Abstract:

The geological conditions of the Qingdao Jiaozhou Bay subsea tunnel are complex, which include many groups of faults with a large dip angle, and therefore how to ensure the security of the tunnel in fault rich  water is a key problem in engineering construction. The application of geological radar  was introduced for detecting the fragmented rock and fissure water in F_4-5 waterbearing faults in the left line of the Jiaozhou Bay subsea tunnel. For the influencing factors during data gathering and data analysis,  some measures were used to reduce the interference, and the achievements such as pseudo-color survey line graph and survey line oscillogram were obtained. The achievements depict the growth scale, position and water situation of the F_4-5 fault. The parameter of the exact location and size of the fracture and the location of fracture and cracks in the fault zone were also provided. At the same time the geological forecast provided parameters for advanced grouting. The later geological compilation after the excavation confirmed the accuracy and validity of this geological radar forecast and the mentioned measures  certainly have reference mearing to ground penetrating radar application on subsea tunnels.

Key words:  JiaoZhou Bay subsea tunnel; ground penetrating radar; advanced geological forecast; water-bearing fault