AU2010219374B1 - A Method of Supporting a Building or Other Structure - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION A Method of Supporting a Building or other Structure The following statement is a full description of this invention, including the best method of performing it known to me: 1 Title: A Method of Supporting a Building or other Structure Field of Invention The present invention relates to the field of building construction and repair. 5 Specifically the present invention relates to extending support for a building or other structure to stable strata present beneath the building or other structure. Background Buildings such as houses, office buildings, sheds, factories and other built 10 structures such as walls and the like are seated on footings. The function of footings is to transfer the load of the building to the earth. In certain circumstances existing or proposed footings are not adequate to support the building. This could be because the footing was not made strong or stable enough in the first place, soil tests at the planning stage were inaccurate and 15 resulted in an inappropriate footing being planned or built, the use or structure of the building has changed requiring stronger footings or renovation of the building or other activities requires excavation of the soil on which the existing footing is seated. 20 Various means are currently available to repair, strengthen or underpin footings. These include the use of Franki piles and screw piles. Franki piles are constructed by driving a large sleeve into the earth, filling the sleeve with concrete then removing the sleeve which leaves a concrete pile used to support the building. Screw piles consist of a giant self tapping screw which is inserted 25 into the earth using or using rotary hydraulics. The screw may be from 1.5 to 30 m in length. It can be seen from the above that large and expensive machinery is used in repairing or strengthening footings. In addition, in many cases buildings which 30 require repair or strengthening of their footings are situated in confined situations providing limited or no access for large machinery. Other proposals for supporting buildings and the like such as GB 1418164, U.S. 2004/0105727, GB 2299360, GB 2391052, U.S. 3326006 and GB 2150612 have 35 been put forward in this and other fields, however for various reasons they do not provide satisfactory systems. An aim of the present invention is to address at least some of the difficulties associated with existing methods of repair, strengthening or underpinning of 40 footings of existing and proposed buildings and other structures. The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. 2 Summary In one aspect the invention provides a method of strengthening and/or stabilizing a building or other structure where there is a stable substrate located below the 5 building or other structure by providing additional support which connects said building and/or a footing thereof, or other structure and/or a footing thereof with said stable substrate, wherein said additional support is composed of joined segments of suitable elongate material of which segments are shorter in length than the length of the additional support required to connect said building and/or 10 footing or other structure and/or footing with the stable substrate. The term "footing" used herein refers to concrete, rubble or other material used to seat the building on the foundation. The term "foundation" refers to the soil or other material where the building or other structure is situated. 15 The term "strengthening and/or stabilizing a footing" refers to the act of making the existing or proposed footing more effective in transferring the load of the building or other structure to the foundation and includes underpinning. 20 The term "building or other structure" refers to a built structure such as a house, shed, factory, wall and includes any built structure displaying signs of unacceptable distress or likely to display signs of such distress due to footing movement. The invention covers existing buildings and other structures as well as new buildings and new other structures. 25 The term "stable substrate" refers to stable bedrock, sands, gravels or a combination, which exist (at depth) beneath the building or proposed building site. 30 The term "additional support" refers to extra or improved support for the building beyond the minimum provided by the existing or proposed footing or part thereof. The term "connects said building and/or footing or other structure and/or footing with said stable substrate" refers to a physical connection between the building or 35 other structure and/or its footing and the stable substrate. Usually in the method of the invention it is the footing itself that is connected to the stable substrate however in some cases the footing is too weak and the connection needs to be made between the building itself, such as via the buried block work of the building, and the stable substrate below. 40 The term "joined segments of suitable elongate material" refers to joined pieces of elongate material. The term "elongate" refers to which material is longer than it is wide such as bar or tubular material. Preferably the bar is metal bar or metal tubing, or at least having a tubular portion at one end thereof. More preferably the 45 bar is steel reinforced bar or "Reid bar" or similar or is 'medium gal tubing'. This may is available in various internal diameters, commonly in 6.5m lengths. 3 Preferably the steel is galvanized steel. Alternatively preferably the steel may be coated in zinc after installation such as by painting with zinc rich epoxy paint. The term "the length of the additional support required to connect said building 5 and/or footing or other structure and/or footing with the stable substrate" refers to the distance required to make connection between the building and/or footing and the stable substrate or the distance required to make the connection between the other structure and/or footing and the stable substrate. 10 Preferably the elongate members are joined by swaging an end of one member onto the end of another member. Although this may be achieved by use of a joiner, such as a sleeve or pin the method also contemplates elongate members which have an enlarged diameter tubular portion at one end and a solid portion at the other end so that the enlarged portion of one elongate member is suitable for 15 swaging onto the solid portion of another elongate member. In another aspect the invention provides an improved method of strengthening and/or stabilizing a building or other structure where there is a stable substrate located at a depth below the building or other structure by providing additional 20 support which connects said building and/or a footing thereof or other structure and/or a footing thereof with said stable substrate, wherein said additional support comprises a series of aligned elongate members joined end to end, the improvement comprising where the elongate members are joined by swaging the ends thereof to a joiner member wherein one of said elongate member or 25 joiner member comprises a compressible portion and the other of said elongate or joiner member comprises an incompressible portion in a process comprising partly driving a first elongate member into a substrate adjacent the building; aligning and joining said first member and another elongate member by swaging ends of said elongate members to said joiner member; partly driving the another 30 elongate member into the substrate; and repeating with subsequent other elongate members to provide a series spanning the required depth; and joining an end of a last elongate member in the series to the building and/or footing or joining an end of the last elongate member in the series to the other structure and/or footing. 