Lackland Air Force Base
Very soft saturated clays beneath three large rectangular dormitory buildings at Lackland Air Force Base had settled up to five inches, causing the buildings to belly in the middle.
The repair plan was to drill micropiles on either side of the existing footing and pour a haunch tying them together and providing a lifting point. Steel shims and grout were placed between the new haunches and existing footing to support the structure. Once the buildings were supported on the new micropile foundations, existing drilled shaft caissons were then cut free from the footings and the buildings were raised to near original elevations using hydraulic jacks.
Micropiles varied from 3.5-4.5” in diameter, and reinforcing bar was 32-38mm all-thread Geo Drill bar. Micropiles varied in depths, up to 46 feet.