Helical Technology Overview

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Cost

  • Time is money! Helical Piles take much less time to install than other deep foundation technologies.
  • They can be installed in most weather conditions and through all four seasons of the year. This saves money and cost from delays that weather conditions can cause.
  • They can be loaded immediately after installation. There is no cure time so rebar and concrete can be started immediately behind the anchor install (Compared to Caisson which needs to meet a minimum compressive strength before you can continue with construction).
  • Installation produces no spoils to remove or remediate, saving time and money.
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Speed

  • Helical Piles are can be installed much faster that Caisson and other deep foundation technologies. Fast installation saves time and money.
    • No curing time
    • No weather delays
    • Easy to work with
    • More flexible and easy to correct or change
  • At a rate of 15 RPM's and an advancement of 3" per revolution, a typical 30' section can be installed in about 10 minutes with no spoils, concrete or rebar needed
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Size

  • Helical Piles use a much smaller working footprint than Caisson or Auger piles.
  • They can be installed in limited access areas like existing buildings or sensitive environments. You can get your skid steer loader through a small entrance where the rig can't get access.
    • Helical Piles typically only require a skid steer loader to install compared to the big rigs used in Caisson construction.
  • Limited storage needed on site
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No Spoils

  • Installation produces no spoils to remove or remediate. Consider what is involved and impacted when spoils are an issue:
    • Spoils increase the footprint of the work area because it needs to be stockpiled somewhere
    • It needs to be loaded on trucks and hauled away which uses time, manpower and cost
    • There is potential exposure to hazardous soil that is deep in the ground
    • This is often times a gray area in the contract as to who's responsible for remediation.
    • In fact many times the estimator will overlook this when submitting pricing
  • No spoils give you more working footprint and more time.
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Vibration and Noise

  • Helical Piles produce little to no vibration during installation. This decreases possible damage to existing structures from soil movement
  • Vibration could damage things like older buildings, cracks in existing masonry, Windows, and is disturbing to anyone working or living nearby.
  • There isn't any pounding or drive pile noise that can be very annoying to anyone nearby.
  • Noise is limited to the small equipment needed to install the piles. Caisson typically requires large trucks and rigs to install.
  • Vibration and noise impacts other business and neighbors which can cause problems, create delays and make for a hostile environment.
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Safety

  • There is no need for excavation. Specifically open-hole excavation.
  • Open and deep holes present a number of safety issues that require special equipment, time and procedures and special training.
  • There aren't any large rigs used, so damage or accidents caused by hanging electrical wires is not an issue.
  • Less equipment, materials and time on the job equates to a safer environment with less exposure and risk.
  • Eliminates down-hole work and inspection.
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Quality and Design

  • Seamless tube shafts with high tensile strength = higher torsion strength than the competition.
    • This allows installation into stronger soil strata for higher load capacity.
  • High yielding flights for higher compression loads
  • All connections are precision "CNC" machined to .001"
  • Patented Inertia Welding used on all connections allowing a streamlined one piece design.
  • Quality galvanizing (hot-dipped process) for enhanced underground corrosion resistance.
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Strength and Efficiency

  • Most helical pile failures in the field occur at the joint. This eliminates joint weakness. Under higher torque bolts and joints elongate and get distorted making them weaker.
    • The typical industry standard helical section has holes drilled into the ends of the tube section only relying on the steel tube for strength.
    • Since both the box and pin connections on Helical Anchors are precision machined, we can hold tolerances to .001 of an inch. This gives the connection a very precise fit adding lateral support. This connection also allows us to shoulder or transfer the load on the anchor walls vs. the standard method of relying on the bolted connection.
  • Helical Anchors have the highest torque ratings in the industry!
    • We can use smaller diameter piles (shafts) for the same load capacity.
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Patented Inertia Welding

  • 80 KSI pipe is inertia welded to provide a streamlined one-piece anchor design
  • The competition typically uses "Upset Pipe" which thins out the steel and makes it less stable and makes it trickier to install in the field.
  • This helps to prevent joint failures which are the most common cause of pile failure.
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Torque Indicator

  • With this you know the capacity for every anchor - you don't necessarily know with 100% certainty the load capacity of other technologies.
  • This lets you know the load capacity immediately for each individual anchor so that you can verify and test prior to putting in more piles.
  • Caisson and auger piles require a test installation unit which takes time and money to install and you still don't know if it is acceptable.
  • With other technologies you may not know or be able to verify until a majority of the work is done because there is no real-time capacity information allowing you to accommodate or remedy if a problem is encountered.
  • Allows for real-time verification of torque that can be acted upon immediately.
  • The recorded data can be downloaded to a laptop and output to spreadsheets for easier analysis and distribution.
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Building Foundations

  • Warehouses
  • Parking Garages
  • Commercial Buildings
  • Modular Homes/Multi-Family Housing
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Towers

  • Cell Towers
  • Wind and Energy Towers
  • Guyed Wires
  • Highway Lighting
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Solar Power Farms

Solar arrays are generally placed on inexpensive or undesirable land. Often times this land contains substandard soils. Helical Piles are perfect for this kind of application.
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Wetland Walkways

Helical Piles reduce the environmental impact in marshes and wetlands making them appealing for boardwalk support.
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Retaining Walls and Tie Backs

Helical Piles can be installed temporarily for braced excavations or for permanent retaining walls.
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Green Structures

Using helical piles with 'Green" projects will significantly reduce the footprint left on the site.
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Pipelines

Through wetlands and unstable soil, helical piles can support pipelines to prevent buoyancy or compressive issues using a "saddle" system.
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Central Steel Shaft

