Abstract:

An interpretation method for advance geological prediction data of tunnel by ground penetrating radar (GPR) is put forward based on full waveform inversion, so as to learn the unfavorable geology ahead of tunnel face and guarantee the tunnel safety. Firstly, the typical unfavorable geological conditions are taken into consideration, numerical models for karst caves, fractures and broken zones are established, the forward simulation analysis is carried, and the forward simulation responses of GPR to typical unfavorable geology are summarized. And then, the optimal distribution of relative permittivity is obtained by using full waveform inversion to process the forward simulation data; the inversion results are analyzed and compared with the forward simulation data. The study results show that the relatively exact distribution of the relative permittivity in the prediction area can be obtained by full waveform inversion; the inversion results are consistent with the actual morphology of the unfavorable geological body, and the imaging results are better than the original GPR profile, which can improve the intuition and accuracy of the prediction of the unfavorable geological body.

Key words: tunnel construction, unfavorable geology, advance geological prediction, ground penetrating radar (GPR), forward simulation, full waveform inversion