Helical Pulldown™ Micropiles
Load capacities higher than ever before are now achievable by the patented Chance® Helical Pulldown™ Micropile technology.
The Chance® Helical Pulldown™ Micropile is a system for constructing a grout column around the shaft of a standard Helical Pile. The cement grout is pulled down by using a special flowable grout, which is guided by a digger plate that creates a 5-7" void around the shaft of the anchor. The Helical Pulldown™ Micropile, is resistant to buckling in weak surface soils as it is a rigid pile (deflects less at a particular load), and provides additional corrosion protection in aggressive soils. The Helical Pulldown™ Micropile develops additional capacity by combing both end-bearing on the helical plates and skin friction along the rough surface of the grout column. The result is a high capacity pile system.
The pictures above are of a Chance® Helical Pulldown™ Micropile tested to 205 tons. The first picture shows the load test underway. After the load test was performed the test anchor was extracted (second picture) for examination. Pictured third is a close-up of the grout column showing the ridged surface created by the digger plates as the pile is being installed. This rough ridged surface increases the "skin friction" of the pile. The last picture is a cross section of the grout column with the anchor removed, again noting the ridged outer skin of the grout column.
These anchors are offered in 1-1/4", 1-1/2", 1-3/4", and 2" round cornered square shaft anchors with 50 ksi material. The compressive capacity of Helical Pulldown™ Micropiles is over 200kip. All anchors using this system use double corrosion protection. First, by means of grout and second, by using the hot dip galvanized per ASTM A153 (they have an average 2.0 oz/ft^2 (3.0 mils) weight of zinc coating).
Learn more... about New Construction Applications
CASE HISTORIES :
Chance® Helical Pulldown™ Micropiles
BROCHURES :
Chance® Helical Pulldown Micropile(Bulletin 01-0201)
CHANCE® Helical Pier Foundations and Anchoring Systems(Bulletin 01-0505)
TECHNICAL SPECIFICATIONS :
Technical Design Manual 2007(Section 07-0)
