To provide a geological survey method and geological survey system capable of highly accurately acquiring a state of a natural ground on an upper side of a tunnel.SOLUTION: Hypocenter devices 21 and intra-tunnel geophones 25 are provided inside a tunnel 15 of a natural ground 10, and surface geophones 26 is provided on a surface 10a of the natural ground 10. Blast vibrations from the hypocenter devices 21 are received by the surface geophones 26 and the intra-tunnel geophones 25. A control unit of an analyzer acquires a first measured propagation time of transmitted waves of elastic waves propagated between the inside of the tunnel 15 and the surface 10a of the natural ground 10. The control unit acquires a second measured propagation time of refracted waves of the elastic waves propagated from the hypocenter devices 21 to the intra-tunnel geophones 25 installed inside the tunnel 15. The control unit surveys the state of the natural ground in which the tunnel 15 has been constructed, by tomography analysis using the first measured propagation time and the second measured propagation time.SELECTED DRAWING: Figure 1
展开▼
