WO2016095052A1

WO2016095052A1 - Composite sleeve for piles

Info

Publication number: WO2016095052A1
Application number: PCT/CA2015/051346
Authority: WO
Inventors: Guangfeng QU; Sean HINCHBERGER; Rob Lydan
Original assignee: Hatch Ltd.
Priority date: 2014-12-19
Filing date: 2015-12-18
Publication date: 2016-06-23
Also published as: WO2016095052A9

Abstract

A composite sleeve system, covering a pile, serves to reduce adfreeze uplift load on the pile. The sleeve system consists of a protection casing and a rigid sleeve, covering the pile and extends below the frost depth. The sleeve material may be selected to have a low-friction outer surface, a sufficient wall thickness to resist the adfreeze force. In accordance with other aspects, a top lock may be installed above the top of the sleeve to control the upward jack-up displacement of the sleeve and the consequently potential damage to the pile cap or foundation. The casing is to protect the sleeve during installation. In service life, the casing is allowed to be jacked up by adfreeze force and is expected to be squeezed/yielded at the top lock location. The rigid sleeve is permanent and serves to minimize adfreeze force transferred to the pile.

Description

COMPOSITE SLEEVE FOR PILES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001 ] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/094,950 filed December 19, 2014, U.S. Provisional Patent Application No. 62/097,325 filed December 29, 2014 and U.S. Provisional Patent Application No. 62/121 ,201 filed February 26, 2015. The contents of all three documents are incorporated herein by reference.

FI ELD

[0002] The present application relates generally to piles and, more specifically, to a composite sleeve system for piles.

BACKGROUND

[0003] A pile may be defined as a steel pipe post or H-beam driven vertically into the bed of a soft/firm ground to support the foundations of a structure. Piles are known to have many applications. For example, piles may be used to support structures in use in solar farms. Furthermore, the structures that piles may be used to support include pipeline structures, communication towers, buildings, bridges and others.

[0004] In northern regions such as Canada, Alaska, Siberia, etc., the foundation soil can freeze to a particular depth due to frost actions as influenced by cold ambient air temperature. A frost heave action may develop a significant "adfreeze uplift" load that may be transferred from frozen soils to piles, as described in Chapter 13 of the Canadian Foundation Engineering Manual, 4th edition, which is hereby incorporated herein by reference. This adfreeze uplift load is usually taken into account when designing light weight structures for use in cold climates.

SUMMARY

[0005] A composite sleeve system, as described herein, includes a protection casing covering a rigid sleeve, which is adapted to cover the outside perimeter of a pile. The sleeve system is preferred to extend from a ground surface to below a frost depth. The rigid sleeve, in various aspects, has a low friction outer surface, a sufficient wall thickness to resist the adfreeze force, a close spacing between the sleeve inner surface and the pile outside surface. The casing is to protect the sleeve from scratching the outside surface during installation. The casing has a low friction outer surface and a close spacing between the casing inner surface and the sleeve outside surface. In accordance with other aspects, a top lock may be installed above the top of the sleeve to control the upward jack-up displacement of the sleeve and the consequently potential damage to the pile cap or foundation.

[0006] According to an aspect of the present disclosure, there is provided a composite sleeve system. The system includes a protection casing and a rigid sleeve covering an outside perimeter of a pile.

[0007] Other aspects and features of the present disclosure will become apparent to those of ordinary skill in the art upon review of the following description of specific implementations of the disclosure in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Reference will now be made, by way of example, to the accompanying drawings which show example implementations; and in which:

[0009] FIG. 1 illustrates, in a partial, vertical cross-sectional view, a pile with a composite sleeve system (including a protection casing and a rigid sleeve) and a top lock for helical piles in accordance with an embodiment of the present application;

[0010] FIG. 2 illustrates, in a partial, vertical cross-sectional view, a pile with a composite sleeve system, a driving shoe and a top lock for helical piles and other types of piles in accordance with an embodiment of the present application;

[001 1 ] FIG. 3 illustrates, in a plan cross-sectional view, a configuration of a driving shoe suitable for use in the pile and the composite sleeve system of FIG. 2 in accordance with an embodiment of the present application; [0012] FIG. 4A illustrates, in a plan cross-sectional view, a configuration of a panel type driving shoe suitable for use in the pile and the composite sleeve system of FIG. 2 in accordance with an embodiment of the present application;

