ABSTRACT
It is crucial to predict hazardous ground conditions ahead of a Tunnel Boring Machines (TBMs) for stable tunnel construction. In this study, a laboratory chamber test was conducted to simulate the electrical resistivity and Induced Polarization (IP) surveys during the TBM advancement toward risky ground conditions in a soil chamber. In addition, risky geological conditions (i.e., the typical zones of fault, geologic transition, and embedded core-stone) possibly encountered during tunnel excavation were modeled in the soil chamber. The electrical resistivity and chargeability were simultaneously measured at the tunnel face of the model during tunnel excavation. The guideline on accurately predicting various hazardous conditions was proposed by analyzing the variations in resistivity and chargeability measurements during TBM advancement in the experiment. In conclusion, a hybrid method simultaneously implementing the electrical resistivity and the induced polarization surveys can predict hazardous ground conditions ahead of a tunnel, which enables efficient and stable tunnel excavation by minimizing potential risk in advance.