35 The term "a series of aligned" refers to at least two elongate members arranged end to end in a line. The term "elongate members" refers to members which are longer than they are 40 wide such as pieces of reinforced bar or Reid bar or metal tubing. The term "driving" refers to forcing the member into the ground by hammering or the like. This can be achieved by hand or more preferably by a hydraulic driver which is handheld or attached to machinery such as an excavator. Preferably the 45 members are driven vertically into the substrate. The term "vertically" refers to 4 substantially vertically in relation to the horizontal plane of the building or other structure. The term "adjacent" means directly underneath, next to or nearby the building. 5 Depending on the situation this may be directly next to the building or offset therefrom and includes both inside and outside the building envelope. The term "swaging" refers to clamping, compressing or otherwise deforming a relatively compressible material onto relatively incompressible material. Swaging 10 of the two elongate members is preferably performed by a swaging tool. The term "joiner member" refers to a member suitable for joining the ends of the elongate members. Preferably the ends of the elongate members have a suitable recess or tubular portion, which recess is relatively compressible. Preferably the 15 ends are swaged over a dowel rod partly inserted in the recess/tubular portion or alternatively a relatively compressible sleeve is placed over rigid ends of the elongate members and swaged. The term "a relatively compressible material" refers to a sleeve or tubing of 20 suitable material to allow compression or deformation by swaging onto the relatively incompressible material but is of suitable strength to retain its form during the vertical driving process of hammering into the ground. The relatively compressible material may be on the end of the elongate member. Alternatively the relatively compressible material comprises a separate sleeve and is swaged 25 onto an elongate member where the elongate member is in the form of a rod. It should be appreciated that only the ends of the elongate members need to be a sleeve or a rod although in practice the entire length of the elongate member is conveniently made of a single material. When an incompressible dowel rod is employed it is of appropriate diameter to fit into an end of the elongate member 30 so that the dowel rod and the elongate member may be securely connected. Similarly when a separate sleeve is used it has a suitable internal diameter to fit over an end of the elongate member. The term "joining an end of a last elongate member in the series to the building 35 and/or footing..." refers to making a physical connection between these elements. This typically comprises drilled and grouted reinforcing bars installed in the horizontal plane into the concrete footing then intersecting the vertical bars with said grouted bars via welding before encasing the connection in appropriately sized concrete encasement. In the case of badly deteriorated 40 footings the drilled and grouted reinforcing bars will be placed on the block work or other suitable part of the building or other structure instead of the footing. In another aspect the invention provides improved method of strengthening and/or stabilizing a building or other structure where there is a stable substrate 45 located at a depth below the building or other structure by providing additional support which connects said building and/or a footing thereof or other structure 5 and/or a footing thereof to said stable substrate, wherein said additional support comprises a series of aligned elongate members joined end to end, the improvement comprising a process of partly driving a first elongate member into a substrate adjacent the building; aligning and joining said first member and 5 another elongate member by swaging a suitable sleeve to ends of said members; partly driving the another elongate member into the ground; and repeating with subsequent other elongate members to provide a series spanning the required depth; and joining an end of a last elongate member in the series to the building and/or footing or joining an end of the last elongate member in the series to the 10 other structure and/or footing. The term "a suitable sleeve" refers to a sleeve or tube of appropriate dimensions including internal diameter and of appropriate material so that a part of the sleeve can be slidingly engaged with an end of the member then swaged and the other 15 part can be similarly engaged and swaged onto an end of another member. In yet another aspect the invention provides an improved method of strengthening and/or stabilizing a footing of a building or other structure where there is a stable substrate located at a depth below the footing by providing a 20 series of aligned elongate members joined end to end which series is of sufficient length and connects said building or other structure with said stable substrate, said series having at least a first member and a last member, wherein said first member has a first and second end, which first end contacts with said stable substrate and said last member has a first and second end wherein said second 25 end is secured to the building and/or a footing thereof, the improvement comprising: a) partly driving said first member into a substrate adjacent the building, and b) joining an additional elongate member or last member to said first member by swaging part of a joiner member to an end of said additional or last member and 30 swaging another part of said joiner member to said second end of said first member, c) partly driving the additional or last member into the substrate; optionally d) joining additional elongate members in the same manner to produce sufficient length, and 35 e) securing said last member to the building or footing. In yet another aspect the invention provides an improved method of strengthening and/or stabilizing a footing of a building or other structure where there is a stable substrate located at a depth below the footing by providing a 40 series of aligned elongate members joined end to end which series connects said building or other structure with said stable substrate, said series having at least a first member and a last member, wherein said first member has a first and second end, which first end contacts with said stable substrate and said last member has a first and second end wherein said second end is secured to the 45 building and/or a footing thereof, the improvement comprising: a) partly driving said first member into a substrate adjacent the building, and 6 b) joining an additional elongate member or last member to said first member by swaging part of a sleeve to an end of said additional or last member and swaging the other part of said sleeve to said second end of said first member, c) partly driving the additional or last member into the substrate; optionally d) 5 joining additional elongate members in the same manner to produce sufficient length, and e) securing said last member to the building or footing. 10 Detailed Description of Illustrative Embodiments of the Invention The invention will now be described with reference to the following non limiting illustrative drawings. Figure 1 shows a schematic representation of the elongate members and sleeves 15 used in the invention. Figures 2a and b show a schematic representation of the bars and the complete system in an installed state. 20 Figure 3a shows some applications of the invention and the connection method to failed or failing structures. Figure 3b shows an embodiment of the invention where a dowel rod is used to join the elongate members. 