Cementitious foundation cap with post-tensioned helical anchors

摘要

A post-tensioned concrete cap foundation has helical anchors with pipes having several helical discs welded around the pipe perimeter to spin drill deep into subsurface soils or other soft materials with holes in the pipe for high pressure-grouting in place. The helical anchor pipes include a tensioning element for pulling and post-tensioning the helical anchor. The helical anchors are tension anchors which can be converted to compression anchors. The helical anchors in tension serve to pull the foundation cap down to compress the underlying soil while the compression anchors limit the maximum settlement of the concrete foundation cap. The foundation also includes perimeter-forming and interior corrugated metal pipes with upper and lower sleeved horizontally extending radial bolts that are secured to the pipes and post-tensioned to provide lateral foundation compression.

主权项

1. A post-tensioned concrete foundation for supporting on its upper surface a tall tower or a structure subject to heavy load and high upset forces, said foundation comprising:
a generally horizontal concrete foundation cap for supporting a tall tower or other structure from an upper surface and having a lower surface engaged with a ground surface; and a plurality of generally vertical post-tensioned hollow bar helical anchors circumferentially spaced from one another, each of said hollow bar helical anchors including at least one hollow bar helical anchor pipe extending downwardly from said concrete foundation cap lower surface into surrounding soil underneath said concrete foundation cap, and a tensioning element coupled to an upper end of said at least one hollow bar helical anchor pipe and extending through the concrete foundation cap, an upper end of each of said tensioning elements terminating above said concrete foundation cap upper surface, said tensioning elements pulling said cap downwardly and pulling the at least one hollow bar helical anchor pipe of each hollow bar helical anchor upwardly to post tension said foundation cap and said hollow bar helical anchors.