WO2008119879A1

WO2008119879A1 - Bedrock foundation

Info

Publication number: WO2008119879A1
Application number: PCT/FI2008/050143
Authority: WO
Inventors: Hannu Jokiniemi; Marko Moisio
Original assignee: Rautaruukki Oyj
Priority date: 2007-03-30
Filing date: 2008-03-28
Publication date: 2008-10-09
Also published as: FI20075214A0; FI20075214L; SE534495C2; NO20093073L; SE0901276L

Abstract

The invention relates to a method for providing a bedrock foundation for a building or structure. In the method, one or more pillars of the building or structure are supported on the foundation in such a manner that the method comprises the steps of breaking a hole into the bedrock for mounting a pile, pouring concrete into the hole up till a predefined height, and mounting the pile in the hole filled with concrete.

Description

BEDROCK FOUNDATION

BACKGROUND OF THE INVENTION

[0001] The invention relates to a method according to the preamble of claim 1 for providing a bedrock foundation, and especially to a method for providing a bedrock foundation for a building or structure, in which method one or more pillars of the building or structure are supported on the foundation. The invention further relates to a method according to the preamble of claim 10 for providing a bedrock foundation, and especially to a method for providing a bedrock foundation for a building or structure, in which method one or more pillars of the building or structure are supported on the foundation. The invention further relates to a bedrock foundation according to the preamble of claim 20, and especially to a bedrock foundation of a building or structure, on which foundation one or more pillars of the building or structure are supported on the foundation.

[0002] According to the prior art, bedrock foundations for buildings or large structures are provided by first exploding bedrock. After this, in the explosion site, a concrete sole is cast and the pillars of the building are supported thereon.

[0003] A problem with the arrangement described above is that explosions often result in poorly controllable explosion craters, whereby too much of the bedrock is often exploded. In addition, it is then necessary to cast a large concrete sole on top of the exploded surface. Due to uncontrollable explosion, the concrete sole often needs to be made very large. Casting the concrete sole requires a significant amount of time and its drying is very slow. Therefore, in a construction project, a lot of time is needed to cast the concrete sole and to wait for it to dry, before it is possible to build on top of the foundation.

BRIEF DESCRIPTION OF THE INVENTION

[0004] It is thus an object of the invention to develop a method for providing a bedrock foundation and a bedrock foundation in such a manner that the above-mentioned problems can be solved. The object of the invention is achieved with the method according to the characterising part of claim 1 , which is characterised by the steps of

- breaking a hole in the bedrock to mount a pile,

- filling the hole with concrete up to a specific height, and - mounting the pile into the hole filled with concrete.

[0005] The object of the invention is also achieved with the method according to the characterising part of claim 10, which is characterised by the steps of

- breaking a hole in the bedrock to mount a pile,

- mounting the pile into the hole, and

- filling the space between the pillar and the hole walls with concrete to lock the pile into the hole.

[0006] The object of the invention is further achieved with a bedrock foundation according to the characterising part of claim 22, which is characterised in that the bedrock foundation comprises a hole broken into the bedrock, a pile mounted in the hole, and a concreting in the hole for locking the pile therein.

[0007] Preferred embodiments of the invention are set forth in the dependent claims.

[0008] The invention is based on replacing the casting of the concrete sole by piling provided in the bedrock. According to the present invention, a hole is first broken into the bedrock. The breaking is preferably done by drilling or by some other corresponding well controllable breaking method. After this, concrete is poured into the hole up till a predefined height. If necessary, the hole can be filled with concrete. After this, a pile, preferably a steel-pipe pile, is pushed into the concrete and the concrete is let dry, whereby the pile locks into the hole. Alternatively, the pile can be set into the hole before filling the hole with concrete. Concrete can then, if wanted, be poured separately inside the pipe-like pile and between the outer surface of the pile and the side walls of the hole. It should be noted that instead of a pile, a pillar of a building or some other load-bearing part of the frame of the building can be directly supported in the hole.

[0009] The method and system of the invention provide the advantage that this type of bedrock foundation is quick to make. In the bedrock foundation of the invention, the amount of concrete used is small in comparison with making a concrete sole, so it dries in a very short time and, consequently, the construction work is significantly faster. In addition, making this type of foundation does not require massive exploding work, which means that it is not necessary to transport a large amount of exploded rock from the construction site. This too brings cost savings and considerably reduces the amount of work and number of work stages.

