When should I use Ductile Iron Piles?
- Tight access, limited laydown area or variable grades.
- Vibration-sensitivity.
- Low overhead clearance restrictions (18 feet and above).
- Building additions.
- Deep bearing layers that result in pile splicing or slow pile installation.
If you are considering these techniques for your project:
- Micropiles.
- Helical Piles.
- Short piles where installation vibrations, speed or project site constraints or size makes a good fit.
- Long piles where elimination of splicing or working with small sections maximizes the benefit.
- Poor soil conditions – deep soft soils, fills and/or organics
- Vibration sensitivity
- Adjacent structures
- Difficult access and constrained sites
- Low overhead
- Variable grades
Benefits of Ductile Iron Piles
Cost-Effective
Often provide 15-25% cost savings over drilled micropiles and other deep foundation systems.
Rapid Installation
Daily production rates range from 600 to 1,400 feet per crew.
Low Vibration
High-frequency, low amplitude driving energy results in low vibrations allowing installation to occur within and adjacent to existing structures.
High Load-Carrying Capacity
Working capacities range from 25 to more than 100 tons in compression, and often 20 to 50 tons in tension.
Depth Flexibility
The Plug & Drive System allows for easy length adjustments in the field when faced with fluctuating bearing layer depths. The system can easily be installed to 20 feet or more than 100 feet by simply adding additional DIP sections with the Plug & Drive moment-resisting, drive-on connection.
Easy Access
Mobile track-mounted equipment and modular pile sections allow for rapid work in constrained areas, sloping ground and limited lay-down areas.
Minimal Waste
The system generates virtually no waste since the cut-off section of pile is used as the starter pile for the next location. This is a significant advantage over traditional steel piles (pipe or H-piles) on sites with varying rock elevations that would result in wasted cut-off material or having to add in costly field splicing. Ductile Iron Piles eliminate these concerns completely.
Quality Installation
Load-bearing capacity and pile length are determined on-site through load testing and monitoring of penetration resistance and driving.
Typical Applications
Ductile Iron Piles provide reliable support for commercial, industrial, residential and infrastructure projects including new construction, additions to existing facilities and interior retrofit applications. Ductile Iron Piles provide cost-effective deep foundation solutions for foundation and floor slab support to resist compression, tension and lateral loads. The system offers high value solutions for the following challenges:
Low Overhead
Deep foundation options for interior applications are often limited due to access and overhead obstructions. Ductile Iron Piles are uniquely positioned to provide a rapid, cost-effective solution for interior work in commercial, industrial, warehousing and other applications. Ductile Iron Piles are a modular system with pile sections that are typically between 16 and 18 feet (5.0 to 5.5 meters) in length. The innovative plug and drive (bell – spigot) joint allows rapid connection of piles to achieve sizable depths even with limited overhead clearance. Further, pile sections can be cut in half or thirds and connected with drive-on couplers to allow work in limited overhead conditions. Installers of the Ductile Iron Pile system routinely work within overhead clearances of 18 feet or above. By providing higher capacities than light-duty helical piles and less cost and faster installations than large diameter helical piles and micropiles, Ductile Iron Piles offer a high value deep foundation option when working in low-overhead conditions.
Soft Soils
Deep foundations have long been used to penetrate and bypass soft soils to prevent unacceptable settlement or even bearing capacity failure of supported structures. Ductile Iron Piles are driven rapidly through soft soils to transfer structural loads to underlying stronger soils and, in some cases, can be advanced (pushed) using only the weight and crowd force of the excavator and percussion hammer. Ductile Iron Piles are specifically designed to resist buckling of the pile surrounded by soft layers at design loads typically ranging from 25 to 100 tons. The QC observation during installation allows for the detection of the soft zone to verify the piles develop capacity in competent ground conditions below soft zones of soil. With the modular nature of Ductile Iron Piles, added pile lengths to penetrate deeper-than-anticipated soft zones is easily achieved by adding pile sections using the rapid, moment-resisting Plug and Drive connection. This eliminates the need for splicing or welding additional pile sections that would be required with traditional driven pile methods.
Urban Fill
Development of urban properties is often complicated by the presence of urban fill below grade. Remnants of past structures on the site often result in obstructions buried within the fill, like pieces of concrete, brick, wood, and various other items. Common remedies include removal and replacement of the unsuitable soils, ground improvement, or deep foundations. Removal and replacement often requires extensive support-of-excavation to avoid impacts to adjacent structures and may require expensive handling of contaminated soils. Traditional deep foundations or ground improvement must penetrate the urban fill and may require expensive drilling equipment capable of delivery high-torque drilling for larger diameter elements. In many cases, the cost for pre-drilling to penetrate and create a clear path for foundation elements drives foundation costs to extreme levels. Small diameter Ductile Iron Piles driven with high frequency, percussion energy have a track record for successful installations on fill sites where the piles effectively displace small obstructions and penetrate the urban fill. When pre-drilling is required, pilot hole diameters for Ductile Iron Piles are much smaller than pre-drill diameters required for other foundation elements, resulting in smaller equipment needs, less effort, and less cost. Additionally, when unexpected obstructions are encountered at sites that result in shallow pile refusal, the modular Ductile Iron Pile system results in less waste when the refused pile must be abandoned. New offset pile locations can easily be started with the remaining, above-grade portion of any abandoned Ductile Iron Pile.
