Thursday, September 9, 2010

VT Academic and Student Affairs Building - Foundation Observations

The new Academic and Student Affairs Building at Virginia Tech is under construction just a short walk from the Department of Building Construction. What a great opportunity to observe the construction process from ground breaking onward. The finished building will include 77,301 finished square feet in 3 stories and will house two floors of dining and one floor of classroom space at a cost of just over $45,000,000. The schematic photos of the building show a green roof and rain gardens, leading me to the conclusion that cutting edge green technology was an integral part of the design process. Although construction is scheduled to take until summer 2012, I will be chronicling some of the important milestones as the foundations are constructed through December 2010.

  Figure 1 shows a nice overview of the project site layout, as McKinney Drilling Company prepares the deep foundation for the building. As the track drill uses a large auger to dig down to bedrock, a seperate crew is tying rebar cages that will be inserted prior to pouring concrete. If the caisson is deep enough, a steel sleeve will be inserted into the drilled shaft to prevent collapsing of dirt. At the same time, a track loader is busy digging out the next section of the site where caissons will eventually be drilled. These three activities, happening simultaneously, greatly increase the productivity on site.

Figure 1 - Drilling, Digging and Lifting
Figure 2 shows a rebar cage being lowered into a drilled shaft by crane. In the foreground, a rappelling setup has been installed above a drilled shaft. Before concrete is poured, a laborer is lowered to the bottom of the caisson to test-bore the rock and make sure it will provide a solid foundation. Talk about a dirty job!
Figure 2 - Lowering the Rebar Cage

Figure 3 shows the final step in preparing a caisson - the concrete. Here a truck is backed up to the drilled shaft and concrete is poured up to the desired level. In more difficult site environments it may be necessary to rent a pump-truck for this operation.

Figure 3 - Concrete Pour

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