[0013] FIG. 4B illustrates, in a side view, a triangle panel configuration for the driving shoe of FIG. 4A in accordance with an embodiment of the present

application;

[0014] FIG. 4C illustrates, in a side view, a rectangle panel configuration for the driving shoe of FIG. 4A in accordance with an embodiment of the present

application;

[0015] FIG. 5A illustrates, in a plan cross-sectional view, the composite sleeve system consisting of a casing and a rigid sleeve covering the pile of FIGS. 1 and 2, where the sleeve has a smooth inner surface in accordance with an embodiment of the present application;

[0016] FIG. 5B illustrates, in a plan cross-sectional view, the rigid sleeve of FIGS. 1 and 2 with longitudinal ribs at the inner surface in accordance with an embodiment of the present application;

[0017] FIG. 6A illustrates a first portion of a table of materials suitable for use in the sleeve system of FIGS. 1 , 2 and 6; and

[0018] FIG. 6B illustrates a second portion of a table of materials suitable for use in the sleeve system of FIGS. 1 , 2 and 6.

DETAILED DESCRI PTION

[0019] In the past, designers have taken various measures to account for adfreeze uplift load. In one measure, the designers place a foundation under frost depth. In another measure, the designers design a heavy-duty pile to resist the adfreeze uplift load. These two measures are often expensive and may, sometimes, be impractical due to specific site conditions. [0020] It is known to add heating lines to a pile system to maintain the above- zero Celsius temperature to avoid adfreeze uplift loading, as shown, for example, in U.S. Patent Number 7,635,238 to Colbert.

[0021 ] It is also known to place board thermal insulation near the ground surface and, thereby, protect soil around the pile from freezing. Various design approaches for the insulation thickness and covering area can be found in Robinsky E.I., Bespflug K.E., Design of Insulated Foundations, Journal of the Soil Mechanics and Foundations Division, Vol. 99, No. 9, September 1973.

[0022] It is further known to pre-drill a hole and backfill the hole with sand slurry and a plastic cover adhering to the pile, as disclosed in Canada Patent Number 1 ,254,393 to Takeda et al.

[0023] It is still further known to fasten a tubular sheath to a pile and fill the volume between the sheath and the pile with an anti-freezing fluid. This approach, which also involves a pre-drilled hole backfilled with a sand slurry, is disclosed in US Patent Number 4,585,681 to Kidera et al.

[0024] It is still further known to place a slidable sleeve, which "slides along the screw pile during the inevitable movement that naturally occurs over the course of time" (see the description by Techno Metal Post at

http://www.technometalpost.com/en/products/exclusive-sleeve/ and the animation video at the webpage showing the working mechanism). The sleeve in this approach was further specified in the part manual (TP-P001 revision 07, dated 2013-12-04) as a thin wall polyethylene pipe with a wall thickness from approximately 1 mm to 2 mm for a pile with a diameter from 1 7/8" (48 mm) to 5 ½" (140 mm).

[0025] In general, these referenced solutions may either be considered not to be practical in construction or considered to have design flaws. The first two referenced solutions may be considered to be too expensive, especially for the heating and insulation systems, and may become impractical for piles in remote areas. The first two referenced solutions include a pre-drilled hole, which required crew and equipment for construction and often need a permit for the disposal of excavated soil. As a result, the impact on a given construction schedule and cost would be considerable. [0026] In addition, the configuration of the slidable sleeve may have a fatal flaw in the design, particularly for permanent piles. The sleeve will be jacked up each winter and won't be able to slide downward to its original position simply due to the friction resistance from soils. As such, the pile, at least its lower portion, will be exposed to soil eventually.

