Often referred to by many different names, drilled piers, drilled piles, caissons, and CIDH piles, they are all the same type of foundation element. Drilled shaft foundations typically consist of a shaft that is drilled out, includes a pile reinforcing cage, and backfilled with concrete. Drilled Shafts offer a very high capacity foundation solution that can be installed in almost all soil types. Sizes range from 12" up to 144" in diameter with depths ranging from 10' to 150' deep. Construction of drilled shafts can either be performed in the "dry" (no groundwater present) or in the "wet" condition (drilled under fluids.) When drilled shafts are installed in the "wet" the construction techniques and methods used to install a pile can vary. Depending on the soil conditions and ground water elevations Case Pacific employs one of the following methods to install: Polymer Drilling fluids, Bentonite Drilling fluids, or steel casings. The method chosen to install the shafts is determined by the size and depth of pile as well as the soil conditions.
Micropiles are a foundation element consisting of high strength bar and steel casings. Micropiles typically range in size from 6-12" and are installed in either a vertical fashion or slightly battered from vertical.
Micropile construction starts with the installation of a permanent casing that remains in place. The size (both diameter and wall thickness) and length of this casing is determined based on the structural demands on the system as well as the overall length of the micropile. Depending on tensile or compressive load, the diameter and length of the bond zone can be determined. Once this casing is installed the micropile is installed to the designed tip elevation.
Micropiles offer an alternative to drilled pile foundations where access may be tight with low overhead and conventional drilling equipment cannot work. They can also be installed in difficult soil conditions where multiple micropiles can replace a drilled shaft as a more economical solution.