Abstract: It is one of the most important tasks in the geological investigation of the proposed river crossing tunnel of Wuhan Metro Line 7 to evaluate the location, occurrence, scale and width of the active faults, especially the Holocene active faults, and their impact on the project in detail. The feasibility of the shallow seismic reflection method in water area is verified by the numerical simulations. Through the combination of the shallow seismic reflection wave method and the geological drilling method, the range and depth of the geological fault zone in the proposed rivercrossing tunnel of Wuhan Metro Line 7 are able to be determined, and the boundary between the overburden and the bedrock is divided. The integrated investigation results show that: (1) the F9 fault zone has obvious wave group absence in the reflection timedistance profile, and has the good response characteristics, which corresponds well with the regional geological structure. The location, occurrence and depth of the fault can be inferred; (2) The geophysical characteristics of the overburden layer and the bedrock are distinctly distinguished. After the drilling sampling, the interface of the reflection wave group corresponds well with the interface of the overburden layer and bedrock; (3) The tunnel barrel passes through the overlying loose sand layer, so the fault has no effect on the project.

Key words: metro site investigations, river crossing tunnel, fault, seismic reflection method, integrated investigation methods