Polymer Composite Timber Pile and Methods

Abstract

A support having a timber pile. The support has a sheath positioned about the pile and in spaced relation to the pile to define a gap between the sheath and the pile. The support has a cured polymer disposed between the sheath and the pile and permeated into the pile. A method for reinforcing a structure. A method for building a support for a structure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a nonprovisional of U.S. provisional patent application Ser. No. 63/131,579 filed Dec. 29, 2020, incorporated by reference herein.

FIELD OF THE INVENTION

The present invention is related to a timber pile support for a structure. (As used herein, references to the “present invention” or “invention” relate to exemplary embodiments and not necessarily to every embodiment encompassed by the appended claims.) More specifically, the present invention is related to a timber pile support for a structure that has a sleeve about the timber pile and a cured polymer disposed between the timber pile and the sleeve.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.

Timber piles support bridges, roads, and railways throughout the United States and North America. Timber piling has been a cost effective and reliable method for foundation systems for transportation infrastructure. Being that these piles are made from wood, they are susceptible to long term degradation due to rot, infestation, and stress history. Timber pile repair is often a complicated and slow process, requiring the supported structure to shut down for extended periods of time. In the transportation industry these shutdowns can have a far-reaching economic impact. This repair solution is intended to reduce or eliminate the need for shutdowns during the pile repair process, without compromising the performance of the repair.

Polymer resins have been used for structural repairs since the 1930's in dams, foundations, and structures. Structural epoxy has been proven to be an effective repair and bonding agent. Since the mid 1900's, polymer chemistry has advanced tremendously, allowing us to reduce the curing times and increase the strength of the cured resins. In this pile repair exercise, DE NEEF® Organosol 550 DT of GCP Applied Technologies has been used, a two-component silica-urea polymer. This polymer has a fast reaction time and high initial and final strength. The viscosity of the polymer resin is low enough to allow the resin to permeate into the defects of the damaged timber pile, reinforcing the pile throughout its cross section. The technical data sheet for Organosol 550 DT is incorporated by reference, herein.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to a support. The support comprises a timber pile. The support comprises a sheath positioned about the pile and in spaced relation to the pile to define a gap between the sheath and the pile. The support comprises a cured polymer disposed between the sheath and the pile and permeated into the pile.

The present invention pertains to a method for reinforcing a structure. The method comprises the steps of moving a support to a desired position below the structure. The support comprises a timber pile, a sheath positioned about the pile and in spaced relation to the pile to define a gap between the sheath and the pile, and a cured polymer disposed between the sheath and the pile and permeated into the pile. There is the step of placing the support upright above the structure.

The present invention pertains to a method for building a support for a structure. The method comprises the steps of placing a sheath about a timber pile so a gap is defined between the sheath and the pile. There is the step of filling the gap between the sheath and the pile with a polymer. There is the step of allowing the polymer to permeate into the pile. There is the step of letting the polymer cure.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a representation of the support of the present invention.

FIG. 2 is an overhead view of a representation of the support.

FIG. 3 is a perspective view of a representation of a timber pile.

FIG. 4 is a perspective view of a representation of the support with a sheet.

FIG. 5 is a perspective view of a representation of the support with the form.

FIG. 6 is a perspective view of a representation of the form.

FIG. 7 shows pile A.

FIG. 8 shows pile A with reinforcement.

FIG. 9 shows pile A cured.

FIG. 10 shows the top of pile B.

FIG. 11 shows pile B with reinforcement.

FIG. 12 shows pile B cured.

FIG. 13 shows the top of pile 2.

FIG. 14 shows the bottom of pile 2.

FIG. 15 shows the side of pile 2.

FIG. 16 shows a top void of pile 2.

FIG. 17 shows a void with reinforcement of pile 2.

FIG. 18 shows pile 2 ready to be treated.

FIG. 19 is a graph of pile group 1 load versus displacement.

FIG. 20 is a graph regarding cyclic testing of pile B.

FIG. 21 is a graph of pile group 2 load versus displacement.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to FIGS. 1-3 thereof, there is shown a support 10. FIGS. 1 and 2 show a perspective view and an overhead view, respectively of the support 10. The support 10 comprises a timber pile 12. FIG. 3 shows the pile 12 itself. The pile 12 is damaged with voids 15 from wood that has rotted or been chipped away. The support 10 comprises a sheath 14 positioned about the pile 12 and in spaced relation to the pile 12 to define a gap 16 between the sheath 14 and the pile 12. The support 10 comprises a cured polymer 17 disposed between the sheath 14 and the pile 12 and permeated into the pile 12.

