Why Drilled Shafts?
Large diameter drilled shafts are the highest capacity deep foundation typically utilized in the mid south area. Chris-Hill can accommodate shafts from as small as 18 inches to 10 feet in diameter.
Drilled shafts are typically required to support heavy concentrated loads or loads that require an abundance of force to prevent overturning (i.e. cell tower monopoles). The equipment used to drill shafts can also be used to excavate large diameter vertical holes for retaining walls, pile installation, open caissons, and tunnel access shafts.
How it's done
A drill rig, typically on a crawler or truck tire base, advances a drill bit into the ground. In rock, the bit may be backed up by a pneumatic or "down-the-hole" hammer to introduce percussion. Telescopic "kelly bars" extend downward, advancing and retracting the bit to remove soil one "bite" at a time. The shaft remains open during excavation until the earth cannot support itself. At that point, steel casings or heavy liquid slurry must be used to maintain a cylindrical excavation until the drilling depth is achieved. Once excavated, concrete and reinforcing steel is installed in the hole, or the open hole is used for another designed application.
Drilled piers offer the largest load capacity and resistance to overturning of any local deep foundation other than large diameter marine caisson piles. As for the local region, drilled shaft foundations are a very economical choice for many design applications.
Chris-Hill hired Eric Creasy, formerly of McKinney Drilling and Keller, in 2020 to run the drilled shaft arm of Chris-Hill. He has over 20 years of drilling experience.