VA War Memorial featured in Foundation Drilling Magazine

Subsurface Construction is honored to have the Virginia War Memorial as a Technical Featured article in Foundation Drilling Magazine July 2018, a publication of the Association of Drilled Shaft Contractors (ADSC). Subsurface designed and constructed a permanent anchored secant pile wall and a temporary soil nail wall for the expansion project.

For the secant pile wall, Subsurface teamed up with the experts at Equipment Corporation of America (ECA) to supplement its own experience with this construction method. From the initial bidding process to the wall’s construction, Subsurface worked closely with ECA’s Gordian Ulrich and Jeff Harmston to assess the appropriate drill rig and tooling needs. Casing was required due to the soft ground, presence of groundwater, and accuracy of the alignment of the piles. Subsurface used a Bauer BG 20 rig with 35-inch sectional casing and an earth auger for secant pile installation. The process alternated between 1-2 days of primary pile construction and 1-2 days of secondary pile construction spaced at 6 ft. on center. The construction of the secant pile wall as a success and was completed two weeks ahead of schedule.

For the temporary shoring, Subsurface designed and installed a hybrid pipe pile and conventional shotcrete soil nail wall had an overall retained height of approximately 35 ft. A primary challenge with design and installation was coordinating the location of soil nails (+/-45 ft. long) to miss existing utilities and soil nails on the opposing side of an outside corner. Subsurface was concerned that despite engineering the nails to miss, slight drilling deviations would inevitably cause damage to previously installed nails. To mitigate this risk, significant effort was spent on the layout of each
soil nail while continuously monitoring during drilling to ensure the original alignment was maintained. In addition, the shotcrete facing was not applied until all drilling within the zone of opposing nails was complete for each lift.

To learn more about the installation, project challenges and modeling/measuring of deflections please read more:

Foundation Drilling Magazine