[0027] FIG. 1 A illustrates a pile 1 in soil 12. A sleeve system includes a protection casing 20 and a permanent rigid sleeve 2 that surrounds the pile 1 and extends from a sleeve top 9 to a sleeve bottom 10. Conveniently, the casing 20 may be seen to minimize scratching of and damaging to the outer surface of the sleeve 2, which scratching and damaging may be caused by soil during pile installation. The sleeve top 9 may be preferably above the ground surface 7 and the sleeve bottom 10 may be preferably at the top surface of a helix 19. The sleeve system may include a top lock 3 adapted for preventing the rigid sleeve 2 from jacking up and damaging the pile cap or foundation (not shown). The top lock 3 may be implemented as a bolt installed at the pin holes 22 in the pile 1 , or as a steel collar/bar welded to the pile 1 , or as a clamp. If any spacing (Hs) is left between the sleeve top 9 and the top lock 3, the sleeve extension at bottom (Hb) shall be greater than the spacing (Hs) to ensure the protection of the pile 1 within the full frost penetration depth (H) after the adfreeze jack-up within the allowable spacing (Hs).

[0028] The rigid sleeve 2 may have one or more optional features.

[0029] For one example feature, a soil-facing surface of the rigid sleeve 2 may be associated with low friction and with low ice-bonding strength between the rigid sleeve 2 and the frozen soil 12. This feature, a combined effect of low friction and ice-bonding strength, shall limit the adfreeze stress less than 100 kPa (design value for steel-soil interface), and preferably in a range that extends from 0-50 kPa.

[0030] For a further example feature, the rigid sleeve 2 may exhibit a sufficient strength by specifying a minimum wall thickness. That is, the wall thickness of the rigid sleeve 2 shall be selected as per the following formula: sleeve wall thickness > (factored adfreeze load / (factored sleeve material compression strength x n x sleeve nominal diameter) ). In addition, the shear strength of the rigid sleeve 2 should allow for the rigid sleeve 2 to be torqued into the soil 12 without breaking. It should be noted that the rigid sleeve 2 shall satisfy the above performance requirement in low temperatures, which may be encountered at the site.

[0031 ] The casing 20 may have one or more optional features. The casing 20 is intended to protect the sleeve during installation. In service life, the casing 20 may be allowed to be jacked up by adfreeze force and is expected to be squeezed at the top lock location. When the casing 20 is squeezed at the top lock location, the casing 20 may yield in a predictable and acceptable manner. The rigid sleeve 2 may be considered to be permanent and may serve to minimize adfreeze force transferred to the pile 1 .

[0032] For one example feature, similar to the rigid sleeve 2, a soil-facing surface of the casing 20 may be associated with low friction and with low ice-bonding strength between the casing 20 and the frozen soil 12.

[0033] For a further example feature, the casing 20 may have an appropriate wall thickness to tolerance the installation and to minimize the cost.

[0034] FIG. 6A illustrates a first portion 70A of a table that lists the materials suitable for use for the rigid sleeve 2 and the casing 20. FIG. 6B illustrates a second portion 70B of the table that lists the materials suitable for use for the rigid sleeve 2 and the casing 20. Indeed, a material for the rigid sleeve 2 and the casing 20 may be formed as a composite of materials comprising two or more of the materials listed in the table portions 70A, 70B, with or without metal wire reinforcement.

[0035] FIG. 2 illustrates a pile 1 in soil 12. A composite sleeve system extends from a sleeve top 9 to a sleeve bottom 10. The sleeve bottom 10 may be preferably a nominal distance below the frost depth 8.

[0036] Below the sleeve bottom 10, an optional driving shoe 6 may be fastened to the pile 1 . The driving shoe 6 is preferably an oversized steel pipe welded to the pile 1 below the sleeve bottom 10. Weld locations 14 are identified in FIGS. 3 and 4A. For the pile 1 driven by rotation installation techniques, the driving shoe 6 may be implemented as a steel plate 16 with driving panels 13 that may be used for hard soil conditions or for long sleeves. Various driving panels 13 are shown in FIGS. 4A, 4B and 4C. Each driving panel 13 can be triangular (see FIG. 4B) or rectangular (see FIG. 4C).

[0037] The optional driving shoe 6 may be particularly useful when the pile 1 , the casing 20 and the rigid sleeve 2 are being driven into relatively hard soil. The optional driving shoe 6 may be seen to minimize damage to the rigid sleeve 2 during driving the rigid sleeve 2 into the soil 12. It should be understood that the outside diameter of the driving shoe 6 should be larger than the outside diameter of the rigid sleeve 2.

