The use of borehole Ground Penetrating Radar in determining the risk associated with boulder occurrence

摘要

Determining the number of boulders that will be encountered in the tunnel envelope is one of the most difficult problems confronting the geotechnical engineer in the design of tunnels in glacial terrain. This issue is very important to the contractor, both in determining what method will be used to construct the tunnel and in determining the time that will be required for the chosen construction method. Borehole Ground Penetrating Radar (GPR) may provide a means to answer this difficult question. By using existing groundwater monitoring wells to access the tunnel horizon, and GPR antennas in a reflective mode to "sample" the material, enough volume could be sampled to give statistically significant result. This method is currently under development in conjunction with the design of a large diameter sewer tunnel in the Columbus Ohio area.