What Does Augered Piling In Construction?
What Does Augered Piling In Construction?
Auger cast piles are a type of drilled foundation in which the pile is drilled to its final depth in one continuous process using a continuous flight auger.
This technique is used in construction to create a concrete deep foundation and involves rotating a hollow stem continuous flight auger into the soil to a designed depth, with concrete or grout then being pumped through the hole.
What Is the Purpose Of Auger Cast Piles?
Auger cast piles, also known as Continuous Flight Augers (CFA) piles, are cast-in-place deep foundation system solutions that use a hollow stem auger with continuous flights.
They are installed by rotating the auger into the soil to a designed depth and pumping concrete or grout through the hollow stem to maintain static head pressure.
This process is monitored using sensitive instrumentation and quality assurance is achieved through non-destructive testing methods.
Auger cast piles are vibration-free foundation piles that can be rapidly installed and are highly cost-efficient in comparison to other piling options. They are less expensive than steel piles due to the availability of local grout and varying reinforcing depending on load and design engineer.
Additionally, they can be used close to vibration-sensitive buildings, equipment, and foundations due to their minimum vibration.
The crew required for installation is usually larger than for driven piles as it typically consists of a superintendent, an operator, a laborer, and a pump operator.
The design procedure used for auger cast piles is an Allowable Stress Design (ASD), which is based on engineering principles outlined in existing Federal Highway Administration (FWHA) and American Association of State Highway Officials (AASHTO) publications.
What Are the Advantages of Auger Cast Piles?
Auger cast piles (CFA) have several advantages over driven piles, including a broad range of auger sizes for the economical use of construction materials, low noise emissions, minimal levels of vibration, and higher load capacities on larger diameter piles.
CFA piles are also suitable for tension loads at stability elements and can be installed in very long lengths.
Additionally, CFA piles require less construction traffic than driven piles and do not require casings when driven into the sand below the water table.
However, CFA piles have some disadvantages compared to driven piles, such as a higher waste of concrete as a percentage than traditional bored piles and limitations in length due to lifting forces required to withdraw casing.
What Are the Disadvantages of Auger Cast Piles?
The main disadvantages of auger cast piles are that the cost of construction for low-scale construction may not be economical, soil mining can cause settlement and damage to adjacent structures if the proper auger rotation and penetration rate are not maintained.
Extensive testing and monitoring is required to ensure quality control and structural integrity of piles. Additionally, the torque requirement for auger cast piles generally limits their diameter and length when compared to drilled shafts.
What Is the Maximum Depth of Auger Cast Piles?
The maximum depth of auger cast piles is 165 feet. Morris-Shea’s fleet of powerful drill rigs can install CFA piles in diameters from 14 inches to 5 feet with maximum depths of 165 feet.
Malcolm Drilling states that CFA piles can be installed very efficiently with modern high-torque hydraulic drilling rigs up to a depth of 125 feet and 60 inches in diameter.
What Is The Auger Cast Pile Installation Process?
The auger cast pile installation process involves rotating a hollow stem continuous flight auger into the soil to a designed depth and pumping concrete or grout through the auger.
The piles can range in diameter from 12 to 36 inches and can be installed faster by drilling the hole in one continuous process.
Multiple criteria are used to determine where to stop the tip of the pile, and during installation, it is typical (and required by IBC 1810.3.3) for it to be a messy operation.