The sheath 14 may be a wire mesh 18 or a sheet 20, as shown in FIG. 4. The support 10 may include metal bars 22 disposed between the pile 12 and the sheath 14 and in the cured polymer 17. The pile 12 may have holes 24 and the cured polymer 17 is disposed in the holes 24. The support 10 may include spacers 26 disposed between the pile 12 and the sheath 14. To facilitate the repair of the pile 12, with the polymer 17, a form 38 may be positioned around the reinforced pile 12, as shown in FIGS. 5 and 6. FIG. 6 shows the form 38 which fits around and snaps together to hold the polymer 17 in and about the pile 12 after the polymer 17 has been poured or applied to the reinforced pile 12 while the polymer 17 cures.

The present invention pertains to a method for reinforcing a structure. The method comprises the steps of moving a support 10 to a desired position below the structure. The support 10 comprises a timber pile 12, a sheath 14 positioned about the pile 12 and in spaced relation to the pile 12 to define a gap 16 between the sheath 14 and the pile 12, and a cured polymer 17 disposed between the sheath 14 and the pile 12 and permeated into the pile 12. There is the step of placing the support 10 upright love the structure.

The present invention pertains to a method for building a support 10 for a structure. The method comprises the steps of placing a sheath 14 about a timber pile 12 so a gap 16 is defined between the sheath 14 and the pile 12. There is the step of filling the gap 16 between the sheath 14 and the pile 12 with a cured polymer 17. There is the step of allowing the polymer to permeate into the pile 12. There is the step of letting the polymer cure.

In the operation of the invention, a total of eight damaged timber piles were selected for repair. Various repair techniques were used and are discussed below. The repaired timber piles were sent to the NIOSH facility in Pittsburgh, Pa. for compressive strength testing, and cyclic creep testing.

A. Pile Group 1

Two piles were initially selected for repair and testing. The basis for design was to incorporate vertical and confining steel reinforcement into the polymer 17 to create a composite repair that would account for compression and tension forces. The timber pile 12 foundation systems include horizontal bracing to address bending and buckling, therefore non-slender column design principles were used in the analysis. The value of the compressive strength of concrete was replaced by the compressive strength of the polymer 17. Tin sheeting 20 was used to encase and contain the Organosol 550 DT in the pile 12 repair area during curing. The Polymer 17 bonded to the tin sheeting 20, and was not removed prior to testing.

1. Pile A

Length: 3′ 8″

Diameter: 17″

Design: The pile 12 was wrapped with welded 9 gage wire 18 and 4 #6 rebar 22 were installed vertically. The wire was placed and spaced roughly in the center of a 2″ thick zone that would be filled from the top with the Organosol 550 DT. Tin sheeting 20 was used to encase the timber pile 12 and steel reinforcement and contain to Organosol 550 DT in the repair area during curing. The Organosol 550 DT was installed in two lifts, from the bottom up. The polymer 17 permeated into the timber pile 12 utilizing gravity head. This was facilitated by ¾″ diameter holes 24 that were drilled through the timber pile 12 cross section to allow thorough penetration of the Organosol 550 DT into the timber pile 12. See FIGS. 7-9.

2. Pile B

Length: 3″ 9″

Diameter: 19″

Design: The pile 12 was wrapped with welded 9 gage wire and 6 #6 rebar were installed vertically. The wire was placed and spaced roughly in the center of a 2″ thick zone that would be filled from the top with the Organosol 550 DT. Tin sheeting was used to encase the timber pile 12 and steel reinforcement and contain to Organosol 550 DT in the repair area during curing. The Organosol 550 DT was installed in two lifts, from the bottom up. The polymer permeated into the timber pile 12 utilizing gravity head; this was facilitated by ¾″ diameter holes 24 that were drilled through the timber pile 12 cross section to allow thorough penetration of the Organosol 550 DT into the timber pile 12. See FIGS. 10-12.

B. Pile Group 2

Based on the results from the testing of pile group 1, the amount of steel reinforcement and polymer cover was reduced in pile group 2. Six piles were selected for further testing, as outlined below. Plexi-glass sheeting was used to encase and contain the Organosol 550 DT in the pile 12 repair area during curing. A release agent was used to prevent the polymer from bonding to the plexi-glass sheeting. The polymer permeated into the timber piles utilizing gravity head, this was facilitated by ¾″ diameter holes 24 that were drilled through the timber pile 12 cross section to allow thorough penetration of the Organosol 550 DT into the timber pile 12.

1. Pile #1

Length: 8′ 2″

Diameter: 16″

Design: The pile 12 was wrapped with welded 9 gage wire. The wire is provided in 48″ wide sheets and approximately 60″ of length was required. Two wire sheets were required. The wire was placed and spaced roughly in the center of a 1″ thick zone that would be filled from the top with the Organosol 550 DT.

