The Grouted Helical Micropile process begins with the installation of a standard helical lead section, round or square shaft, followed by displacement plates and extensions.
The Screw Anchor is fixed into position with the application of torque to the shaft using an excavator mounted or handheld drive head. As the screw turns, the lead section advances downward with minimal disturbance to the underlying soil.
A displacement plate is then slipped over the shaft as a square or round shaft extension is added and bolted into place. Torque is again applied to the shaft to drive the displacement plate and extension into the soil. As the pile advances,the displacement plate pushes the soil outward to create a cylindrical void around the shaft. A Grout Reservoir at the surface provides the gravity flow of neat Portland cement to fill the void created by the displacement plates.The reservoir can be created with a variety of different materials, but is often simply a steel or PVC pipe or laminated fiber tube.
Grout from the Reservoir is drawn down into the void to encapsulate the shaft. Additional displacement plates and extensions can be added to achieve the required depth specifications. Grouted helical Micropiles have been installed over 100 feet deep with grout columns ranging from 4” - 10” in diameter, with the 6” grout column being the most common.
The deeper the pile, the more capacity can be derived from the skin friction on the grout encased shaft. The standard helical lead section provides significant load bearing support on the bearing plates while the grout column increases capacity while alleviating all design concerns regarding lateral, buckling, or corrosion.
Cased
Grouted Helical Pulldown Micropiles are available from Danbro Distributors in both cased and Steel or PVC encased formats. The Cased version provides less capacity from skin friction on the column but increases the section modulus and can be load tested to determine actual overall capacity. The cased Grouted Helical Micropile also allows for the use of helical piles above grade.In given circumstances, Uncased grouted helical piles can be employed below grade while transitioning to the cased version above the ground.
The Danbro Installer network has installed more cased and uncased Grouted Helical micropiles, in various soil environments and diverse applications, than any other installer group in the country. At Danbro we say, “When In Doubt, Grout” Still have questions? We can help you decide if grouted helical piles or traditional helical piles are the right fit for your next project.
The Danbro Team is with you from start to finish and can provide everything from value engineering support, material quotes, p.e. Sealed designs, product shipping and on-site support.
Visit Danbro.com for more information on Grouted Helical Pulldown Micropiles and our full line of deep foundation solutions.