In addition to conventional geotechnical face mapping, PSM applied their in-house photogrammetry capabilities to generate complete 3D reproductions of the excavations. This allows further review of the encountered ground conditions even after primarily shotcrete support has been applied to the face.
The image-capturing process requires less than 10 minutes to complete in the field ensuring minimal production delays. Survey data acquired as part of the excavation process is used to scale and georeference the models.
The example below illustrates a model cross passage excavation between the two TBM tunnels.