Edison Building at Cascades Park
PROJECT:
During construction and renovation of the Edison Building at Cascades Park, it was discovered that the soil below the existing first floor slab was too loose to support the interior column footings that had been designed to support the proposed second floor addition. A local engineering firm performed testing at these interior footing locations to assess the soil conditions and found loose soil conditions to depths of up to 9-10 feet below the floor slab. The Structural Engineer recommended the use of steel helical pipe piles to underpin the proposed columns, so that the load of each column would be transferred through the pile and into deeper, more competent, load bearing soil layers.
The SOLUTION:
CHANCE® Helical Piles were chosen over alternative pile systems, and removal and replacement of the soil, due to the low mobilization costs of helical pile installation equipment, and the ability to install the piles with small construction equipment that could be brought into the building through a 4'-6" wide doorway. Other factors that lead to the decision to choose helical piles were the fact that they do not generate spoils, so no soil would have to be removed from the building, vibration free installation, and the ability to monitor torque for each pile throughout the installation process, using a CHANCE® Digital Torque Indicator. Therefore, the ultimate loading capacity of each pile would be known immediately following pile installation.
The Work:
The deep foundation system consisted of 16 CHANCE® 2-7/8" Round Shaft Pipe Piles. Lead sections consisted of a 10", 12", 14" helix configuration, installed to depths ranging from 14 feet to 28 feet. Piles were equipped with a 7"x7"x0.5" steel new construction pile cap to allow for connection to the new poured column footings. Working loads per pile ranged from 12 kips to 25 kips in compression. The additional costs associated with the deep foundation were partially offset by the speed at which the piles were able to be installed. The 16 piles were installed in 1, 10 hour work day. This allowed the interior work to continue on without delay.
Galvanized 10,12,14 lead section being advanced. Digital Torque Indicator mounted between the drive head and drive tool.
Doorway through which the installation equipment was brought into the building.
7x7x0.5 new construction pile caps set at elevations 3 inches from bottom of footing.