Variable Bedrock
In many geologies, the strength and elevation of competent bedrock makes for great uncertainty in the predicted lengths of deep foundation systems. This is particularly challenging for driven pile systems, which are commonly ordered and delivered in pre-determined lengths. Changes in the bedrock elevation can often result in the need for waiting for additional material combined with slow and costly field splicing when rock is deep. Alternatively, significant wasted pile material can result when shallow rock is encountered, and excessive pile lengths are cut-off. These risks are substantially reduced with Ductile Iron Piles – a modular system with pile sections that are typically between 16 and 18 feet (5.0 to 5.5 meters) in length. The innovative plug and drive (bell – spigot) joint allows easy and rapid connection of pile sections to achieve virtually any length and eliminates field splicing to easily solve the issue of longer piles. Further, the modular nature of Ductile Iron Piles significantly reduces risks associated with large amounts of pile waste. When piles reach early refusal or “set,” the remaining section of pile is cut off and used as a starter pile section on the next pile, thereby eliminating the material waste. Unused pile sections can also be easily re-used on future jobs to allow specialty contractors to have confidence in ordering materials. For sites with variable bedrock, Ductile Iron Piles greatly reduce material waste and lead to the efficient use of pile materials.
Low Vibrations
Ductile Iron Piles are ideally suited for urban conditions or interior construction where vibration levels are a concern. Traditional driven piles use large hammers that generate high amplitude and low frequency vibrations that travel long distances, often exceed vibration thresholds and can cause vibration-related damage to nearby structures. Unlike traditional driven pile installation, Ductile Iron Piles are installed with a standard breaker (percussion) hammer. The percussion hammer delivers high frequency, low amplitude vibration levels. The hammer energy levels are considerably less than a traditional driven pile. Typical peak particle velocities often range from only 0.5 to 1.5 inches/second within a few feet of installation and dissipate rapidly at distances of only 10 or 20 feet away from the installation. With these low vibration levels, Ductile Iron Piles are often a preferred approach for projects featuring building additions, urban construction and interior, low-overhead projects.
Adjacent Structures
Construction of building additions often requires foundation systems capable of generating low vibrations during installation and working in close proximity to existing buildings for new foundation work. Ductile Iron Piles are installed using medium-sized excavators (i.e. 20 to 30 tons) that are able to maneuver close to existing buildings on sites with tight access. Driving is performed using a standard breaker (percussion) hammer that generates high frequency, low amplitude energy. The high frequency energy results in limited vibrations to facilitate pile installation adjacent to existing buildings. The combination of the ease of access and low vibrations make Ductile Iron Piles a good solution for new projects adjacent to existing structures.
Constrained Sites
Projects routinely require work on constrained sites including small site footprints in urban settings, at industrial or commercial facilities with obstructed access or sites requiring work at various grades. Ductile Iron Piles are a preferred solution to easily accommodate the various site constraint challenges. With the modular pile sections, transportation in small bundles makes for ease of delivery and stacking on tight sites to limit staging area needs. The modular pile sections incorporate the Plug and Drive connection to install piles to virtually any practical length while only managing sections of less than 20 ft in length, significantly reducing laydown requirements compared with traditional driven piles, drilled shafts or augercast piles. The excavator-percussion hammer combination limits the amount of space for equipment compared with other larger vertical mast rigs and allows easy maneuverability and the ability to install piles from various grades across the site. The low vibration levels during installation reduce the potential for damage during installation. For many reasons, Ductile Iron Piles offer significant benefits on challenging sites.
Organics
Organic soils (peat, organic silt/clay) are often soft and highly compressible and are subject to long-term secondary compression (creep) and material degradation. Depths of organic deposits can be highly variable across a site and are not often discovered until foundation installation. Building sites with organic soils typically require deep foundations to transfer foundation and slab loads below the organic zones. Ductile Iron Piles have been used extensively on sites with organic soils. The Ductile Iron Piles are designed to resist buckling of the pile in the soft layer. The QC observation during installation allows for the detection of the organic zone extent to verify the piles develop capacity in competent ground conditions below the organics. With the modular nature of the piles, added pile length to penetrate deeper-than-anticipated organic zones is easily achieved by adding pile sections using the rapid, moment-resisting Plug and Drive connection.
Frequently Asked Questions
What are Ductile Iron Piles (DIPs)?
Ductile Iron Piles (DIPs) are modular, low vibration driven piles manufactured from ductile iron via a centrifugal-casting process. With standard DIP lengths of 16.4 feet (5 m), the piles employ a unique Plug & Drive connection system enabling additional pile lengths to be quickly added without added mechanical connections or field splicing. Piles of varying lengths can be driven to depth and the cut-off section is used as the lead section for the next pile, resulting in minimal or no waste.
