Visualizing Drilled Shafts Using Sonar Caliper Methods

Generally visual examination of drilled shafts constructed under dry conditions provided the only reliable way to determine their shape. The shape of a drilled shaft becomes highly uncertain, however, when constructed under slurry-supported conditions. A mechanical caliper can provide limited information about shape under slurry conditions. Callipering such shafts using advanced sonar techniques now can provide much more information about shaft shape, volume and vertically. In addition Engineers now have more reliable way to assess strain gage data commonly used to determine the distribution of shear resistance at specific elevations along a shaft subjected to axial loads. The main value of sonar caliper technology to the geotechnical and foundation industry at large resides in its ability to improve quality assurance for clients/owners and quality control for drilled shaft contractors.