High-resolution quasi-three-dimensional transient electromagnetic imaging method for urban underground space detection

Transient electromagnetic (TEM) method is a geophysical technique suitable for efficient detection of urban underground space, which can be used for advance detection of road collapse and underground water inrush accidents. In actual urban geological detection, engineers hope to be able to quickly characterize the underground space in 3-D, so as to assess the potential underground subsidence area or water inrush area risk. However, due to the complexity of urban geology, it is difficult for conventional 3-D imaging techniques to take into account both imaging efficiency and imaging accuracy. To address this issue, this article proposes a fast, high-resolution TEM quasi-3-D imaging strategy suitable for urban geology. We convert the TEM data into pseudoseismic wavelet data to identify the geological correlation of the 3-D spatial survey area, and then impose adaptive spatial constraints on the 3-D imaging. Simulation and application case results show that, compared with conventional imaging techniques, our proposed new strategy can effectively improve imaging resolution while ensuring computational efficiency. The research results provide a feasible technical solution for rapid high-resolution 3-D detection of urban geology.