Drilled shafts or piers have been used as deep foundation load bearing elements in structures for over 100 years. They were developed to solve a number of construction problems. First, they can carry high loads using a minimal amount of space and materials. Second, they are a vibration less alternative to driven piles, and third, they help structures withstand lateral loads.
Drilled Shafts are comprised of a hole drilled by an auger attached to some type of rotary motor. The process of creating the drill shaft or peir is accomplished when down force is placed on the auger while it is being turned. The auger is drilled into the ground and displaces the soil onto the auger flights. The auger is then pulled out of the hole and the soil is removed from the flights. This process is repeated until the desired shaft depth is reached.
Drilled shafts can be anywhere from 8 inches to 10 feet in diameter and as deep as 100 feet. Piers can be drilled by almost any type of machinery, from small skid steers to giant excavators. The type of machinery used in determined by the diameter and the depth of the piers. However, access also plays a determining factor.
Depending on the application, different types of structural materials are used in conjunction with drilled shafts. Soldier walls for instance are comprised of I beams concreted into a drilled shaft. Some portion of the I beam stands above the shaft as part of a retaining wall system. Foundation piers, are drilled shafts reinforced with rebar cages and then filled with concrete.
Lassiter Excavating has been serving the cities of Livermore, Pleasanton, San Ramon, Danville, Walnut Creek, Lafayette, Orinda, Fremont, San Jose, Atherton, Palo Alto, Menlo Park, Stockton, Sacramento and the rest of the San Francisco Bay Area Since 1989.