A precise and detailed knowledge and characterization of the subsurface is crucial for urban engineering planning and implementation. Drillings/boreholes are most widely used to provide the spatial distribution of blocks and boulders, but it is difficult to determine with high spatial-resolution location and distribution of the blocks and boulders in the soil stratum. We evaluate the applicability and the effectiveness of borehole Ground Penetrating Radar (GPR) for urban engineering purpose and we test attribute analysis to help the subway construction in the city center of Hangzhou, China. A multi-attribute approach exploiting amplitude-based and textural attributes is used. The results demonstrate that attribute analysis can visualize and quantitatively characterize borehole GPR features in an automatic and objective manner, maximizing the information for urban engineering. The integrated results from drillings and borehole GPR can provide an effective distribution of localized heterogeneities (such as blocks/boulders, sand/gravel lenses, cavities) in the potential target area.
