Post-tensioned helical anchors simultaneously spin-drilled and grouted and method therefor
View Patent ↗An assembly and method of simultaneously spin drilling and pressure grouting a helical anchor into the ground vertically, horizontally or at an inclined angle create a continuous grouting configuration inside and outside the helical anchor for its entire depth in the ground. The helical anchor is configured to be partially or completely removed as desired and can be provided at its upper end with a tensioning element to post tension a cementitious foundation structure. A unique spin drilling and grouting assembly continuously provides grout under pressure to the interior of the helical anchor during its spin drilling into the ground. In one embodiment, the pressure grouted helical anchor is used with an upwardly extending tensioning element to reinforce cementitious foundation caps or other concrete support foundations.
1 . A spin drilling and grouting assembly for spin drilling a helical anchor into the ground, said assembly comprising:
a grout body held rigidly in place and having an internal cylindrical space and a grout port in fluid communication with said internal cylindrical space;
a hollow cylindrical grout shank sealingly positioned in the internal cylindrical space of said grout body to freely rotate therein and having a top configured to rigidly engage with a torque motor drive, a bottom configured to rigidly engage with a top of said helical anchor and at least one grout hole, said at least one grout hole aligning with the grout port once every complete 360 degree rotation of the grout shank; and
said grout port configured to transfer grout from a pressurized source through said grout hole and into said hollow cylindrical grout shank upon alignment of the at least one grout hole with the grout port,
said grout shank including a grout plug that completely fills an internal diameter of the grout shank and is located between the at least one grout hole and the grout shank top.
2 . The spin drilling and grouting assembly according to claim 1 , further comprising:
a torque drive connection coupler rotationally secured to said top of said hollow cylindrical grout shank; and
an anchor pipe coupler rotationally secured to the bottom of said hollow cylindrical grout shank.
3 . The spin drilling and grouting assembly in accordance with claim 2 , wherein both said torque drive connection coupler is rotationally secured to said top of said hollow cylindrical grout shank and said anchor pipe coupler is rotationally secured to the bottom of said hollow cylindrical grout shank by nutted shear pin bolts.
4 . The spin drilling and grouting assembly in accordance with claim 1 , wherein the grout port is generally perpendicular to the internal cylindrical space of the grout body.
5 . The spin drilling and grouting assembly in accordance with claim 1 , wherein said hollow cylindrical grout shank includes a plurality of the grout holes equally spaced around a circumference of said grout shank.
6 . The spin drilling and grouting assembly in accordance with claim 1 , further comprising a locator plate projecting outwardly from the grout body to secure the grout body rotationally in place.
7 . The spin drilling and grouting assembly in accordance with claim 6 , wherein the locator plate is rigidly connected to a torque motor housing.
8 . The spin drilling and grouting assembly in accordance with claim 1 , wherein the internal cylindrical space of the grout body has a diameter of between about two inches and about four inches.
9 . The spin drilling and grouting assembly in accordance with claim 1 , wherein the hollow cylindrical grout shank has smooth internal and external surfaces, a length of about twelve inches to about eighteen inches and an outside diameter of about two inches to four inches.
10 . The spin drilling and grouting assembly according to claim 1 , wherein said hollow cylindrical grout shank includes four of the grout holes equally spaced around a circumference of said grout shank.
11 . The spin drilling and grouting assembly according to claim 1 , wherein the hollow cylindrical grout shank is configured to rotate at a speed of between about 10 revolutions per minute and about 40 revolutions per minute.
12 . The spin drilling and grouting assembly according to claim 1 , wherein the helical anchor is configured to remain in place in the ground with the transferred grout.
13 . An apparatus for spin drilling and grouting a helical anchor into the ground, said apparatus comprising:
the spin drilling and grouting assembly in accordance with claim 2 ;
a torque motor having a torque drive rotationally secured to a top of the hollow torque drive connection coupler of the spin drilling and grouting assembly;
at least one pipe section rotationally secured at its top to a bottom of the anchor pipe coupler of the spin drilling and grouting assembly;
at least one helical pipe coupler having an externally mounted helical disc and at least one grout hole in a wall of the coupler connected at its top to a bottom of the pipe section; and
a drill bit rotationally secured to a bottom of said at least one helical pipe coupler.
14 . The apparatus for spin drilling and grouting a helical anchor into the ground in accordance with claim 13 , wherein there is a plurality of the pipe sections and a plurality of the helical pipe couplers fixedly connected alternately in series.
15 . The apparatus for spin drilling and grouting a helical anchor into the ground in accordance with claim 14 , wherein there are four of the pipe sections and four of the helical pipe couplers.