25 Figure 4 shows a sectional elevation of the house, footing and substrate. The figures illustrate the method of the invention used on a house however it will be appreciated that other structures such as sheds, walls and the like come 30 within the scope of the invention. Typically house 192 seated on footing 198 is situated on unstable substrate 130. Located below unstable substrate 130 is stable substrate 140. The basic structural elements used in the method of the invention are the elongate material 35 or elongate members in the form of bar 10 and joiner members in the form of sleeves 30. Reinforcing bar 10 may be 16, 20, 24, 28, 32 or 36 mm in diameter. Sleeve 30 is in the form of 175 mm long tube of appropriate internal diameter to suit the diameter of the bar. This means that the nominal bore of the sleeve may be 2 to 4 mm larger than the diameter of bar 10. Sleeve 30 is advantageously 40 made of galvanized steel which acts as a corrosion protection for the bar due to in-place cathodic metal sacrificial process. Alternatively the elongate material or elongate member may be in the form of compressible tube 15 and joiner member in the form of incompressible dowel rod 45 35 as shown in Figure 3b. 7 Figure 1 shows additional support 50 comprised of first bar 60, intermediate bar 70 and last bar 80. First bar 60 has first end 61 and second end 62. Similarly intermediate bar 70 has first end 71 and second end 72. First bar 60 and intermediate bar 70 are joined at their respective second and first ends 62 and 71 5 by sleeve 30. Similarly, bar 80 has first end 81 and second and 82 and is joined to second end 72 of intermediate bar 70 at first end 81 via sleeve 30. Additional support 50 is driven into the ground until first end 61 contacts stable substrate 140. Last bar 80 can be joined to the building or footing via second end 82. An advantage of using the alternative embodiment utilizing compressible tube 15 10 and dowel rod 35 is that the outside diameter of additional support 50 is consistent all the way along its length so that the soil provides uniform support. The method of the invention is shown schematically in Figures 2a and 2b where additional support 50 comprises an aligned series of four bars 24-1 to 24-4. It will 15 be appreciated that as many bars as necessary may be used. The method of the invention is performed by driving first end 61 of bar 24 -1 partly into the ground adjacent building. Placement of the first bar determines the tracking/alignment of the subsequent bars. It will be seen from Figure 3a that additional support 50 may be substantially vertical or at an angle to vertical. First end 61 may be 20 modified by sharpening or other treatment to improve the penetration. Before second bar 24 -2 is added, sleeve 17 -1 is slipped approximately halfway onto the end first end 71 of second bar 24 -2 and swaged by an appropriate means such as a hydraulic swaging tool. Preferably several swaging operations are carried out on the sleeve by rotating the swaging tool such that the crimped areas 25 are offset from each other to ensure good engagement. Second bar 24 -2 is joined to second end 62 of first bar 24-1 by swaging the other half of sleeve 17 1. In practice, sleeve 17 -1 could be swaged to second end 62 of first bar 24-1 which has been partly driven in to the ground and then second bar 24 -2 added and swaged in situ. Bar 24-3 and sleeve 17-2 are similarly added. 30 The above process is repeated until refusal. This means that the series of bars cannot be physically driven further into the ground and that the first end 61 of first bar 60 has contacted the stable substrate 140. Then last bar 24-4 is added by swaging a first end 91 and connected to the building by its free end namely 35 second end 92. Typically this is achieved with a new footing 24 cast against existing starter bars 24. Starter bars 24 are grouted into holes in footing 198 using HIT150 Hilti grout or similar and are disposed substantially in a horizontal plane. 40 Preferably each of the driven bars is friction cut to avoid to the type of tip "hooking" deformation which occurs when bars are guillotined. It can be seen with the above method that the invention provides a continuous support in a direct line from the building to the stable substrate located beneath. 45 8 This swaging process allows short lengths of bar to be used where overhead clearance is a tight. In addition the method avoids the need for heavy, cumbersome and expensive machinery. The method also allows additional support to be installed in a tight grid fashion through the edge of an existing 5 footing as shown at the left-hand side of Figure 3a and for the additional support to be installed via a new offset footing. Further the invention provides an adaptable system for different load impositions, and depth by varying the number, spacing and diameter of the bars used. More 10 than one additional support can be installed to share the load in heavy structures. Further the method allows rapid installation of deeper footings with very low disturbance to the existing gardens or structures. In addition the process allows for a load testing aspect by only terminating the process when a load-bearing strata, or stable substrate, is reached providing the ability for direct connection to 15 sound substrate or permanent support. Further the overall length of bar installed for each set allows a comparison with other sets and provides an indication of a rock depth, consistent or otherwise. The depth potential is only limited by ground strength and hammer power used. In practice it has been found with use of the present invention that the additional weight of the bars as they are added closely 20 balances the resistance due to sliding friction of the sleeves with the soil, thereby the energy transmitted to the tip at depth is not significantly diminished (depths exceeding 20 metres are easily achieved). The method allows passage through rock layers and extends through weathered material to reach firm strata. Further it allows a consistent bearing set on corresponding foundation (rather than to a 25 nominal depth which is common practice) by continuing to drive the sets until the same firmness of strata is reached. Specifically, some underpinning practices involve digging down to a nominal depth - 1.5m - then filling with concrete. Often the founding material is the same or worse than the footings originally bore on so these offer no real benefit. In contrast the swage-bar system allows an operator 30 to continue down until a sound, reliable base is reached - one end of the house could be 2m down, the other 6m - either way the support is consistent and not dependent on the digging depth of available equipment as is currently the case. Still further the rock profile can be mapped by the length of the bars which allows for anomalous geological features where weak or characteristic bands of material 35 in the soil profile can be detected by installation of the bars. This may assist in determining the cause of footing failure or settlement and help with future management of other areas of the structure such as the need for cut-off drains and the like. 40 When the method of the invention is used in relation to a new building the process is essentially the same as described above except there is the added convenience of being able to drive the bars vertically into the base of the new trenches for the strip, waffle pod or slab footing thickenings. Depending on the weight of the proposed structure, the bars can be driven in rows of 2-4 across the 45 footing (normally 500mm wide) then duplicated at 1-3m spacings and at corners or junctions. This alternative is particularly useful for builders who intend to use 9 delicate or brittle finishes on a potentially unstable site and who wish to avoid any future settlement cracking. Throughout this specification and the claims that follow, unless the context 5 requires otherwise the words "comprise", "comprises", "comprising" will be understood to mean the inclusion of the stated integer, step or group of integers or steps but not the exclusion of any of other integer, step or group of integers or steps. 10

