Historic Bolivar County Courthouse
The Problem:
The historic courthouse, erected in 1922, experienced major foundation and structural damages over the life of the structure. Significant settlement caused the north section of the building to pull away from the south end. Settlement was due primarily to heavy concrete vaults within the courthouse constructed over unsuitable soils with improper drainage systems. Cement-based pressure grouting was used in previous years in an attempt to mitigate settlement but was unsuccessful.
The Solution:
To prevent further settlement, 34 CHANCE® Helical Pulldown™ Micropiles were installed to depths of 40–55 ft. The piles were installed with a 12,000 ft-lb hydraulic motor mounted on a mini-excavator. The piles were then mounted with Heavy Duty underpinning brackets to stabilize the structure. After the structure was securely supported, proper drainage was installed and exterior masonry was restored back to its original useable condition and interior damage was fixed.
Technical Description:
Product
- CHANCE® Helical Pulldown™ Micropiles (34 ea.)
- Helix Configuration: 8", 10", 12" Lead Section
- Shaft Material Type – SS175 (1.75 x 1.75" solid square shaft) with a 5" grout column
- Bracket Type: Heavy Duty Bracket & T-Pipe for SS175 shaft
Loads
- 50 Kip working – 100 Kip ultimate per pile