基于弹性波频谱特性的沉管隧道灌砂监测方法及应用

灌砂基础加固法在沉管隧道基础处理中应用广泛,然而复杂的施工现场及施工过程中的噪音会对监测产生干扰,故准确的灌砂实时监测方法一直是工程界所关心的重要课题。以多层层状介质中的弹性波传播特性为基础,通过对沉管隧道底板灌砂的全尺寸模型试验进行验证,建立基于弹性波频谱特性的无损监测方法。针对沉管隧道底板的水平层状介质模型,获得下部介质变化前后的弹性波响应波形数据,并对其进行波形频谱分析;同时在数据处理时,设定结构注砂变化前后的主频变化范围为滤波频带,进行滤波,降低施工噪音及复杂施工现场的干扰,从而通过工况变化前后的频谱响应差值进行施工进度实时评价。在理论研究的基础上,通过运用可视化窗口的观测结果与频谱监测结果的对比验证,建立响应频谱能量差与砂盘扩散半径、砂盘填充度的对应关系,采用可视化云图等手段,实时有效地监测基础施工的灌砂进度,为沉管隧道基础灌砂施工提供科学依据。

Application of a Sand-Filling Monitoring Method for Immersed TunnelsBased on the Frequency Spectrum Features of Elastic Waves

The sand-filling reinforcement method is widely used in the foundation treatment of immersed tunnels. However, noise during construction on complex sites will interfere with monitoring. The application and research of real-time sand-filling monitoring and detection methods has been an important issue in civil engineering. In this paper, based on the propagation characteristics of elastic waves in a multi-layered media, a non-destructive monitoring method based on the frequency spectrum characteristics of elastic waves was presented. With the full-scale model test of immersed tunnel sand filling, the response waveform of elastic waves before and after the change of lower media was obtained, and the frequency spectrum was analyzed. The horizontal layer dielectric model of the immersed tunnel was established to get the elastic wave response waveform data of the lower medium and waveform spectrum. The change range of dominant frequency of the structure before and after sand filling was set as the filter band to reduce the interference of noise on the construction site. The monitoring results obtained by the visualization window, and those obtained by the frequency spectra, were compared, and a visualization nephogram was adopted to real-time detect the sand-filling schedule of the building foundation. This research can provide the scientific basis for sand-filling construction of immersed tunnel foundations.