Case Studies Case Studies: Neyland Stadium Bleacher Underpinning

Located in Knoxville, Tennessee, Neyland stadium is the fifth largest stadium in the United States and the seventh largest in the world. It was constructed on the University of

Tennessee campus in 1921 and is home to the Tennessee Volunteers football team. The lower west bleacher area was planned for removal in 2021 as part of a remodel to add club stadium seating to the lower field level. The bleacher removal would require excavation and construction of a soil nail wall to facilitate construction of a permanent wall system during a later phase of work. Prior to excavation activities, a portion of the upper bleacher sections would require underpinning. The only access for underpinning was beneath the bleachers which had limited overhead clearances. The underpinning system would also require brackets mounted on the vertical wall face of the concrete support beams for the existing stadium seating, which were located directly below the bleacher slab. Soil information was not available; therefore, an underpinning system that would allow verification of capacity at each pier location was desired. The underpinning and shoring system would be temporary since a new wall would be constructed adjacent to the soil nail wall.

Given the access limitations, lack of soil information and other project challenges, the Model 288 (2.875-inch OD by 0.165-inch wall) push pier system was selected as the optimal solution for underpinning at the bleacher location. Flushmount brackets were utilized to connect to the structure since they could be mounted to the vertical face of the support beams and installed in the low overhead area. The overhead clearance was so tight between the top of the brackets and the bottom of concrete slab, access holes were cored in the slab above each bracket location to facilitate set up of the drive stand and driving the pier tubes. The design required 17 push pier locations with service compression loads of 10 kips. A safety factor of two was specified for an ultimate capacity of 20 kips at each pier location. The piers were installed to a final drive force of 20 kips and the load was maintained for 10 minutes to verify capacity and monitor creep movement. The push piers were installed to average lengths of 32 feet. The underpinning was completed in 3 days.

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