C+S November 2021 Vol. 7 Issue 11

vide the tunnel shape, tunnel bottom, driving box, and a numbered position marker for tunnel orientation. Once a section has been blasted or dug out, De Vuyst positions the SX12 and captures a full-dome scan to collect a georeferenced point cloud of the 60-m area. She integrates that data into TBC and using the software’s specialized Tunnel module, she uses a classification tool to automatically clean and process the data to create a tunnel shape––a process that takes 3 minutes per scan. “The scanner captures everything it sees — people, cars, even water droplets –– as well as the tunnel shape,” says De Vuyst. “Without the automatic classification tool in TBC, I’d have to manually select each bit of noise and delete it. That feature, along with the automatically georeferenced scans, saves me hours of processing time. And because I know I can eliminate noise automatically, I don’t worry about passing traffic or objects in the way.” Once she has the tunnel shape, she can combine survey controls with the density of points to calculate and verify earthwork volumes as well as convert the 3D model to a tunnel profile drawing, indicat- ing precisely where more sediment needs to be removed and how much. Digger operators then use the prints in their cab as a machine control guide. “I make profile prints of the tunnel at every half meter,” says De Vuyst. “That allows everyone to monitor progress at set intervals. Crews can not only see how the tunnel looks now, I can provide his - torical views to show how the tunnel looked a week ago or even at the beginning of construction. It’s incredibly helpful for measuring and monitoring progress.” The ability to efficiently produce tunnel profiles was particularly ben- eficial for preparing and positioning Maursund’s technical building, which is set in the tunnel center, 93 m below sea level. Teams needed to blast out a space 5 m deep by 20 m long. Precision was paramount because the building’s pre-fabricated construction was designed to within only a half-meter of the tunnel wall and the top of two of the building’s corners. De Vuyst used the SX12 to as-built and calculate the excavation volumes based on two profile prints for the same area to ensure the space was correct. In early June, crews suc - cessfully constructed the technical building. Locked and bolted In addition to checking and calculating volumes, De Vuyst has also been consumed with bolts––prism bolts, reinforcement bolts, lighting bolts, and signage bolts, all of which she has either been taking as- builts of or setting out. Of the roughly 170 bolts she has set out, the most challenging to pre- cisely position were the bolts for road signs that will be installed in the tunnel. The bolts needed to be set at a minimum height of 2.2m above the finished road but at the time, a ditch for underground cables had been dug, making access to properly mark the positions difficult. De Vuyst resolved this with the SX12’s green laser and a truck with a hydraulic bed.

With a tunnel shape model as a base, she used the defined design plans and national height specifications to determine and draw set-out lines indicating where the bolts should be placed. She then imported that 3D file into the TSC7’s Access software. Setting up the SX12 about 20 m from the truck, she used the set-out function and let the scanner’s green laser navigate to the corresponding line. From there she used the controller to move the laser along the line until it hit the precise break point. The person on the truck could then mark the tunnel ceiling at the exact bolt position. “The clarity, precision and range of the green laser made the task so much easier,” says De Vuyst. “Even at 100 meters away, points are crystal clear.” With one kilometer of the Maursund tunnel now complete with in - stalled bolts, reinforcement materials, concrete fire protection, and 8.5 billion 3D points, De Vuyst will continue to do more of the same for the last half of the Maursund and the full length of the Kågen to meet the completion deadline of fall 2022. De Vuyst may still not know what to expect as work continues, but she’s confident the versatility of the SX12 will light the way.

MARY JO WAGNER iis a Freelance Writer, Editor, and Media Consultant based in Vancouver, BC. She can be reached at mj_wagner@shaw.ca.

45

November 2021 csengineermag.com

Made with FlippingBook Annual report