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]
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)
Geologic Hazards
US 89 Bitter Springs Landslide Video Updates
Since I last posted about this landslide, ADOT has added several videos to their YouTube channel. It’s clear that this highway is going to be closed for the long term. ADOT and their on-call geotechnical consultant tasked with this project, Kleinfelder, are currently drilling boreholes to attempt to characterize the failure surface and determine what the geometry of the failure surface is. They are installing at least 10 inclinometers to try to determine the location of the slip plane or planes at depth and they have two extensometers to measure if any additional movement occurs. They are also performing LIDAR surveys as well. Check out the videos below.
Initial ADOT Video Describing the Failure
Click through for the videos!
Project Related
Bauer will construct foundations for 1-km tall Kingdom Tower in Saudi Arabia
The Kingdom Tower to be built in Jeddah, Saudi Arabia will be 1,001 meters tall when completed in 2018. It will be the first building taller than 1-km and 173 meters taller than the Burj […]