ADOT put together a great little video embedded below that shows the construction of a drilled shaft foundation, or caisson as they are also known, for a bridge on the Loop 303 project in Surprise, AZ. The foundations shown are 88-feet deep and the rebar cage weighs in at about 20,000 pounds. The hole takes around 80 cubic yards of concrete to fill (that’s 8 concrete trucks). The video shows the fabrication of the cage, drilling the hole, and picking up and lowering the cage. My favorite part is the perspective of the video taken from the top of the cage as it is picked up and lowered, very cool. [Source: ADOT Blog]
Project Related
Drilled Shaft Rig Topples Over in Queensland, Australia
Fortunately nobody was seriously injured as a drilled shaft rig toppled over at a construction site in Maroochydore, Queensland, Australia. No word on what caused the accident at the building site. The operator was inside […]
Project Related
Launch Pit Retaining Walls Completed for SR 99 Tunnel in Seattle
Drilled shafts have been installed by Malcolm Drilling to form the secant pile retaining walls to support the 400 ft x 80 ft x 80 ft launch pit for the SR 99 tunnel boring machine […]
Failures
Drilled shaft rig falls into hole – Iowa
On May 15 a drilled shaft rig operated by Mid America Drilling Corp was nearly swallowed by the 9-ft diameter hole it was drilling for a cell tower foundation near Harlan, Iowa. Fortunately nobody was injured and the truck did not suffer any significant damage.
In Arizona, the standard of practice is to use a temporary surface casing to prevent dangerous failures like that. I once saw pictures of a drilling contractor superindendent almost get sucked into a collapsing shaft, even with the temporary casing. Pretty scary stuff. Source: Harlan Tribune. (Photo by Samantha Bruck)