Owner: Architect of the Capital Client: Clark Construction Scope: 114 Auger Cast (ACIP) Piles Location: DC, on the Mall Capacity: 60 Kips
Background: This project required the installation of new Auger Cast Piles for the support of additional structures and interior renovations.
The Problem: Access; the new construction piling had to be placed in an excavation running the full length of the project and approximately 20 feet in depth. Due to the interior struts required for the excavation support, the piling rig could not enter the excavation. This required a unique set up in order to meet the space constraints outside the excavation. In addition several piling were required inside the existing structure to support new equipment required for the facility. CCGI was asked to evaluate the use of limited headroom equipment to access the interior spaces of the building to install the required piles.
Solution: CCGI first evaluated the piles that were required in the excavation. We devised an installation procedure that required the crane to sit in the one lane of traffic that we were afforded next to the excavation and had the excavation support designed for the crane’s loading characteristics. This allowed the crane to reach over the excavation and drop the swinging leads between the excavation supports to reach all of the required pile locations. This method required the operator to work in the blind with redundant communication systems in place with the ground crew. The access solution for the interior piles relied again on the crane and lead system. As the roof of the building was off when the piles were to be installed, we simply lifted the drilling operation over the exterior walls and into the rooms where piling were needed.
The System: Auger Cast (ACIP) Piles utilize a continuous flight auger to advance the pile to the required tip elevation. Grout is then pumped through the hollow stem of the auger. Once the grouting operation is complete the required steel reinforcement section is lowered into the fluid grout and the pile is left to cure. This system proves very economical for capacities ranging from 20 to 150 tons in design. The system is also flexible when it comes to the different types of equipment that can install the system in different access conditions.
Owner: Architect of the Capital