Groundbreaking research plant

The Goal

To build a below-ground facility for antimatter research
A group of researchers will send a beam of neutrino particles underground and across 810 kilometers from their laboratory in Illinois to the woods of northern Minnesota. The beam – travelling at close to the speed of light – will end in the NOvA Far Detector plant, where the properties of the particles will be examined. The new facility therefore needed to be built underground and with extra shielding to create a safe area for the research.

The Project

Summary:
The large embedded enclosure for the research facility was built 12 meters below grade in granite rock, with composite precast and in-situ construction.

The Solution

1. Strong technical solutions
   For scientific reasons, the NOvA Far Detector plant is secluded and its enclosure needed to be embedded 12 meters below grade in rock. The 3,800m² detector enclosure was 106 meters long, 21 meters wide, and 21 meters high. The concrete floor slab and walls needed to be cast in-situ, while the roof was a composite construction of precast concrete planks with a cast in-situ concrete topping. Cosmic ray shielding would then be provided by a 15-centimeter-deep barite aggregate layer. The enclosure included support facilities such as computer, control, and electrical equipment rooms.To build the enclosure required a single-sided pour against the rock face after the base slab was poured. The large scale of the pour required formwork that was not only strong enough to withstand the high concrete pressure, but was also durable enough for a project of this duration.

   At 12 by 8 feet, MEVA’s heavy-duty Imperial wall formwork not only offers the largest sized panel of any modular system, it also takes the most concrete pressure with a capacity of 2025psf. In addition, the alkus all-plastic facing in all MEVA formwork panels is resistant to UV rays, is impervious to water, climatic influences, heat or cold, and remains stable under all conditions. Therefore, the facing did not rot or require replacing, saving the contractor unforeseen disruptions.

    

2. Safe working at height with practical products 
   As the walls were 12 meters high, the formwork required support at ground level, as well as at height. To achieve this, the Imperial panels were supported by STB 450 support frames. To simplify adapting the height without disassembling the support frame, 150 centimeter extension units were added on top of the basic 450 centimeter support frame height.For safe support for heights above 6 meters, Triplex heavy-duty braces were used. Their modular flexibility ensured that the required strength to support the formwork could be achieved by combining different assemblies to the desired length. They also provided support for the KLK climbing brackets, which were used both as working platforms and as support platforms for the formwork.

   
   The single-sided walls were poured in two cycles with formwork lifts of approx 7 meters  and 5 meters. At height, the wall formwork rested on KLK support platforms that climbed the walls in 2.5-meter lifts. The rebar was anchored to the rock on the outside of the walls using rock anchors that were cast before the rebar work commenced.

The Outcome

Despite the remote and underground location and large scale of the project, the embedded enclosure was able to be completed successfully.

Featured Products

• Imperial wall formwork
• STB 450 support frames
• KLK climbing brackets 
• Triplex heavy-duty braces

Client:
Adolfson & Peterson Construction

Project:
NOvA Far Detector Plant

Location:
North Minnesota, USA

Owner:
Fermi National Accelerator Laboratory

Engineering & Support:
MEVA Formwork Systems, Inc.