C+S March 2021 Vol. 7 Issue 3 (web)

sonnet Street for an extended period of time, as well as un- derground utilities, the team opted for a different, more traditional route: excavating the tunnel six inches at a time. This process proved time con- suming, taking the team six and a half months to complete while excavating the tunnel six inches at a time. Addi- tionally, in order to connect the two buildings, the tunnel had to change in elevation and offset horizontally. In order to achieve these parameters while also keeping a shape with a curved top, straight sides, and flat bottom the team opted to install a series of interconnected plates ap- proximately every six inches of excavating. To support this plate system, the team installed an I-beam approxi- mately every six feet and in- jected the system with grout.

Challenging this process was the high presence of water at the site. The team had to deal not only with rainwater, but also groundwater as the tunnel was constructed close to the water table in the area. They were able to overcome these challenges by using PREPRUFE 400T, which is a Grace Waterproofing Project. In order to account for the

thousands of anchor bolts being drilled through the waterproofing ev- ery day, McCarthy’s team met with manufacturers to come up with a plan of action. The result was a hand check of every seam and penetra- tion of the system to ensure proper installation. Once the system was fully completed, the team encountered no leaks. The months of excavating and tedious checking have paid off. Unlike most tunnels, this project has systems like mechanical, electrical, and lighting installed. More than just a pedestrian walkway and art gallery, the space and project have become a work of art of themselves, adding yet another dimension and element to one of the most storied public institutions in Texas.

LUKE CAROTHERS is the Editor for Civil + Structural Engineer Media. If you want us to cover your project or want to feature your own article, he can be reached at lcarothers@zweiggroup.com.


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