Method for Installing a Helical Pier with Polyurthane Resin Grout
A method for installing a helical pier using a polyurethane resin grout that results in a support structure capable of bearing heavy loads and exhibiting high lateral strength which is also nontoxic and non-hazardous to the environment
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1. Field of Invention
The present invention relates to a method for the installation of a helical pier, or screw pile, and injecting a grout into the pile.
2. Description of Related Art
Screw piles have long been commonly used in connection with foundation underpinning, pipeline tie-downs and in other applications. They are generally used as support structures for heavy loads.
In one known embodiment, a screw pile consists of an open-ended tubular shaft having one or more helixes externally mounted thereon adjacent to its pointed lower end. The shaft typically comprises a bottom anchor section carrying the helixes and one or more extension sections. The shaft has means, such as pin holes, at its upper end, for insertion of locking pins to connect the shaft with a drive head assembly which functions to rotate the pile into the ground.
A screw pile will be characterized by load-carrying capacities once implanted in the ground. The load-carrying capacity of a screw pile can be increased by increasing its length and/or diameter or increasing the number of helixes. In addition, the nature of the ground into which the pile is implanted will also affect the load-carrying capacity of the pile.
A problem inherent with screw piles is, due to their vertical shape and the fact that helixes loosen and disturb the soil as they wind therein, the screw piles do not offer lateral stability that is comparable to other foundations such as concrete footers. For this reason, it is known to inject grout, such as cement, into the borehole created by the screw pile to strengthen and harden the soil adjacent to the screw pile and improve its lateral stability.
The problems inherent with known methods of injecting grout into a screw pile borehole include a lack of strength necessary to support certain heavy loads an the environmental issues created when using a toxic or hazardous grouts. There is accordingly a need for a method for installing a screw pile using a grout that is strong enough to allow the pile to support heavy loads, provide sufficient lateral stability, and also be nontoxic.
SUMMARYThe present invention is a method for installing screw piles into a target subsurface formation and then stabilizing them with a polyurethane resin grout. In one embodiment, a screw pile is installed into a target subsurface formation using known a means, e.g., by rotationally driving the screw pile into the ground to penetrate the subsurface formation until the desired depth is achieved. Once the screw pile is set in place, injection tubes are then driven into the subsoil so that tube openings are positioned within the borehole and near the bottom anchor. Liquid polyurethane resin is then injected through the tube. As the borehole fills with resin, the tubes are withdrawn from the subsoil. The resin then hardens and stabilizes the screw pile in place.
In an alternative embodiment of the present invention, a borehole may be predrilled using a drilling rig, with the screw pile then rotationally driven into the base of the borehole. Liquid polyurethane resin is then pored or sprayed (e.g., via spray-foam equipment) into the borehole and allowed to cure. The result is a pile that can bear heavy loads and exhibits high lateral strength using a method and materials that are nontoxic and non-hazardous to the environment.
Referring to
Claims
1. A method for installing a helical pier with polyurethane resin grout, the method comprising the steps of:
- (a) installing said helical pier in a target location;
- (b) filling the area adjacent to said helical pier with a polyurethane resin grout; and
- (c) allowing said polyurethane resign grout to cure.
2. The method for installing a helical pier according to claim 1, further comprising, before step (b): drilling a borehole at said target location.
3. The method of installing a helical pier according to claim 1, further comprising, before step (b): inserting one or more injection tubes at said target location and blowing said polyurethane resign grout near the helixes of said helical pier.
Type: Application
Filed: Feb 5, 2013
Publication Date: Sep 19, 2013
Applicant: Concrete Alternatives & More, Inc. (Drums, PA)
Inventor: Robert G. Tarapchak (Drums, PA)
Application Number: 13/759,426
International Classification: E02D 7/00 (20060101);