ABSTRACT
WSP has developed a user-friendly photogrammetric mapping methodology focused on simplicity and availability, which in turn utilizes the Contractor’s presence on site. The methodology enables engineering geologists to remotely map tunnels and caverns, which reduces production time, increases safety, and improves the quality of as-built documentation.
Photogrammetry was used to more accurately map inaccessible tunnel and cavern roofs, correlate structures across parts of the facility and verify predicted weakness zones in the deterministic site model. Mapping results were further used to update hydrogeological calculations to verify the site’s suitability as a hazardous waste repository at 350 m depth. Turnaround time for photogrammetry-based geotechnical mapping was quick enough to use as active design to steer rock support for emerging benches in complex caverns. The entire site was mapped and documented with very high-resolution photogrammetry with just one camera used on seven concurrent excavation fronts.
Lessons learned included the need for a robust camera mount, sufficient lighting, ample computer storage, accurate control points and detailed planning. Planning is paramount to success and is facilitated by a simple, flexible methodology that can be utilized by the party who knows the schedule best: the Contractor. Communication with the Contractor avoids gaps or shotcrete-covered portions of the model. Industry’s focus on workplace safety has meant that the engineering geologist may not always have access to the mapping surface during construction. Remote mapping alleviates this challenge and allows the engineering geologist to do further interpretation at their convenience in a safer, calmer, quieter environment.