[0038] The spacing between the inner wall of the rigid sleeve and the pile surface shall be minimized as much as the manufacture and installation tolerance allows. This spacing may be preferably less than 4 mm to minimize lateral movement of the pile and potential fatigue effect.

[0039] In aspects of the present application, an inner wall of the rigid sleeve 2 may be smooth, as shown in FIG. 5A. In other aspects of the present application, the inner wall of the rigid sleeve 2 may have longitudinal ribs 18, as shown in FIG. 5B.

[0040] The longitudinal ribs 18 may be seen to act to increase resistance to lateral movement of the pile 1 within the rigid sleeve 2. It should be understood that some tolerance between the outer dimensions of the pile 1 and the inner dimensions of the rigid sleeve 2 allow for the rigid sleeve 2 to be installed over the pile 1 .

However, once the rigid sleeve 2 has been installed over the pile 1 , it is preferred that lateral movement of the pile 1 within the rigid sleeve is minimized. The longitudinal ribs 18 may serve to minimize the lateral movement of the pile 1 within the rigid sleeve 2. Furthermore, the longitudinal ribs 18 may facilitate installation of the rigid sleeve 2 over the pile 1 with some tolerance to changes in the outer dimensions of the pile 1 . Such changes in the outer dimensions of the pile 1 may result from construction distortion. Other changes in the outer dimensions of the pile 1 may result from temperature variation.

[0041 ] One example cross section shape for the longitudinal ribs 18 is semicircular, as illustrated in FIG. 5B. Other example cross section shapes for the longitudinal ribs 18 include rectangular, triangular, oval and irregular shapes. [0042] Materials for the longitudinal ribs 18 may be selected from the table portions 70A, 70B illustrated in FIGS. 6A and 6B.

[0043] For aspects of the present application, no pre-drilled hole in the soil 12 is required.

[0044] The composite sleeve system is preferably assembled with the pile 1 prior to the installation, together with the optional driving shoe and top lock if needed. Then the pile and the composite sleeve system may be torqued into the soil 12.

[0045] The driving shoe 6 may be seen to minimize the soil resistance and ease the installation of the composite sleeve system consisting of the casing 20 and the rigid sleeve 2. At the top 9 of the rigid sleeve 2, the top lock 3 may be used to hold the sleeve 2 in position during installation and during service life. Of course, if foundation structure is positioned proximate to the top 9 of the rigid sleeve 2 and the foundation structure is judged as sufficiently strong to resist the forces associated with the adfreeze uplift load, the foundation structure can be used to lock the top 9 of the rigid sleeve 2. In such a case, the top lock 3 may be omitted or serve as a temporary tool only for installation. Similarly, if the composite sleeve system is to extend to a helix bottom in case the pile 1 is a helical pile, the helix bottom can be used to lock the bottom 10 of the rigid sleeve 2. In such a case, any bottom lock may be omitted.

[0046] The above-described implementations of the present application are intended to be examples only. Alterations, modifications and variations may be effected to the particular implementations by those skilled in the art without departing from the scope of the application, which is defined by the claims appended hereto.

Claims

WHAT IS CLAIMED IS:

1 . A composite sleeve system comprising: a rigid sleeve covering an outside perimeter of a pile; and a protection casing covering an outside perimeter of the rigid sleeve.

2. The composite sleeve system of claim 1 wherein the rigid sleeve is sized to extend from a ground level down to below a frost depth.

3. The composite sleeve system of claim 1 further comprising a top lock adapted to hold the rigid sleeve from jacking up and damaging a pile cap.

4. The composite sleeve system of claim 1 wherein the rigid sleeve is formed of a material selected to have a low-friction outer surface.

5. The composite sleeve system of claim 1 wherein the casing is formed of a material selected to have a low-friction outer surface.

6. An installation system for a pile, the installation system comprising: a driving shoe fastened to the pile and the driving shoe is oversized to the outer dimension of the pile.

7. The installation system of claim 6 wherein the driving shoe comprises a steel plate.

8. The installation system of claim 7 further comprising a driving panel mounted to the driving shoe.

9. The installation system of claim 8 wherein the driving panel has a triangular shape.

10. The installation system of claim 9 wherein the driving panel has a rectangular shape.