BRIEF DESCRIPTION OF FIGURES

[0010] The invention will now be described in greater detail by means of preferred embodiments and with reference to the attached Figure 1 which shows a bedrock foundation according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Figure 1 shows a bedrock foundation according to the present invention. According to the invention, a hole 2 is first broken into uncovered or visible bedrock. In this context, the hole 2 refers to a hole, recess or any cavity that extends downward inside bedrock and is arranged to receive a pile. According to Figure 1 the hole 2 is broken into the bedrock 4 by using some known breaking method. The hole 2 is preferably broken by drilling with a rock drill and/or rock drill point, but other breaking methods, such as milling, can also be used. The hole breaking is preferably done using a method that enables controlled breaking in such a manner that the size and shape of the hole is suitable for the required purpose. The hole 2 is broken into the bedrock 4 to a predefined depth from the bedrock surface 16. The hole 2 can be made rectangular, cylindrical or the like in such a manner that the side walls 8 of the hole extend essentially vertically. Alternatively the hole 2 can be made conical in such a manner that its cross-sectional area increases or decreases towards the bottom of the hole, in other words, the side walls 8 extend at an angle to the vertical direction. The depth of the hole may be 1.0 to 2.5 m. However, it should be noted that the present invention is not restricted by the depth of the hole, the depth may vary according to each application.

[0012] According to a first embodiment of the present invention, concrete 6 is poured into the hole 2 made in the bedrock 4. So much concrete 6 is preferably poured into the hole 2 that it fills the hole 2 up to or close to the bedrock surface 16 or to a predefined height from the bottom of the hole 2. After the hole 2 has been filled with concrete 6 or a desired amount of concrete 6 has been poured in it, a pile 10 is mounted in the hole 2. The pile 10 is mounted in the hole 2 by pushing it through the concrete 6 to a desired depth. The mounting of the pile 10 can be done for instance by pushing it downward with a machine. [0013] The pile 10 can be any pile, such as a concrete pile, wood pile, steel pile, or any other corresponding pile suitable for the construction site. In a preferred embodiment, the pile 10 is a steel-pipe pile that is relatively easy to push into the concrete 6 in the hole 2. When the pile 10 is mounted in the hole 2, the concrete 6 is let dry and harden so that the pile 10 fastens firmly into the hole 2. If necessary, the pile 10 can be supported and/or kept in the desired position in the hole 2 so that it remains in the desired position when the concrete dries. This can be done for instance by mounting wedges made of metal, wood or some other suitable material in the gap between the pile and hole. Fastening means for fastening and supporting the pile to the pillar can be provided at the top end of the pile 10. These fastening means may for instance comprise a flange provided or mounted at the top end of the pile 10 and means for providing a bolted joint between the pile and pillar. Other alternative fastening means can also be used, and in some cases, the pillar can also be welded directly to the pillar.

[0014] The bedrock foundation of Figure 1 can also be provided with an alternative second embodiment of the present invention. According to this second embodiment, a hole 2 is provided in the bedrock 4 like in the first embodiment. After the hole 2 has been broken, a pile 10 is mounted in the hole 2 and concrete 6, i.e. grouting, is poured between the outer surface 12 of the pile and the walls 8 of the hole 2 to lock the pile 10 into the hole 2. When using a pipe-like pile 10, such as a steel-pipe pile, concrete can be poured separately also inside the pile 10. In other words, after mounting the pile 10 in the hole, concrete 6 is poured between the outer surface 12 of the pile 10 and the wall 8 of the hole and inside the pile 10 separately.

[0015] Alternatively, in this second embodiment of the method, the pipe-like pile 10 may comprise openings or holes (not shown) close to its end to be mounted in the hole 2, or notches (not shown) at its end to be mounted in the hole 2. In this case, the pouring of concrete into the hole 2 can be done by pouring the concrete 6 only inside the pipe-like pile 10 and it exits the pile through the openings and/or notches to the space between the outer surface 12 of the pile 10 and the walls 8 of the hole 2. Similarly, the concrete 6 can be poured only in the space between the outer surface 12 of the pile 10 and the walls 8 of the hole 2, in which case the concrete pushes through the openings and/or notches in the pile 10 inside the pile 10. By means of the openings and/or notches of the pile 10, it is possible to obtain the same end-result as in the cases presented above.

[0016] The drilling of the hole 2 can also be done directly by a rock drill point installed on the pile 10. The pile is then used as part of the drill. The rock drill point can be left on the pile 10 or it can be removed from it. In a first embodiment of the present method, the pile 10 with the rock drill point is lifted away from the hole 2 after drilling in order to pour concrete 6 into the hole. The rock drill point can then be removed from the drill, if desired, when the pile 10 is out of the hole 2. In a second embodiment of the present invention, in which concrete 6 is only poured in after the pile 10 has been mounted in the hole, the pile 10 need not be lifted from the hole 2 after drilling, but can be left in the hole 2 together with the rock drill point. If desired, the pile 10 can in this case too be lifted out of the hole 2 and the rock drill point removed from the pile 10.

