Southern China (River-Crossing Tunnel)

  • Water depth: ~20 m
  • Alignment: 40 m beneath the riverbed, i.e. ~70 m below ground level
  • Hydraulic pressure: ~0.7 MPa
  • Geological conditions: Upper section mainly soft silt, silty sand, and sand–gravel; lower section composed of extremely high-strength rock (predominantly conglomerate, mudstone, and sandstone)