Abstract: The authors introduce the geophysical prospecting techniques used in the entire life cycle of tunnel engineering, and analyze the application effects of geophysical prospecting techniques in the feasibility study stage and design stage of shield tunnels in urban rail transit, the construction stage of mining tunnel in regional railway, the completion acceptance stage and the operation stage of diversion tunnels, so as to systematically analyze the merits and defects and applicability of geophysical prospecting techniques used in each stage of tunnel engineering. The application results reveal the following: (1) In the feasibility study stage of river-crossing tunnel, sub-bottom profile and shallow reflection seismic method achieve good prospecting results, providing engineering geological basis for proposed tunnels. (2) In the tunnel design stage, the integrated geophysical prospecting technology combining microtremor survey method and high-density resistivity method, supplemented by a few geological drilling holes, can identify the depth and undulation patterns of bedrock surfaces, as well as the location and development direction of the fault fracture zone along the tunnel with the burial depth within 30 m. (3) In the advance geological prediction stage during tunnel construction, the ground penetrating radar method is highly accurate in predicting the water-rich and weak interlayers in front of the tunnel face. (4) Some geophysical prospecting techniques have good application effects in tunnel completion acceptance and operation stage, like the ground penetrating radar method for concrete lining detection, the impact echo method for steel lining detection, and the ultrasonic-rebound combined method for concrete strength detection.

Key words: geophysical prospecting techniques, tunnel engineering, entire life cycle, reflection seismic method, multiple wave, microtremor detection, ground penetrating radar