Abstract: Accurate identification of rocksoil types and their spatial distribution is essential for ensuring construction safety and controlling project costs in urban metro tunneling. Along the Wuhan Metro Line 5 alignment between Pengliuyang Station and Simenkou-Yellow Crane Tower Station, the tunnel must pass beneath She Shan, where extremely hard quartz sandstone is present, and the area is densely built0up with urban structures. After reviewing existing data and consulting specialists, it was determined that conventional borehole drilling could not be fully implemented across the entire section. Therefore, on the basis of detailed geological mapping, a suite of integrated geophysical prospecting methods—including ground-penetrating radar, electrical profiling, and transient electromagnetic sounding—was employed to investigate the distribution of hard rock beneath the densely built urban zone. Comparison with field geological mapping and earlier investigation results indicate that the integrated geophysical survey provides reliable outcomes. The total tunnel length affected by hard rock is approximately 131.8 m. Laboratory testing shows that the uniaxial compressive strength of the hard rock ranges from 153 to 260 MPa, with quartz content reaching 99%. It is recommended that the mining method be adopted for tunnel construction between chainages K11+597 and K11+701.8. In the subsequent section from K11+701.8 to K11+728.8, where self-stability is relatively weaker, roof support should be installed.

Key words: Integrated Geophysical Investigations, Densely Populated Area, Hard Rock, Subway Tunnel