Characterizing water-bearing structure ahead of tunnel using full-decay induced polarization based on the fuzzy C-means clustering method

The application of full-decay induced polarization offers additional potential to characterize water-bearing structures. The method enables inversion imaging of four parameters: zero-frequency resistivity, intrinsic polarizability, relaxation time, and frequency-dependent coefficient. Due to the inherent volume effect in electrical exploration, the inversion results often fail to accurately depict the scale of water-bearing structures. To address this limitation, we introduce the fuzzy C-means clustering constraint into the objective function of the full-decay induced polarization inversion. We propose a multi-parameter inversion method for full-decay induced polarization based on fuzzy C-means clustering. To address the inconsistent resolution of anomalies by each induced polarization parameter, we apply different constraints to the sensitivity matrix of each parameter, thereby balancing the resolution of anomalies across parameters. The four parameters are normalized to solve the problem of large order of magnitude gap between different parameters. Inversion imaging numerical simulations of typical water-bearing structures are carried out, and the results showed that the proposed tunnel full-decay induced polarization inversion method based on fuzzy C-mean clustering could effectively depict the position and morphology of the water-bearing structures. Additionally, an on-site application was carried out in the Yinchaojiliao Water Diversion Project, effectively identifying the water body in front of the tunnel face and guiding the on-site construction of the project. The tunnel full-decay induced polarization inversion method based on fuzzy C-mean clustering has the ability to locate and depict boundaries of water-bearing structures with high accuracy.