WO2016095021A1

WO2016095021A1 - Extendable sleeve for piles

Info

Publication number: WO2016095021A1
Application number: PCT/CA2015/051170
Authority: WO
Inventors: Guangfeng QU; Sean HINCHBERGER; Rob Lydan
Original assignee: Hatch Ltd.
Priority date: 2014-12-19
Filing date: 2015-11-12
Publication date: 2016-06-23

Abstract

An extendable sleeve system, covering the outside perimeter of a pile, may assist in prevention of the development of adfreeze bonding between frozen soil and the pile and, consequently, may assist in reduction of the adfreeze uplift load to the pile. When soil becomes frozen and heaves, the sleeve may responsively extend/stretch upward together with the adjacent soil while the pile remains its original position. Thus, the uplift load may be reduced from a direct bonding grip strength between the soil and the pile to an interface friction between the sleeve and the pile.

Description

EXTENDABLE 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, the contents of which are incorporated herein by reference.

FI ELD

[0002] The present application relates generally to piles and, more specifically, to an extendable sleeve for piles.

BACKGROUND

[0003] A pile may be defined as a steel pipe post or heavy H-beam driven vertically into the bed of a soft/firm ground, a river, etc., 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] The present application details an extendable sleeve system for piles. More specifically, aspects of the present application may find use for reducing the effect of adfreeze uplift load for piles in cold regions where foundation soil is frost- suspicious. [0006] According to an aspect of the present disclosure, there is provided a sleeve system. The sleeve system includes extendable sleeve(s) 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 A illustrates a pile and sleeve system, in a partial, vertical cross- sectional view, after installation in a normal state in accordance with an embodiment of the present application;

[0010] FIG. 1 B illustrates the pile and sleeve system of FIG. 1 A in an operational state in accordance with an embodiment of the present application;

[001 1 ] FIG. 2 illustrates, in a plan, cross-sectional view, the pile and sleeve system of FIG. 1A in accordance with an embodiment of the present application;

[0012] FIG. 3 illustrates an installation configuration for the pile and sleeve system of FIG. 1A including a protection casing, a driving shoe and a temporary casing collar in accordance with an embodiment of the present application;

[0013] FIG. 4 illustrates the installation configuration of FIG. 3 in a partial, vertical, cross-sectional view, with the protection casing left in place after installation in accordance with an embodiment of the present application;

[0014] FIG. 5 illustrates, in a plan, cross-sectional view, the driving shoe of FIG. 3 in accordance with an embodiment of the present application;

[0015] FIG 6A illustrates, in a plan view, a driving shoe in accordance with an embodiment of the present application that is distinct from the embodiment illustrated in FIG. 5; [0016] FIG. 6B illustrates, in a side view, a triangle panel configuration for the driving shoe of FIG. 6A in accordance with an embodiment of the present application;

[0017] FIG. 6C illustrates, in a side view, a rectangle panel configuration for the driving shoe of FIG. 6A in accordance with an embodiment of the present application;

[0018] FIG. 7A illustrates, in a partial, vertical, cross-sectional view, a pile and sleeve system in accordance with an embodiment of the present application that is distinct from the pile and sleeve system of FIG. 1A;

[0019] FIG. 7B illustrates, in a plan, cross-sectional view, the pile and sleeve system of FIG. 7A in accordance with an embodiment of the present application; and

[0020] FIG. 8 illustrates a table of materials suitable for use in the pile and sleeve system of FIGS. 1A and 7A.

DETAILED DESCRI PTION

[0021 ] 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.

[0022] 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.

[0023] 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. [0024] 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.

[0025] 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.

[0026] In general, these referenced solutions may either be considered not to be practical in construction or considered to be too expensive. 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.

[0027] In addition, the configuration wherein anti-freezing liquid is to be injected and sealed into the volume between the sheath and pile may be considered to be very difficult or impractical in construction and introduces risks related to

environmental contamination in the event of leakage of the anti-freeze liquid.

[0028] FIG. 1 A illustrates a pile 1 in soil 12. A sleeve system surrounds the pile 1 , extending from a sleeve top 9 to a sleeve bottom 10. The sleeve system includes an outer sleeve 2 and an inner sleeve 3. The sleeve system also includes a top fastener 4 adapted for securing the outer sleeve 2 and the inner sleeve 3 to the pile at the sleeve top 9. Similarly, the sleeve system includes a bottom fastener 5 adapted for securing the outer sleeve 2 and the inner sleeve 3 to the pile at the sleeve bottom 10.

[0029] The outer sleeve 2 may be water-impervious and have an elastic elongation ratio. The minimum useful elastic elongation ratio may be defined for a given location as a quotient resulting when a maximum annual frost heave measurement is the dividend and a measure of frost depth is the divisor. The elastic elongation ratio may be determined for many temperatures over a range extending, for example, down to -40° Celsius.

