The Cal GeoWall team is ticking off the remaining challenges in its competition model. Mid-Pac is less than 2 weeks away.
This year the team needed to design and build a model mechanically stabilized earth (MSE) retaining wall and a load frame, from which a bucket is hung.
The bucket hangs out over the edge of the wall, and is filled with 60 lbs. of sand. The front of the wall consists only of a piece of poster board, yet it can hold back hundreds of pounds of sand, as well as the load from the bucket.
How can the poster board be strong enough to withstand this load?
"It is because of the many thin, kraft paper strips that attach to the poster board and extend into the sand," said Robert Spragg, the team's Project Manager, "The paper strips provide a strong anchor for the wall."
If GeoWall succeeds in having the lightest load frame with the smallest amount of reinforcement—that does not fail or deflect too much—it wins!
In February, the team competed in the national competition in Phoenix, AZ.
During the competition, Berkeley realized that its load frame experienced too much deflection.
Thus their focus shifted to making a new frame that is more sturdy and bends less.
At right, some GeoWall members at Phoenix competition.
Their new load frame design (which is a secret until after the competition) enables the frame to support more weight while minimizing deflection.
The team's biggest challenge is fabricating the load frame, especially because for the first time in competition history, the frame must be made out of wood.
The upside of creating a load frame is that the team learned how to use of many of the machines in the Davis Hall Machine Shop.
"This has been a great experience! We learned practical skills, such as how to use a lathe, drill press, and sander," said Spragg.
GeoWall's final challenge is to optimize the paper reinforcement strips.
Go Cal GeoWall!
Go Bears!