  • Helical Anchor's pipe is fabricated from seamless Grade 80 steel tubing using all domestic, oil grade steel.
  • This is a big reason why Helical Anchors, Inc. have the highest torque ratings in the industry!
  • The industry standard is either to use a seamed ERW material, Schedule 40 grade or even used oilfield pipe and only yield 50 KSI.
  • We can use smaller diameter piles (shafts) for the same load capacity.
  • We provide a wide variety of shaft sizes to accommodate any application. The central shaft can be fabricated in lengths from 36" to 120".
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Helical Plates

  • All plates are fabricated with Grade 50 steel while most everyone else uses A-36 grade for the helix plate material.
  • Plate sizes vary from 6" to 16" in diameter and have a thickness of 3/8" or 1/2" depending on job requirements.
  • The # and sizes of helical plates may be varied to match soil conditions to the required anchor capacity.
  • The normal pitch of each helix is 3 inches and to ensure that each of them develops full capacity, each succeeding plate is located above the preceding plate a distance equal to 3 times the diameter of the preceding plate.
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Couplings

  • Inertia Welded to the shaft ends to allow attachment of extensions for deeper penetration into ground when needed.
  • On both the box end and pin end of every extension we use 4140 & 4125 hardened alloy that we inertia weld to the tube body. We then quench and temper the connection, normalize and then heat treat to get back to full strength.
    • The industry standard has always been to simply drill holes in the ends of a lesser grade tube, considerably limiting it’s torque capacity.
  • All connections are precision machined allowing the loads to be shouldered from tube to tube, while the industry standard is to rely on the bolt connection for it’s strength.
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Connectors / Brackets

  • The top of the anchor connects to the foundation or structure with different types of connectors depending on the application.
  • This allows the loads from the foundation to be transferred to the helical anchors and then to the soil at a deeper level.
  • Ultimately this will give you more bearing surface for load and support.
  • Underpinning Bracket is used for stabilizing/lifting repairs of existing foundations. Anchor bolts hold the bracket to the footing. The load is then transferred to the anchor.
  • New Cap Construction is placed on foundation anchors for support of new structures.
  • Heavy and Light Duty Brackets are used for commercial buildings and industrial rated loads of different sizes.
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Wireless Torque Indicator

The wireless torque indicator allows real time torque to be viewed and recorded during the installation process of every anchor - you don't necessarily know with 100% certainty the load capacity of other technologies.
  • Allows for real-time verification of capacity that can be acted upon immediately.
  • The live time torque that is saved, can be printed out. The information includes individual pile numbers and the torque value for each.
  • The recorded data can be downloaded to a laptop and output to spreadsheets for easier analysis.
  • There is no guessing or estimating of critical data. It is real and verified information that allows you to document and feel confident that everything is within specifications.
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Anchor Specifications

Click here to see full report
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Helical Anchor Accessories

Click here to view this PDF

Design Considerations

  • Theoretical Capacity
  • Capacity - Torque Correlations
  • Buckling
  • Lateral Resistance
  • Corrosion
  • Group Efficiency
  • Specifications
  • Site Access
  • Contaminated Soils
  • Economics

For additional design information click here.
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Torque VS Capacity

  • The relationship between torque applied during anchor installation and the installed anchor's load capacity
  • The torque versus anchor capacity method was used to verify the load capacity at installation.
  • This method multiplies the effective torsional resistance encountered during installation of the helical anchor by an empirical factor to determine the compression load limit or pullout resistance of the anchor
  • Empirical Torque Factor is related to friction during installation and is impacted by shaft size and shape, soil properties, and number and size of helix plates.

Predicting Capacity

  • Capacity is the maximum load a foundation/soil system can support
  • Bearing capacity varies depending on the following factors
    • Soil properties
    • Soil conditions
    • Anchor design characteristics
    • Installation parameters
    • Load Type:Tension - Compression - Shear
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Calculating Capacity

  • Individual Bearing method
    • This method assumes a bearing failure of the soil supporting each helix
    • Bearing capacity varies as a function of the soils angle of internal friction and the soil density description
    • Capacity is determined by calculating the ultimate bearing resistance of the soil at each helix and multiplying it times the projected area of the helix. The total capacity of a multi-helix system is then the sum of the individual capacities.
  • Torque correlation method
    • This method makes use of the empirically-derived relationship between installed capacity and the torsion resistance encountered during installation.
    • The empirical torque is related to friction during installation. It is not a unique number and it varies from 3 to 20 depending on the shaft size and shape, soil properties and numbers of helix plates and their sizes.
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Soil Cohesion

  • Commonly, soil is not homogeneous through the entire required depth of installation; a soil behavior analysis must be done in order to be able to calculate the theoretical ultimate capacity and varies quite a lot depending on the site conditions.
  • Cohesion is the term used for shear strength that exists in the absence of compressive stress.
  • Non-Cohesive Soil (sand and gravel) shear strength exists only in the presence of compressive stress
  • Cohesive Soil (clay) is composed of particles that adhere to each other even in the absence of compressive stress
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Projected Helical Plate Areas

  • The projected area of an individual helix is the area of the helix plate less the cross sectional area of the shaft.
  • The sum of the projected total area is required to determine the capacity of a helical anchor.
  • Helical Anchors, Inc. usually recommends an angle of approximately 60 degrees and no more than 90 degrees angle.
  • Helical plates may be cut to a maximum of 90 degrees angle to improve penetration in rocky soils.
  • The angle of the cut can reduce the projected area by approximately 20 to 25% and must be taken into consideration when designing.