the corresponding test theory.

在役路基回弹模量是路基路面耐久性评价的关键参数之一。然而，现有理论将在役路基视为均匀弹性半空间，通过路表弯沉盆反演在役路基回弹模量平均值，难以用于局部定量和精细化评价。为此，本研究首先通过考虑实际工况下在役路基结构中力学与物理参数的非均匀特征，构建表征在役路基结构特点的非均匀半空间模型和与行车荷载工况相符的瑞雷波激励机制，建立在役路基结构中瑞雷波理论频散方程和波场响应的解析理论及其计算方法。然后综合考虑道路各层结构中力学、物理和几何参数的影响，进行波场响应有限差分数值计算和敏感性分析，揭示道路结构中瑞雷波频散特征，以此建立绕避路面结构影响直接感知在役路基变形为主要响应成分的瑞雷波实测频散曲线提取方法。最后通过提取瑞雷波实测频散曲线，按理论频散方程实现在役路基回弹模量场的空间反演成像，并结合对比测试予以验证。本项目对运维道路性能参数的确定和相应测试理论的完善具有重要理论和工程应用价值。

在役路基回弹模量是既有道面结构耐久性和稳定性评价的关键参数之一。为此，本项目基于瑞雷波在弹性层状体系中传播的动力理论，构建表征在役路基结构特点的层状半空间模型，揭示了瑞雷波在在役路基典型结构中的理论频散特征。基于瞬态显示动力有限元方法和高阶交错网格有限差分方法对在役路基结构模型的弹性波场响应进行了数值仿真，通过与传统F-K法、相位移法提取瑞雷波频散曲线进行误差对比，建立了高分辨率线性Radon变换的瑞雷波频散曲线提取方法。通过将线性Radon变换提取的频散曲线反演既有道面各结构层动模量的基础上，进一步对路基工作区细化分层，以此建立了在役路基工作区动模量的反演成像理论与方法，以此快速全面识别和研判在役路基结构动态力学参数的非均匀状态和隐患病害；在相应技术与应用层面，本项目开发了8通道阵列式高频面波测试装置和重复荷载作用下在役公路路基动态模量缩尺测试系统，通过在依托单位的室内足尺道路试槽内点对点依次进行瑞雷波、落锤弯沉仪、承载板和弯沉测试，建立了本项目研究方法和传统测试方法相应测试结果之间的相关关系；在以上基础上，本项目运用显式瞬态动力有限元揭示了弹性应力波在室内路基土体试件从从激发、传播到反射的全过程力学响应特征，通过频域分析方法开展了路基土的动态回弹模量与弹性波速之间的敏感性分析，据此建立了一种与瑞雷波测试现场在役路基结构回弹模量相辅的路基土动态回弹模量室内评价方法—冲击回波法，并与动三轴和杠杆压力仪对四种典型路基土填料进行了的对比测试与验证，至此实现了路基土力学设计参数与路基结构现场力学评定参数在测试机理、方法和技术上的协调与统一。本项目对运维道路性能参数的确定和相应测试理论的完善具有重要理论和工程应用价值。