Written by Josh Lindberg on July 24, 2020
Helical piles are an established solution for foundation underpinning, but their applications are as far-reaching as the creativity of an engineer. Helical piles are typically associated with gravity load - force pushing down on the pile. In the project below, helical piles are utilized to support lateral loads, including wind and seismic loads.
To read more on the subject of lateral load, check out Vertical and Battered Helical Pile Groups to Mobilize Lateral Load Capacity.
On October 20, 2019, an EF-3 tornado hit northwest Dallas, Texas causing a trail of damage in the densely-populated area. One local business affected by the storm was Dallas Pistol Club. Certain areas of the gun range were no longer safe because the ballistic barriers were destroyed. New ballistic barriers were to be installed and engineers recommended they be supported by a new deep foundation.
There were numerous challenges on the jobsite that led to CHANCE helical piles being the ideal solution to get the Dallas Pistol Club operating quickly and safely. The installation site was limited access due to load zoned bridges and existing trees. Also, the time frame allotted for the project was less than a week. Helical piles can be installed quickly with a small crew, and unlike concrete, which needs to cure, they could be immediately loaded after installation.
The optimal solution was to install CHANCE RS1275.250 helical piles with two helices, at 18” and 20”, which were installed to an overall length of 30’. The average installation torque for each pile was 60,000 ft.-lbs. Ultimate Compression loads to support the rubber mat barricade was 7 Kips. Due to 10’ or more of the pile terminating above grade, a wind load of 40 psf was considered and required the CHANCE large diameter pipe piles.
Obtaining an accurate soil boring log from a geotechnical report is an important step so engineers can determine the ideal helical pile size and installation depth. A geotechnical investigation was performed on the installation site at Dallas Pistol Club and dense sands were found 8’ - 10’ below existing grade. Ten helical piles were installed for the new ballistic barriers and the project was completed in two days.
Find out how to utilize helical piles to engineer a solution for a project requiring lateral load capacity. Click here to fill out a form and get in touch with your local distributor.
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