2. Pile #2

Diameter: 13.5″

Design: The pile 12 was wrapped with welded 9 gage wire and four #3 rebar were installed vertically. The wire is provided in 48″ wide sheets and approximately 60″ of length was required. Two 48′×60″ sheets were required. The wire was placed and spaced roughly in the center of a 1″ thick zone that would be filled with the Organosol 550 DT. See FIGS. 13-18.

3. Pile #3

Diameter: 13.5″

Design: The pile 12 was wrapped with welded 9 gage wire and four #3 rebar hoops were installed directly against the pile 12. The wire is provided in 48″ wide sheets and approximately 60″ of length was required. Two 48″×60″ sheets were required. The wire was placed and spaced roughly in the center of a 1″ thick zone that would be filled with the Organosol 550 DT.

4. Pile #4

Diameter: 13″

Design: The pile 12 was wrapped with a light woven wire lath and four #3 rebar hoops were installed directly against the pile 12. The wire is provided in 36″ wide sheets and approximately 60″ of length was required. Three 36″×60″ sheets were required. The wire was placed and spaced roughly in the center of a 1″ thick zone that would be filled with the Organosol 550 DT.

5. Pile #5

Length: 7′ 4″

Diameter: 13″

Design: The pile 12 was drilled in three locations (18″; 54″ and 70″ from the bottom) with a ⅝″ drill bit to a depth of 11 inches. The outside of the pile 12 was wrapped with two layers of stretch wrap before the mechanical packers were then set in the outer 2 inches of each hole. Starting at the bottom packer the Organosol 550 DT was injected until resin was flowing out of the pile 12 and the stretch wrap could no longer contain it. Then the next packer was injected.

6. Pile #6

Length: 8′ 2″

Diameter: 13″

Design: The pile 12 was wrapped with a light woven wire lathe directly against the pile 12. The wire lathe provided a ⅜″ ½″ spacer for the outer acrylic molding sheet 20. The wire is provided in 36″ wide sheets and approximately 60″ of length was required. Three 36″×60″ sheets were required. The space was filled with the Organosol 550 DT.

III. Repair Testing

A. Testing Methods

Testing for both pile groups was conducted at the NIOSH facility in Pittsburgh, Pa. Testing was conducted in a Mine Roof Simulator load cell (MRS), with a loading capacity of 3,000,000 pounds. Leveling plywood and shims were used to align the timber piles vertically in the testing apparatus. A seating load was applied to account for the deformation due to the plywood crushing during loading. Pile group 1 was tested with the construction encasement remaining on the pile 12, pile group 2 was tested without the construction encasement. Piles were loaded vertically, at a rate of ½″ per minute, until cyclic loading was reached or until failure. The anticipated load for each pile 12 was determined to be 80 kips. Applying a factor of safety of 1.5, 120 kips was determined to be our cyclic creep test loading. In pile group 1 only pile B was cyclically loaded before loading to failure. All piles in pile group 2 were cyclically loaded before loading to failure. Cyclic loading was performed by loading the pile 12 to 120 kips, holding that load for 30 seconds and then releasing the load. 100 cycles of loading were applied to each pile 12. After cyclic loading, the piles were loaded until failure.

B. Testing Results

1. Pile Group 1

Pile A was loaded to failure, which was observed to be a crushing failure at just below midpoint of the pile 12. Pile 12 failure occurred at approximately 500 kips, with approximately 3.25″ of deformation.

Pile B was cyclically loaded up to 120 kips (FIG. 33), with a 30 second hold at 120 kips, over 100 cycles. After cyclic loading was completed, pile B was loaded to failure, which was observed to be a crushing failure at just below midpoint of the pile 12. Pile 12 failure occurred at approximately 575 kips, with approximately 1.75″ of deformation. See FIGS. 19 and 20.

2. Pile Group 2

All piles were cyclically loaded to 120 kips over 100 cycles before loading to failure. Creep deformation was negligible on all piles except for pile #5. Pile #5 failed in the first cyclic loading cycle at approximately 120 kips. See FIG. 21.

Based on the results from the testing at the NIOSH facility, all piles tested, excluding pile #5, met or exceeded the anticipated performance requirements for the pile 12 repair.

Pile group 1 withstood much higher loading conditions than anticipated in real world settings, for this reason a leaner repair section was applied to pile group 2. Pile #1 in pile group 2 withstood the highest loading condition and was constructed using the simplest method. Pile #2 in pile group 2 exhibited high strength, and very good performance after initial failure, indicating that this repair configuration provided additional resiliency to the pile 12 repair. Pile #3 Exhibited slightly lower strength and resilience than Pile #2. Pile #4 exhibited slightly lower strength and resilience than Pile #3. Pile #5 did not achieve loading requirements, failing under initial cyclic loading. Pile #6 Exhibited high strength but low resilience.