Claims (17)

1. An improved method of strengthening and/or stabilizing a building or other 5 structure where there is a stable substrate located at a depth below the building or other structure by providing additional support which connects said building and/or a footing thereof or other structure and/or a footing thereof with said stable substrate, wherein said additional support comprises a series of aligned elongate members joined end to end, the improvement comprising where the elongate 10 members are joined by waging the ends thereof to a joiner member wherein one of said elongate member or joiner member comprises a compressible portion and the other of said elongate or joiner member comprises an incompressible portion in a process comprising partly driving a first elongate member into a substrate adjacent the building; aligning and joining said first member and another elongate 15 member by swaging ends of said elongate members to said joiner member; partly driving the another elongate member into the ground; and repeating with subsequent other elongate members to provide a series spanning the required depth; and joining an end of the last elongate member in the series to the building and/or footing or joining an end of the last elongate member in the series 20 to the other structure and/or footing.

2. An improved method of strengthening and/or stabilizing a footing of a building or other structure where there is a stable substrate located at a depth below the footing by providing a series of aligned elongate members joined end to end 25 which series connects said building or other structure with said stable substrate, said series having at least a first member and a last member, wherein said first member has a first and second end, which first end contacts with said stable substrate and said last member has a first and second end wherein said second end is secured to the building and/or a footing thereof, the improvement 30 comprising: a) partly driving said first member into a substrate adjacent the building, and b) joining an additional elongate member or last member to said first member by swaging part of a joiner member to an end of said additional or last member and swaging the other part of said joiner member to said second end of said first 35 member, c) partly driving the additional or last member into the substrate; optionally d) joining additional elongate members in the same manner to produce sufficient length, and e) securing said last member to the building, other structure or footing. 40

