基于分布式光纤的混凝土路面振动场感知与解析

Sensing and Analysis of Concrete Pavement Vibration Field Based on Distributed Optical Fiber

感知并解析路面振动可为智能车路系统提供健康诊断、定位循迹、风险预警等多功能服务,有效驱动路面智能化。通过优化分布式光纤器件设计与阵列布设,研发了水泥混凝土路面振动分布式感知系统;利用短时能量分析、功率谱分析等构建了振动时间-空间特征、频域-空间特征的场式表达方法;基于短时能量时空场、功率谱频空场,提出了水泥混凝土路面振动时空响应特征、全局频域特征的变维度解析方法;并于同济大学足尺试验场进行实测验证。结果表明:(1)荷载位置显著影响短时能量时空场,短时能量峰值坐标能灵敏地反映荷载位置变化,且相比线形光缆,由光纤环阵列组成的感知系统具有更高的空间分辨率(0.35 m);(2)相同荷载激振下,振动分布式感知系统与商用高精度加速度计测试结果相近(频峰识别误差小于1 Hz,空间振型置信度大于0.9),且在多点重复测试下具有较高稳定性;(3)面板模量显著影响功率谱频空场,模量越大前4阶频率越大,且增幅随阶次增高而愈发显著,该实测现象与理论分析吻合,且在6块板内测得相同趋势。该振动分布式感知系统能够准确、稳定地感知路面振动场时间、空间、频域信息;振动场变维度解析方法能够有效、可靠地解析时空响应特征、全局频域特征。

Vibration-driven services are an effective tool for smart roads, providing multi-functional services such as structural health monitoring, wheel tracking, and risk warning for intelligent transportation systems. The key is the sensing and analysis of pavement vibration. In this study, a distributed sensing system for vibration of a concrete pavement was developed by optimizing the design and layout of the sensing units based on distributed optical fiber. Analysis methods were proposed for space-time features and space-frequency features of the vibration field, using signal analysis methods such as short-term energy and power spectrum analyses. An analytical method for the vibration space-time response characteristics and global vibration characteristics was then proposed. Finally, a full-scale vibration test was conducted at Tongji University. Results showed:(1) The load position significantly affects the spatiotemporal distribution of the short-term energy. The coordinates of the short-term energy peak can sensitively reflect changes in the load position. Compared with a linear optical cable, the sensing system composed of an optical fiber ring has higher spatial resolution and positioning accuracy(0.35 m).(2) With the same load excitation, the distributed vibration sensing system has similar test results to commercial accelerometers(frequency error <1 Hz, modal assurance criteria >0.9), and shows high stability under repeated testing.(3) The elastic modulus of the concrete pavement slab significantly affects the global power spectral density field. The larger the modulus, the greater the natural frequencies of the first four orders, with the increase becoming more significant with increasing order. This trend agrees with theoretical analysis. The results indicate that the distributed vibration sensing system can accurately and stably measure the time, space, and frequency domain information of the concrete pavement vibration field. It also proves that the analysis methods for space-time response characteristics and global vibration characteristics of the vibration field are effective and reliable.