Abstract:

Unexpected geological disasters such as faults, karst caves, water and slurry gushes often happen during tunnel construction, which can bring momentous disaster and un-estimated economic loss to construction. The precise and immediate forecast in advance about geological conditions in front of the tunnel face has an important practical value in engineering. As a variation of the seismicreflection method, the land sonar method is a kind of advanced geology prediction method ahead of the tunnel face. Compared with ordinary detection methods， this method hasmany merits such as high resolution ratio，avoiding lots of disturbed waves，continuous collection for single trace， high energy of reflection waves and minimum offset distance. Based on the detailed investigation of engineering geological conditions along a tunnel, the land sonar method was applied to detect  faults and karst caves in front of the tunnel face. The results show that the land sonar method has a high accuracy to find faults and karst caves, which can also be an assistant method to the water detection.

Key words: land sonar method; advanced geology prediction; tunnel; seismic exploration