what are helical piers

What Are Helical Piles?

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Description

WHAT ARE HELICAL PIERS & HELICAL PILES

Helical piers, also known as anchors, piles or screwpiles, are deep foundation solutions used to secure new or repair existing foundations. Due to their design and ease to install, they are most commonly used whenever soil conditions prevent standard foundation solutions. Instead of requiring large excavation work, they thread into the ground. This minimizes installation time, requires little soil disturbance, and most importantly transfers the weight of the structure to load bearing soil.

What are helical piles

WHEN SHOULD THEY BE USED?

Helical Piers and Piles are needed for numerous residential and commercial applications and may be used when the job specifies caissons, driven piles or mini piles. Once foundations are exposed to moisture over a long period of time or construction is cited on unstable soil, structural and foundation damage becomes visible. To repair the foundations of your property and ensure the building does not lose value, they are used to stabilize the foundation. Helical piers and piles can also be used to repair foundations when foundation failure becomes apparent:

  • Windows and doors are sticking, hard to open
  • There are large gaps in window and door frames
  • Interior plaster walls are cracking
  • Multiple nail pops are appearing in ceilings and walls
  • Walls are beginning to lean noticeably
  • Floors are starting to settle and become uneven
  • Chimneys are tilting or leaning
  • Cracks can be seen in foundations or basement walls
what are helical piles

Hercules Installation 2020

Technical Drawings

Central Shaft Steel

i. Round Hollow Shaft

Mechanical Properties

  • Minimum Yield Strength: 55ksi
  • Minimum Tensile Strength: 75ksi

Shaft Size

  • 2-7/8”o.d. (.217” w.t)
  • 3-1/2”o.d. (.254” w.t)

Torque Rating

  • 2-7/8”o.d. (.217” w.t) – 8,000ft-lbs
  • 3-1/2”o.d. (.254” w.t) – 11,000ft-lbs.

Torque to Capacity Ratio

  • 2-7/8”o.d. (.217” w.t) – 9 ft-1(recommended)
  • 3-1/2”o.d. (.254” w.t) – 7 ft-1(recommended)

Ultimate Mechanical Capacity

  • 2-7/8”o.d. (.217” w.t) – 80,000lbs
  • 3-1/2”o.d. (.254” w.t) – 120,000lbs

ii. Solid Square Shaft

Mechanical Properties

  • Minimum Yield Strength: 90ksi
  • Minimum Tensile Strength: 120ksi

Shaft Size

  • 1-1/2” x 1-1/2”
  • 1-3/4” x 1-3/4”

Torque Rating

  • 1-1/2” x 1-1/2” – 7,000ft-lbs.
  • 1-3/4” x 1-3/4”– 10,000ft-lbs.

Torque to Capacity Ratio

  • 1-1/2” x 1-1/2”– 10 ft-1(recommended)
  • 1-3/4” x 1-3/4”– – 10 ft-1(recommended)

Ultimate Mechanical Capacity

  • 1-1/2” x 1-1/2”– 80,000lbs.
  • 1-3/4” x 1-3/4”– 100,000lbs.

Helices

  1. Minimum Yield Strength: 50ksi
  2. Diameter: 8 inch – 16 inch
  3. Pitch: 3inch or 6inch
  4. Thickness: 3/8inch or 1/2inch

Finish

  1. Galvanized or bare steel
  2. All galvanized steel per ASTM A123/153

Hardware

  1. Grade 5 or equivalent for 2 -7/8” or 3 -1/2” piles, and ¾” x 4 -1/2” and ¾” x 5 -1/2” Respectively.
  2. Grade 8 or equivalent for 1-1/2” or 1 -3/4” pile, and ¾” x 3 -1/2” and 7/8” x 4 -1/2” Respectively.

Bracket

  1. All steel plate 36 ksi min. Yield.
Sample Footing Design
what are helical piles-TIEBACK-Sample-Tie-Back-Design
Sample Tie Back Design

Applications

Residential Applications

Homeowners choose them to prevent sagging foundations. If you are experiencing cracked foundations or drywall it may be signs that your foundation needs a permanent stability solution.

Commercial Applications

Contractors use our piering systems whenever the soil sample indicates a deep foundation solution. This is required when they want to avoid excavation expenses, such as tilt-up construction.

Industrial Applications

Plant managers love our anchors because of speed in which they are installed. With our system there is minimum impact to daily operations.

The Two Types of Helical Piers

PierTech manufactures two patented types of piers. Round shaft, best used in compression situations, and square shaft best used in tension situations.

The Best in the Industry

  • Made from the highest quality steel
  • Higher torque capacity than the competition
  • Superior lateral strength and stability
  • Galvanized or bare steel options
  • Square or round shafts

Round Shaft Helical Piles

In applications where compression is the primary consideration, we recommend using round shaft piers. In Compression our round shaft has several advantages over the typical square shaft.

Round Shaft Advantages

  • Superior lateral stability
  • Greater section modulus strength to resist twisting and deflection
  • Patented cross-bolt connection
  • Greater load capacities
  • Easy to install
  • Installs in any season
  • Minimal soil disturbance
  • Not affected by a high water table

Composition:

  • A round hollow shaft 2 7/8″ thru 12 ¾” O.D. typical.
  • Circular tapered plates (helices) are welded to the center of the shaft.
  • Helix diameters can range between 6″ – 48″ with a thickness of 3/8″ – 1″.
  • Helix pitch will range from 3″ – 6″.
  • Galvanized or bare steel options available

Square Shaft Helical Piles

In applications where tension is the primary consideration, we recommend the Square Shaft Piers. They have several advantages over the typical square shaft anchors.

Square Shaft Advantages:

  • Greater yield and Tensile strength
  • Patented Cross-bolt Connection
  • Increased safety factor
  • Higher torque capacity
  • Easy to install
  • Installs in any season
  • Minimal soil disturbance
  • Not affected by a high water table

Composition:

  • A square solid shaft 1 ¼” thru 2″ O.D. typical.
  • Circular tapered plates (helices) are welded to the center of the shaft.
  • Helix diameters can range between 6″ – 48″ with a thickness of 3/8″ – 1″.
  • Helix pitch will range from 3″ – 6″
  • Galvanized or bare steel options available

Cross Lock Connection

Our Patented Cross Lock Connection was awarded ESR-3969 from ICC-ES for our 2.875″ diameter helical pile system.  The connection instantly aligns and locks in place,  eliminating the issue of lining up bolt holes or wasting time threading a bolt through a deformed hole. The Cross-Lock allows installers to simply connect and quickly continue the installation process.

Cross Lock Advantages

  • Instant alignment
  • Complete steel on steel connection
  • Torque is fully contained in the coupling
  • Zero bolt hole elongation during installation
  • ICC-ER (ESR-3969) Certified
  • Superior strength and lateral stability
  • Reduce installation times up to 50%

How Do They Work?

The helical screw pile is screwed into the soil until a desirable load capacity has been achieved. It is then spaced at pre-calculated intervals to spread the load of the structure. In foundation repair applications, brackets are then attached to the foundation wall bases and weight is transferred to the pile.