ABSTRACT
Tunnel boring machine (TBM) methods, including the slurry shield TBM and earth pressure balance (EPB) shield TBM, are employed based on ground conditions, resulting in the formation of an interface region in front of the TBM due to cutting tool rotation and additive injection. This study experimentally simulates electrical resistivity surveys in both types of TBM operations to identify the influence of the TBM-soil interface region on electrical resistivity exploration. A soil chamber containing silica sand and granite stone, along with an iron box model of a TBM, is used to replicate tunnel excavation while decreasing the distance between the TBM and the granite anomaly. Four electrodes are utilized to obtain electrical resistivity measurements at various distances for each case. After determining that the TBM model, acting as a conductor, has no effect on electrical resistivity, sodium bentonite slurry and foam are used to simulate the interface region created by the slurry shield TBM and EPB shield TBM, respectively. The experimental results show that the electrical resistivity survey in EPB shield TBM operations can identify geological risks, while anomalies are not discernible in the slurry shield TBM mode. In conclusion, the findings of this study provide valuable references for applying electrical resistivity surveys across different TBM modes.