[0030] FIG. 8 illustrates a table 800 that lists the materials suitable for use for the outer sleeve 2 and for the inner sleeve 3. The outer sleeve 2 can be the composite materials comprising two or more of these materials in the table 800 in FIG. 8, with or without metal wire reinforcement. The inner sleeve 3 is preferably forms of the same material as the outer sleeve 2. As such, the inner sleeve 3 may serve as a backup system, in addition to its primary objective to reduce the interface friction. Optionally, lubricant or talcum powder may be applied along the pile 1 to further reduce interface friction between the inner sleeve 3 and the pile 1 .

[0031 ] The top fastener 4 and bottom fastener 5 may be implemented as a plastic clamp or a metal clamp. Alternatively, the outer sleeve 2 and the inner sleeve 3 may be adhered to the pile 1 by sealants or other alternative methods.

[0032] Below the sleeve bottom 10, a 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 to facilitate the installation of the outer sleeve 2 and the inner sleeve 3, as shown in FIG. 5. Weld locations 14 are identified in FIGS. 5 and 6A. It should be understood that the outside diameter of the driving shoe 6 should be larger than the outside diameter of the protection casing 1 1 . For the pile 1 driven by rotation installation techniques, the driving shoe 6 may be implemented as a steel plate 16 with driving panels 17 can be used for hard soil condition or for long sleeves, as shown in FIGS. 6A, 6B and 6C. The panel 17 can be triangular (see FIG. 6B) or rectangular (see FIG. 6C).

[0033] The material selected for the protection casing 1 1 material should be a rigid material. Materials fitting the rigidity recommendation include high density polyethylene (HDPE), polyvinyl chloride (PVC), steel and iron.

[0034] In FIG. 3, the pile 1 and sleeve system of FIG. 1 A is augmented for an installation configuration. The installation configuration includes a protection casing 1 1 surrounding the pile 1 and sleeve system of FIG. 1 A and abutting the driving shoe 6. The installation configuration further includes a temporary casing collar 13 installed atop the protection casing 1 1 . [0035] The temporary casing collar 13 at the top of the protection casing 1 1 may be a temporary chain clamp or a collar fastened to, or welded to, the pile 1 .

[0036] In overview, aspects of the present application replace an intrinsic load transferring mechanism of soil-pile interaction from a direct soil-pile bonding to a sleeve-pile interface friction. The direct soil-pile bonding may be considered to involve the soil bonding to an uncontrolled surface. However, when the load transferring mechanism involves sleeve-pile interface friction, it may be considered that the pile interfaces with an engineered surface of the inner sleeve 3. Notably, features of the engineered surface are controllable.

[0037] A friction load between the inner sleeve 3 and the pile 1 may be determined in a straightforward way. Indeed, the interface friction properties between two known materials may be determined through a literature review. Alternatively, the interface friction properties between two known materials may be determined through laboratory testing. As such, it may be shown that, through the use of aspects of the present application, the adfreeze uplift loads on piles may be significantly reduced. Conveniently, the friction stress present when aspects of the present application are in use is much lower than the bond stress present when there is direct bonding between the soil 12 and the pile 1 .

[0038] The application does not to completely eliminate the adfreeze uplift load, but to reduce it to a certain level as the interface friction load so that this uplift load does not govern the design. In another word, this invention does not pursue the zero adfreeze load because the pile will have a certain uplift resistance anyway for other load cases in design which can be used to resist the interface friction load as per the sleeve system.

[0039] The driving shoe 6 may assist the installation the sleeve system during pile driving. Where hard soil is encountered, the protection casing 1 1 may be used to protect the sleeve system during driving of the pile 1 into the soil 12.

[0040] In use and in view of FIG. 1 A, before the pile 1 is driven into the soil 12, the outer sleeve 2 may be secured to the pile 1 in a water-tight manner. At the sleeve top 9, the outer sleeve 2 may be secured to the pile 1 with the top fastener 4. At the sleeve bottom 10, the outer sleeve 2 may be secured to the pile 1 with the bottom fastener 5. Similarly, the inner sleeve 3 may be secured to the pile 1 in a water-tight manner. At the sleeve top 9, the inner sleeve 3 may be secured to the pile 1 with the top fastener 4. At the sleeve bottom 10, the inner sleeve 3 may be secured to the pile 1 with the bottom fastener 5.

[0041 ] The pile 1 may be driven into the soil 12 to such a depth that the sleeve top 9 may be positioned near or slightly higher than a surface 7 of the soil 12, thereby establishing a likelihood that the sleeve system covers the pile 1 during the annual frost heave. Preferably, the coverage of the pile 1 by the sleeve system extends from the surface 7 of the soil 12 to a depth 8 that is representative of a depth of frost within the soil 12.

[0042] Conveniently, according to aspects of the present application, no pre- drilled hole is required to house the pile 1 and sleeve system.

[0043] Installing the pile 1 and sleeve system into the soil 12 may be

accomplished using one of at least two installation methods.

[0044] A first installation method is well suited to situations in which the soil 12 is relatively hard or situations in which the frost depth is relatively deep (defined as being more than 5 ft to 8 ft). The first installation method employs the protection casing 1 1 and the driving shoe 6. As shown in FIG. 3, the protection casing 1 1 abuts the driving shoe 6. Furthermore, the temporary casing collar 13 can be used to hold the protection casing 1 1 in position during the installation of the pile 1 and sleeve system into the soil 12.

