Little Theatre of Norfolk - Norfolk, VA
Challenge
June 2010 - The Little Theatre of Norfolk (LTN) was built in the early 1920’s and is the oldest continually operating community theatre in the nation, preparing to begin its 84th season. The structure is supported on deep pile foundations, but the interior floor slabs and non-load-bearing walls are supported on grade. A generalized soil profile identified with on-site test borings consists of fill soils over very loose to medium dense sand over very soft to medium stiff sandy clay over medium dense to dense sand. The medium dense to dense sand was encountered at depths ranging from 32 to 40 feet. Over the years, the interior floor slab settled from 1 inch to 13 inches, creating trip hazards and atypically-sloped floor conditions. The fixed auditorium seats leaned in the direction of the floor settlement. The floor movement was attributed to settlement of the upper fill layers and consolidation of the weak native soil beneath the weight of the fill soils and floor slab. Even with these unsafe conditions, the LTN was granted a special waiver to remain in operation so that profits could be used for the repair work and renovation. After 15 years, and with the assistance from special grants, the LTN finally was able to proceed.
Solution
JES Construction, Inc. (JES) was awarded the design-build project with the general scope of work to include; partial demolition of the existing concrete slab, installation of helical piles and a new structurally-reinforced concrete slab, construction of a new wheelchair seating area, and incidental carpentry repairs. Fifty-eight (58) helical piles were installed within the 45-foot by 60-foot auditorium. The pile configuration consisted of 2 7/8-inch OD by 0.203-inch wall round shaft with 8”-10” double-helix leads. The helical piles were installed to an average depth of 45 feet to support the design working load of 15 kips. The structural slab was detailed at 5 inches thick (3,000 psi) with No. 4 rebar at 12 inches on center each way and a maximum pile grid spacing of 8 feet. During the demolition phase of the contract, JES encountered unforeseen conditions in the lobby area and near the main stage. A 10-inch void was encountered beneath the lobby area floor slab and the foundation wall at the stage had settled approximately 1 inch. To resolve these unforeseen conditions, a contract modification was executed to install eighteen (18) hydraulically-driven slab piers in the lobby area and three (3) hydraulically-driven foundation piers at the main stage. The void beneath the pier-supported lobby slab was then filled with cement grout.
Project Summary
Geotechnical Engineer: McCallum Testing Laboratories, Inc.
Design-Build Contractor: JES Construction, Inc.
Certified Pile Installer: JES Construction, Inc.
Products Installed: (58) FSI Model 287 Helical Piles, 8”-10” Lead Section, Installed to an Average Depth of 45 feet, 15 kip Working Load; (18) FSI Model 288 Slab Piers Installed to an Average Depth of 40 feet and an Average Ultimate Capacity of 16 kips; (3) FSI Model 288 Push Piers Installed to an Average Depth of 40 feet and an Average Ultimate Capacity of 28 kips