3. The method of claim 1 or claim 2 wherein the elongate material or elongate member is a bar or tube.

4. The method of claim 3 wherein the bar or tube is metal. 45 11

5. The method of claim 1 wherein said joined segments are joined by a joiner member.

6. The method of any one of claims 1 to 5 wherein said joiner member is a dowel 5 rod or a sleeve of appropriate diameter.

7. The method of claim 6 wherein the joiner member is metal.

8. The method of claim 7 wherein the bar, tube or joiner member is galvanized 10 steel or zinc treated steel.

9. The method of any one of claims 1 to 8 wherein the footing for is an existing building or existing other structure. 15

10. The method of any one of claims 1 to 8 wherein the footing is for a now building or new other structure.

11. An elongate member when used in any one of the methods of claims 1 to 10. 20

12 The elongate member of claim 11 which comprises a bar.

13. The elongate member of claim 11 which comprises a tube.

14. A joiner member when used in any one of the methods of claims 1 to 10. 25

15. The joiner member of claim 14 which comprises a sleeve.

16. The joiner member of claim 14 which comprises a dowel rod or pin. 30

17. The method of any one of claims 1 to 10 substantially as hereinbefore described with reference to the drawings. Dated this 5 th day of April 2011 35 Michael Phillip Sylvester O'Halloran By his Patent Attorneys: Tasmanian Patent Services 12