They generate no vibrations and can be installed with only 6 feet of overhead space and in other limited-access situations. . In soft soils, they transfer a structural load further down to stronger and less compressible materials. Square shaft products are generally used in small to moderate loading applications, and they provide excellent tension resistance. Depending on the number of piles inspected and observed, the factor of safety can vary between 1.5 and 2.5 (Perko 2009). The required depth of penetration of a helical pier into stable soils below expansive soils is still debated. Helical piles are growing in popularity in an exponential manner due to the many advantages they offer. Each pier is load tested and precisely configured for your exact soil requirements. Helical Piles: An Emerging Two Century Old Deep Foundation Solution. A benefit to helical piles is increased predictability of performance due to an empirical relationship between installation torque and soil capacity. Therefore, helical piles are quite customizable and the experience of a design engineer with the technology will really play a factor in getting the most efficient pile possible to site that will satisfy the final design and the forces which will be encountered during installation. The capacity of a helical pile must equal or exceed the factored . Fig 8: Example installation setup (Perko 2009). They are a great alternative to the traditional concrete caissons for new construction applications in commercial projects. After several decades of declining usage, helical piles once again emerged as a viable option as hydraulics and planetary gears and high torque drives came to market. Consider helical piers to support auxiliary structures and slabs such as outbuildings, sheds, patios, mezzanines, balconies, garages, pole barns or parking covers. Specializing in the design and manufacturing of pipeline anchors and high-capacity helical piles since 1981, Cyntech has grown to become the industry leader in North America and the world. The helical piles are screwed into the stable soil until the prescribed depth is reached. Figure 4 provides an example of a manufacturer-provided chart for determining the proper blade diameter given the needed capacity and SPT blow count (Perko 2009). Helical piers are versatile in that they can resist both upward and downward forces, which is ideal for Colorados expansive soil and the structural problems presented by it. Underpinning Recognizing that helical piles were performing well in such a challenging environment, the engineering community in the late 1800s began to leverage helical piles mainland. Commercial helical pier installation can be performed quickly providing a firm foundation for the lifetime of the building. When soil is soft or oversaturated, it will settle and pack down over time. The weight of your home is transferred to the new foundation support system and adjusted using hydraulic equipment. Main (Denver): 720-202-7015 By measuring turning resistance as a pier is driven, EagleLIFT contractors can determine when the pier has reached competent load-bearing soil. Raising the Foundation No excavation and low footprint In addition, piles must be placed far enough apart to avoid group action. While there may be some minor differences in particular naming conventions, these names are often used interchangeably. Helical piles can be unsuitable if early refusal occurs in conditions with expansive soils (Perko 2009). The slender shaft of a helical pile does not experience the same negative down-drag in expansive soils simply because the shaft is smaller in comparison. Essentials for both Commercial and Residential Foundation Repair & New Construction. You are currently using Internet Explorer 7/8/9, which is not supported by our site. Theyre equally suited for both new construction and foundation repair applications, and theyre the engineers choice for commercial, industrial and residential buildings of virtually every type. Model tests are performed with . Some soil can require pre-drilling, however, and that can take several days. When comparing the contribution of the shaft and the bearing plates to the axial compressive resistance in clays, the shaft of the helical pile tends to contribute more to load with increasingly stiff clays. Fast forward to 2021, helical piles have grown exponentially over the past decade across various markets. Journal of the Institution of Civil Engineers, 34(5), 473. where is a fitting constant of 4.33 inches, and N70 is SPT blow count with an energy ratio of 70. x is a fitting constant, equal to 0.37 for piles with shaft diameters between 2.875 inches to 3.5 inches. The shafts are advanced to bearing depth by twisting them into the soil while monitoring torque to estimate the pile capacity. Helical piles can be put to use in many structures, ranging from buildings to piers to retaining walls. The factor of safety used for helical piles is typically around 2.0 as opposed to 3.0 for other foundation systems. Specialized manufacturers (such as Olshans partner, Earth Contact Products) have improved helical pier technology over the years, dramatically boosting reliability while cutting costs and simplifying installation. If you want moreinformation on structural engineering basics, feel free tograb our Ultimate Guide here or check out our Structural Engineering Basics Online Program! Helical piles are growing at an exponential pace as is the confidence in helical piles within the general engineering community. 1 0 obj
