Enhanced Boulder Detection in Subway Construction through 3D Cross-Hole Electrical Resistivity Tomography

In subway construction, the presence of boulders can significantly impact excavation and tunneling processes. However, despite these challenges, an effective and reliable method for detecting boulders in advance has not yet been established. This paper presents a novel method for detecting and characterizing boulders using 3D cross-hole electrical resistivity tomography (ERT). The proposed technique involves the strategic deployment of multiple borehole electrodes, which work together to create a comprehensive three-dimensional resistivity model of the subsurface. This model allows for the identification and characterization of boulders, providing crucial information about their location and size. We demonstrate the efficacy of this approach in a physical flume experiment and a case study of subway construction, The findings from both the laboratory and field studies indicate that the 3D cross-hole ERT method is not only effective in detecting boulders and providing detailed information about their size and spatial distribution but also optimizes construction planning, reduces unexpected disruptions and additional costs, and enhances overall construction safety. The results highlight the potential of 3D cross-hole ERT as a valuable tool for geological assessments during infrastructure development.