[0017] One or more reinforcements 18 that may be flange-like parts, annular parts or the like can also be provided on the pile 10 to extend outward from the outer surface 12 of the pile 10. The reinforcement 18 may be a reinforcement ring, for instance, welded around the steel-pipe pile. If necessary, there may be two or more reinforcements. The purpose of the reinforcement 18 is to strengthen the pile 10 and fasten the pile 10 better into the concrete 6. It should also be noted that, if necessary, reinforcements can also be provided inside the pipe-like pile in such a manner that they extend inside the inner surface of the pile. The reinforcements 18 are provided at the end of the pile 10 to be mounted into the hole 2 or near it, and there may be several of them at different distances from the end of the pile 10 mounted in the hole 2. In addition, the inside of the pipe-like pile may be equipped with an iron fitting that may be installed inside the pipe before or after the pipe is mounted in the hole.

[0018] If the mounting of the pile 10 in the hole 2 requires it, a separate concrete layer (not shown) may first be poured on the bottom of the hole 2 and let dry before the rest of the concrete 6 is poured in and the pile is mounted in the hole 2. The pile 10 may then be set in the hole 2 in such a manner that its bottom end is supported on this concrete layer on the bottom of the hole 2. The concrete layer at the bottom of the hole can be used to level the bottom of the hole 2, whereby the pile 10 can be set to extend to this concrete layer and support against it.

[0019] One or more tie bars 14 can also be mounted in the hole to extend from the hole 2 into the bedrock 4. The tie bar 14 can be mounted in the bedrock 4 by drilling and/or injecting or in some other known method in such a manner that its top end extends into the hole 2. The tie bar then fastens into the concrete 6 poured in the hole 2. The tie bars 14 are preferably mounted in place after the hole 2 is made and before the concrete 6 is poured and/or the pile 10 is mounted in the hole 2. Any prior-art tie bar can be used as the tie bars 14. The tie bar 14 preferably extends into the concrete 6 and/or a separate concrete layer, if any, at the bottom of the hole 2.

[0020] When using a pile mounted into the hole, the hole and/or pile is dimensioned in such a manner that the top end of the pile, on which the pillar or some other load-bearing part of the building will be supported, extends from the hole to the ground surface or a predefined distance above it. In addition, the diameter of the hole and the pile or pillar mounted therein is arranged in such a manner that there will be no large gap between the outer walls of the pile or pillar and the walls of the hole, just a gap of about 20 to 60 mm, for instance. The diameter of the pile may be in the range of 400 to 800 mm, for example. Further, the connection between the top end of the pile mounted in the hole and the pillar fastened thereto and/or fastening means for fastening and supporting the pi((ar to the pile can be covered with concrete to achieve corrosion protection.

[0021] If on top of the bedrock, there is a significant amount of soft and/or loose earth, a protective pipe can be used in the method, and the pipe is taken into the hole during drilling and extends from the bottom of the hole to the surface of the soft earth layer on the bedrock, thus preventing the soft earth from falling into the hole after drilling and blocking the hole.

[0022] It is obvious to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not restricted to the examples described above, but may vary within the scope of the claims.

Claims

1. A method for providing a bedrock foundation for a building or structure, in which method one or more pillars of the building or structure are supported on the foundation, characterised by the method comprising

- breaking a hole in the bedrock to mount a pile or pillar,

- filling the hole with concrete up to a specific height, and

- mounting the pile or pillar into the hole filled with concrete.

2. A method as claimed in claim 1, characterised in that the breaking of the hole in the bedrock is done by drilling with a rock drill.

3. A method as claimed in claim 1 or 2, characterised in that the breaking of the hole in the bedrock is done by drilling with a rock drill point mounted on the pile.

4. A method as claimed in claim 2 or 3, characterised in that the rock drill and/or pile equipped with a rock point is lifted up from the hole before the hole is filled with concrete.

5. A method as claimed in any one of claims 1 to 4, character- is e d in that the used pile is a steel pipe.

6. A method as claimed in any one of claims 1 to 4, character- is e d in that the used pile has one or more reinforcements at its bottom end that is mounted in the hole.

7. A method as claimed in any one of claims 1 to 6, character- is e d in that one or more tie bars are also mounted into the hole to extend from the hole into the bedrock.