Please enter your email address. The success of the Helical screw anchor system is based on decades of similar use of Chance anchors by electrical utilities. %
The rigid three-bolt coupling which connects helical lead sections and extensions makes the pile resistant to bending, unlike the pin and bolt coupling found in square-shaft helical pile solutions. For the best experience, please use one of the latest browsers. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 12 0 R] /MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
Estimation of uplift capacity of helical anchors in clays. Sheet piles are used to restrain soft soil above the bedrock in this excavation. The behaviour of model screw piles in cohesive soils. A site where piles are being load tested can result in leaner design based on the actual performance of the piles. Here are just some of the settings where helical piers are ideal: Install during site preparation to ensure that all foundation components are fully supported, no matter what your local soil conditions might be. The process is considered quick and can be completed within a matter of hours with minimal cleanup. VersaPile, Inc. Helical Pile Contractors. Further analysis with transparent soils and laser-aided particle image velocimetry has also found that plate spacing ratios less than 1.5 result in a stiffer response and thus less settlement in clays (Stainer and Hird 2014). "addressLocality": "Greenwood Village", Helical (screw) pilesare designed to carry axial and/or lateral and/or moment loads. "@type": "HomeAndConstructionBusiness", Skip to content. Delta There are varying models of differing complexity that calculate Kt from various pile parameters, like plate diameter, plate thickness, shaft diameter, etc (Perko 2009). Helical piles can also be installed in a tie-back system, where one pile is installed at an angle to provide lateral resistance while another is installed vertically to provide vertical resistance (Perko 2009). Livneh, B., & El Naggar, M. H. (2008). Helical piles are deep foundation elements constructed using steel shafts with helical flights. With over 100 years of structural engineering experience, the Chance Helical Underpinning System is unmatched. Thats an oversimplified way to illustrate how helical piers work. As a premier contractor in California, Nevada, and Arizona, EagleLIFT uses helical piles with polymer injection to provide substantial anchoring for building foundations. } Square shaft piles are able to penetrate dense and cobble-rich soil when compared to their helical pipe pile equivalents, but they have lower resistance to buckling and negligible lateral load resistance. endobj
Helical piles are deep foundation elements that are used to support new foundations or underpin existing foundations. {R.G-)-|[ w zc=e-6*qQ{ Hoboken, NJ: John Wiley & Sons. To learn more about helical pierand pile installation and to see if its right for your home or commercial building, call Pinnacle today at (720) 202-7015 (Denver) or (719) 650-9573 (Southern Colorado). Advances in hydraulic construction equipment from the 1960s to the present have made installation easier, faster and less disruptive to occupied properties. Our Homeowner Maintenance Checklist will serve as your plan for regular maintenance particularly as it relates to foundation issues, concrete settlement, and structural repair. They tend to be the most cost effective and practical option while maintaining minimal environmental impact. "url": "https://pinnaclestructuralservices.com/", In the late 1800s and early 1900s hundreds of lighthouses were constructed along the eastern seaboard of North America on helical piles remarkably, some of them still stand today. Light capacity helical piles are installed with portable hydraulic torsion bars or towers, mini-skid steers, skid steers, mini excavators, midi excavators, and utility sector style auger trucks (Digger Derricks). At EagleLIFT, our rigid three-bolt coupling connects helical lead sections and extensions making the pile resistant to bending. The depth of the central support and the diameter and spacing of the bearing plates is determined by the local soil type and by the specs of the foundation you need to support. Helical piles were well known for their ability to support compressive and tensile loads but, as mentioned above, they were laboursome to install. Engineers have commonly recommended helical piers for decades to both repair and stabilize foundations for all types of commercial and residential structures. At that time, installation was usually powered by hand or by oxen. (Piles with a diameter over 6 5/8 do not contain polyurethane.) Helical piers can also be customized for any site requirements. Ground Improvement, Deep Foundations The amount of load that a pile can resist. This is due to the fact that helical pile capacity can be verified with installation torque using the capacity-torque ratio described previously. This is because the homes weight is not providing the compressive strength on the soils as it was before the piers. Something that can help is being aware of the signs of foundation settlementand Typically, a pile with bearing plates has 1.2 to 1.5 times the capacity of a pile with just a shaft (Prasad and Rao 1996). Chance Anchors About Us 4 Benefits that the cloud is bringing to Structural Engineering, 5 Benefits of Revit for Structural Engineers. Lateralcapacity of helical piles in clays. ", Helical screws are also available. The solution was so successful that he patented the idea with his sons, leading to installations all over the world in the mid to late 19th century. An additional step we might also see on higher liability project sites is the presence of a third party engineer to supervise the installation. Reputable civil and structural engineers now routinely specify helical piers to provide deep support for both new and existing foundations in all kinds of residential, commercial, and industrial structures. Not only do the helical plates advance the pier deep into the soil during installation, but they also help to anchor the pier solidly into place. You would not be able to drive a micropile into bedrock no. EagleLIFT providers quality commercial helical pier installation services. 8547 E Arapahoe Rd Suite J170 All components are hot-dip galvanized to increase product life in aggressive soils. Download, print, or save one of our many product and installation brochures so you can learn more about our company, our available products and services, and the steps taken to heal your home. All system components are hot-dip galvanized to increase product life in aggressive soils, and are made in the United States. In short, helical piles are a very versatile deep foundation and this versatility results in a long list of benefits, including but not limited to: There are no silver bullets in the world of deep foundations and helical piles are no exception. The load from the foundation is passed from a connection point to the shaft, from the shaft to the discs, and from the discs to the surrounding soil. Helical piles are an end-bearing deep foundation system that has applications in both compression and tension. Post-installation techniques can also be employed if the connections and shafts need to be stiffened, although it is ideal to make those connections as stiff as possible during the initial installation process so there is no risk of buckling. Helical piles, also known as screw piles, screw anchors, helical piers, and helical anchors are highly adaptable foundation lifting and stabilization systems. By applying torque to the shaft this action installs the helical pile with minimal displacement or disturbance. Surrey To design a pile, the engineer reviews three factors: The loads that the structure will apply to the pile it connects to. Rancho Cucamonga, CA 91730, 110 2nd Ave. South Unit A-14 Helical piles can be further stabilized with the addition of a polymer injection. As hinted in its name, helical piles differ from other deep foundations and are most notable for having spiraling blades along their shafts, as opposed to having a relatively uniform shape like driven piles and micropiles. "addressCountry": "United States" Slowly, helical piles emerged back into the deep foundation market. Imagine trying to lift a heavy piece of furniture by yourself. They did a great job and everything looks fantastic. Helical pile capacity in clays is optimized when the bearing plates are spaced 1.0 to 1.5 plate diameters apart along the shaft (Prasad and Rao 1996). The top of the pile is the incorporated into the foundation system via a bracket or other connection method. To install the helical pile, a torque motor that can meet the required design torque is all that is really needed. Can usually be installed by two people using conventional equipment. Helical piles are also versatile in the sense that they can be removed for temporary use. Helical piles are not often included as regular curriculum for structural or geotechnical engineers and therefore expertise in helical piles is considered niche; Universal guidelines are available but not always utilized which results in manufacturers relying on proprietary data which often lacks testing in a wide range of soils conditions (this is avoided when insisting on universally accepted engineering principles for helical piles); The existence of other variations of screw piles, such as augered or duckbill piles, ground anchors and ground screws add confusion to the market, these piles lack standard design and universal engineering principles do not exist or apply to these similar but very different types of screw piles; Helical piles are not a viable option when there is shallow refusal (impenetrable very dense strata) at or before 1.5 meters from grade; The predictability of torque and capacity when installing in boulders is lowered, load testing would be required in this situation; Performance may be greatly influenced by the ethics of the helical pile contractor, their experience, technical knowledge/engineering pedigree and equipment utilized; Helical piles have smaller shafts compared to other pile options resulting in lower resistance to lateral and/or bending forces (this can be overcome with various strategies including pile caps, larger shafts near surface, grillages or battered resistance piles); When pile must be installed through very dense layers to achieve desired install depths, helical piles may need to be constructed more robustly to resist the installation torques or predrilling may be required; Require quality mill grade steel and certified welds; and.