[0045] Technically, "relatively hard," in soil mechanics, refers to "blow count is over than 20 or undrained shear strength is higher than 30 kPa", where blow count is a terminology to assess the compactness of soil.

[0046] A driving force may then be applied to the temporary casing collar 13 and to the driving shoe 6 by driving the pile shaft. The driving force on the temporary casing collar 13 is transferred to the protection casing 1 1 The driving shoe is advanced with the pile 1 to ease the installation of the protection casing 1 1 . [0047] The protection casing 1 1 can be removed or left in place after installation. If the protection casing 1 1 is left in place, as illustrated in FIG. 4, the protection casing 1 1 provides additional protection for the outer sleeve 2 over the duration of the design life. The protection casing 1 1 , when left in place, also may reduce normal pressure directly acting on the outer sleeve 2 due to the arch effect. As such, the protection casing 1 1 can be shown to further reduce the interface friction force load being transferred to the pile 1 .

[0048] On the other hand, the design shall account for the potential jack-up condition of the protection casing 1 1 , when left in place. The protection casing 1 1 may be subject to adfreeze uplift and, thereby, may be jacked up against a foundation structure and transfer additional load through direct contact between the protection casing 1 1 and the foundation structure. As such, the protection casing 1 1 may be designed to yield at an allowable stress level, thereby preventing transferring excessive load to the foundation structure. Alternatively, a casing stopper (not shown) may be installed at the top of the protection casing 1 1 to split or cut the protection casing 1 1 when the adfreeze uplift movement exceeds a predetermined limit.

[0049] A second installation method (as shown in FIG. 7A) is well suited to situations in which the soil 12 is relatively soft or situations in which the frost depth is relatively shallow (defined as being less than 5 ft).

[0050] A driving force may then be applied to the driving shoe 6 through the pile shaft. The driving shoe 6 is advanced with the pile 1 to ease the installation of the sleeve system.

[0051 ] If the sleeve system extends to the top of the pile 1 , a driving bolt of a pile installation cap can be used as a mechanical lock to hold the protection casing 1 1 in position during installation.

[0052] In operation, as the soil 12 becomes frozen and starts to heave, the outer sleeve 2 stretches and extends up together with adjacent frozen soil 12. In this manner, an expanded zone above the surface 7 of the soil 12, as shown in Figure 1 B. The upward elongation of the outer sleeve 2 introduces a friction force to the inner sleeve 3 and the pile 1 . As such, the design uplift load for the pile 1 is reduced from the adfreeze bond load between the soil 12 and the outer sleeve 2 to the interface friction between the inner sleeve 3 and the pile 1 .

[0053] Conveniently, by sealing the top 9 of the outer sleeve 2 with the top fastener 4, water and dirt infiltration into the space between the outer sleeve 2 and the inner sleeve 3 may be avoided. Similarly, by sealing the bottom 10 of the outer sleeve 2 with the bottom fastener 5, water and dirt infiltration into the space between the outer sleeve 2 and the inner sleeve 3 may be avoided.

[0054] The uplift load in this invention is governed by the well-understood interface friction between sleeve and pile, independent on soil condition which is always various from site to site.

[0055] The installation for this invention can provide protection to the sleeve system during driving into ground and is in an efficient way to ensure the project delivery schedule.

[0056] It should be noted that no liquid is required to fill the space between the sleeve and the pile, as this configuration is not feasible considering the

constructability and the environmental risk of the anti-freeze liquid.

[0057] Notably, aspects of the sleeve system of the present application may be seen to reduce down-drag for piles in soft clay foundation where soil is expected to have settlement and down-drag load governs, at least partially, the pile design.

[0058] Furthermore, aspects of the sleeve system of the present application may be seen to reduce heave/shrinkage for piles in the regions where foundation soil expected to heave or shrink.

[0059] 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 sleeve system comprising: an outer extendable sleeve covering an outside perimeter of a pile.

2. The sleeve system of claim 1 further comprising an inner sleeve, the inner sleeve positioned such that the outer sleeve covers an outside perimeter of the inner sleeve.

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

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

5. The sleeve system of claim 2 wherein the inner sleeve comprises sleeve materials and the sleeve materials comprise water tight materials.

6. The sleeve system of claim 1 wherein the outer sleeve comprises sleeve materials and the sleeve materials comprise water tight materials.

7. The sleeve system of claim 2 wherein the top and bottom of the sleeves are secured to the pile.

8. The sleeve system of claim 1 wherein, in operation, responsive to frozen soil heaving, the outer sleeve stretches and moves up along with the soil, whereas the pile maintains its position.

9. An installation system for a pile, the installation system comprising: a protection casing sized to fit around the pile.

10. The installation system of claim 8 wherein a driving shoe is fastened to the pile and the driving shoe is oversized to the outer dimension of the protection casing;

1 1 . The installation system of claim 8 wherein a temporary casing collar is adapted for installation atop the protection casing to hold the protection casing in a position during installation of the pile.