Drilled Piers

For structures with high column loads, a drilled pier foundation is often an efficient and economical deep foundation choice. We have installed this foundation type with diameters ranging from 2 feet to 10 feet and depths ranging from less than 10 feet to in excess of 100 feet.

Cased Hole Method

A traditional method of constructing drilled piers consists of using temporary steel casing inserted into the drill hole. The casing is telescoped in decreasing diameters until a suitable bearing surface is reached. This method offers an opportunity for bearing surface inspection by a third party.

Slurry Hole Method

Slurry, or wet, construction techniques have gained traction in recent years as a faster, safer, more efficient and more economical alternative to drilled pier construction. In this method, slurry (either polymer or bentonite) is pumped into the excavated hole as it is drilled. These holes are typically machine cleaned and the concrete is placed with a tremie pipe. The concrete displaces the slurry which is pumped out of the hole and either reused or discarded.

Osterberg Load Cell Testing

The slurry hole method of drilled pier construction precludes the opportunity for bearing surface inspection. Therefore, some other form of subsurface load-transfer characterization is often required. One way of evaluating the subsurface is with Osterberg Load Cell Testing (O-cell Testing). The O-cell test consists of a bi-directional expandable load cell that is placed near the bottom of a test shaft. Concrete is placed in the shaft and allowed to cure. Once the concrete is cured, a load test is run by inflating the cell at the bottom of the shaft. Since the cell expands upward and downward, the test allows for independent assessment of both the end bearing and skin friction capacity of the shaft. Once the load transfer is defined, the production shafts can be designed or re-designed, often with improvement upon original assumptions of geotechnical shaft capacity. ABE has performed multiple such tests throughout the Atlanta area and southeast and continues to offer this value engineering service on all drilled pier projects.