8. A method as claimed in any one of claims 1 to 6, character- is e d in that the hole is made rectangular, cylindrical or in some other corresponding shape in such a manner that the side walls of the hole extend essentially vertically.

9. A method as claimed in any one of claims 1 to 6, character- is e d in that the hole is made conical in such a manner that its cross-sectional area increases or decreases towards the bottom of the hole.

10. A method as claimed in any one of claims 1 to 6, characterised in that a concrete layer is first cast into the bottom of the hole to set the pile on.

11. A method for providing a bedrock foundation for a building or structure, in which method one or more pillars of the building or structure are supported on the foundation, characterised by the method comprising

- breaking a hole in the bedrock to mount a pile or pillar,

- mounting the pile or pillar into the hole, and

- filling the space between the pile or pillar and the hole walls with concrete to lock the pile or pillar into the hole.

12. A method as claimed in claim 11, characterised in that the breaking of the hole in the bedrock is done by drilling with a rock drill.

13. A method as claimed in claim 11 or 12, characterised in that the breaking of the hole in the bedrock is done by drilling with a rock drill point mounted on the pile.

14. A method as claimed in claim 13, characterised in that the pile is left in the hole after the drilling.

15. A method as claimed in any one of claims 11 to 14, character i s e d in that the used pile is a steel pipe.

16. A method as claimed in any one of claims 11 to 14, character i s e d in that the used pile has one or more reinforcements at its bottom end that is mounted in the hole.

17. A method as claimed in any one of claims 11 to 16, character i s e d in that one or more tie bars are also mounted into the hole to extend from the hole into the bedrock.

18. A method as claimed in any one of claims 11 to ^.characterised in that the hole is made rectangular, cylindrical or in some other corresponding shape in such a manner that the side walls of the hole extend essentially vertically.

19. A method as claimed in any one of claims 11 to 17, character i s e d in that the hole is made conical in such a manner that its cross- sectional area increases or decreases towards the bottom of the hole.

20. A method as claimed in any one of claims 11 to 19, character i s e d in that a pipe-like pile is used and concrete is separately poured inside the pile.

21. A method as claimed in any one of claims 11 to 19, character i s e d in that a pipe-like pile is used with one or more openings or notches in or close to its bottom end mounted in the hole, and concrete is poured only inside the pipe-like pile, whereby the concrete also pushes through the one or more openings or notches in the pile into the space between the outer surface of the pile and the walls of the hole.

22. A method as claimed in any one of claims 11 to 19, character i s e d in that a pipe-like pile is used with one or more openings or notches in or close to its bottom end mounted in the hole, and concrete is poured only into the space between the outer surface of the pipe-like pile and the walls of the hole, whereby the concrete also pushes through the one or more openings or notches in the pile inside the pipe-like pile.

23. A method as claimed in any one of claims 11 to 22, c h a r a c - terised in that a concrete layer is first cast at the bottom of the hole to mount the pile on.

24. A bedrock foundation of a building or structure on which one or more pillars of the building or structure are supported, characterised in that the bedrock foundation comprises a hole broken into the bedrock, a pile or pillar mounted in the hole, and concrete poured into the hole to lock the pile or pillar into it.

25. A bedrock foundation as claimed in claim 24, characterised in that it also comprises one or more tie bars mounted to extend from the bedrock into the concrete in the hole.

26. A bedrock foundation as claimed in claim 24 or 25, characterised in that the pile is steel pipe.

27. A bedrock foundation as claimed in any one of claims 24 to 26, characterised in that the pile has at its bottom end mounted in the hole one or more reinforcements that extend outwards from the outer surface of the pile.

28. A bedrock foundation as claimed in any one of claims 24 to 27, characterised in that at or close to its bottom end mounted in the hole the pile comprises one or more openings or notches through which the concrete extends.

29. A bedrock foundation as claimed in any one of claims 24 to 28, characterised in that the hole is made by drilling.

30. A bedrock foundation as claimed in any one of claims 24 to 29, characterised in that the hole is cylindrical or rectangular in shape in such a manner that its side walls extend essentially vertically.

31. A bedrock foundation as claimed in any one of claims 24 to 29, characterised in that the hole is conical in such a manner that its cross- sectional area increases or decreases towards the bottom of the hole.

32. A bedrock foundation as claimed in any one of claims 24 to 31 , characterised in that the pile comprises a rock drill point at its bottom end mounted in the hole.

33. A bedrock foundation as claimed in any one of claims 24 to 32, characterised in that the foundation also comprises a concrete layer provided at the bottom of the hole and the pile is mounted on it.