Based on the installation methodology and testing results for these two pile groups, it appears that Pile #2 and Pile #3 performed within the scope of this repair. Pile #2 exhibited high strength and the ability to carry reasonably high loads past its failure point, which makes Pile #2 the optimum candidate for replication based on its testing performance. Pile #3 also exhibited high strength and the ability to carry load past its initial failure point.

Polymer may be applied by being poured into the prepared pile 12 or applied under pressure depending on the application. Primarily the polymer is gravity fed or poured in, however based on the pile 12, small amounts of polymer may need to be applied under small amounts of pressure. The polymer 17 is a two-part component that is mixed at a mixing nozzle then pumped into the casing around the pile 12 and allowed to permeate the pile 12 and flow through the holes 24 and cracks before it cures. If the polymer 17 is poured into the prepared pile 12, the polymer would be mixed in a static mixer before its poured into the pile 12.

Typically, a form 38 is used that attaches around the pile 12 that holds the polymer 17 in and provides the required spacing around the pile 12. The form 38 can be removed if needed, however it is recommended the form 38 stay in place as a second skin to eliminate UV light and weather. When applicable, the soil or ground acts as the bottom of the form 38. If the repair of the pile 12 is isolated, the bottom of the pile 12 would be placed with tin or plastic.

To make sure the polymer 17 fills the holes 24 drilled into the timber pile 12, typically head pressure of the polymer 17 is relied on for the polymer 17 to permeate the pile 12, but there could be times that the polymer 17 needs to be applied under pressure to achieve permeation. When polymer 17 needs to be applied under pressure, a pump is connected to a nozzle which fits into the holes 24 to pump the polymer into the holes 24. The holes 24 are filled under pressure with the polymer 17 until all the holes 24 are filled. Then the polymer 17 is poured into the pile 12.

The number of holes 24 drilled perpendicular to or parallel to timber pile 12 longitudinal center of axis is based on the current condition of the rotting pile 12. Typically, this would be 10″-12″ rotating 90 degrees as a repairer works up or down the pile 12. Holes 24 would be drilled completely through the pile 12. For instance, looking down on the pile 12, a hole would be drilled through at 12 o'clock to 6 o'clock. Then a hole would be drilled into the pile 12 perpendicularly at 3 o'clock to 9 o'clock. Height between the holes 24 would be 10″-12″. Holes 24 may need to be drilled at an angle to miss or avoid hardware or other timber framing structures of a bridge or a pier, or to target a large void or crack in the pile 12 that would need to be repaired.

A timber pile 12 is able to be repaired while the pile 12 is still in place supporting a structure. Typically, a header that would sit on the pile 12 would still allow room to pour the polymer in from the top. If access wasn't available, a hole would be drilled in the top of the form about the pile 12 to pump the polymer in. The tin sheet 20 or the molded plastic forms can remain in place or be removed. It is recommended they stay in place as a secondary form of protection from UV light and weather.

When wire 18 was placed in the center of a 2″ think zone, it means the form 38 was set off the actual pile 2″ and wire mesh 18 was run around the pile 12 and set between the pile 12 and outer form 38. A modeled form 38 designed to clip around the pile 12, as shown in FIG. 6.

Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.

Claims

1. A support comprising:

a timber pile;

a sheath positioned about the pile and in spaced relation to the pile to define a gap between the sheath and the pile; and

a cured polymer disposed between the sheath and the pile and permeated into the pile.

2. The support of claim 1 wherein the sheath is a wire mesh or a sheet.

3. The support of claim 2 including metal bars disposed between the pile and the sheath and in the cured polymer.

4. The support of claim 3 wherein the pile has holes and the cured polymer is disposed in the holes.

5. The support of claim 4 including spacers disposed between the pile and the sheath.

6. A method for reinforcing a structure comprising the steps of:

moving a support to a desired position below the structure, the support comprising a timber pile, a sheath positioned about the pile and in spaced relation to the pile to define a gap between the sheath and the pile, and a cured polymer disposed between the sheath and the pile and permeated into the pile; and

placing the support upright below the structure.

7. A method for building a support for a structure comprising the steps of:

placing a sheath about a timber pile so a gap is defined between the sheath and the pile to create a reinforced timber pile;

filling the gap between the sheath and the pile with a polymer;

allowing the polymer to permeate into the pile; and

letting the polymer cure.

8. The method of claim 7 including the step of positioning a form about the reinforced timber pile.

9. The method of claim 8 wherein the placing step includes the step of placing the sheath about the timber pile while the timber pile is in place supporting the structure.