Pile for strengthening building foundations

Abstract

 A modular strengthening pile for the foundations of buildings comprises a stainless steel outer jacket (2) which has, transversally to the main direction of extension (X) of the pile, a dimension of between 3 and 15 cm, and a thickness of between 0.8 and 5 mm; a core (3) inside the jacket (2) and at least partly consisting of an inert material (4); and engagement means (5) attached to at least a first end (2a) of the jacket (2), allowing connection to a second end (2b) of the jacket of another pile (1) .

Description

[0001] The present invention relates to a pile for strengthening building foundations.

[0002] It is known that buildings comprise buried foundations on which the construction forming the portion of the building above the surface of the ground is erected.

[0003] The foundations are designed to support the portion of the building above the surface of the ground and keep it in a predetermined position.

[0004] Therefore, during the design and construction of any building, much attention is paid to the sizing and positioning of the foundations.

[0005] The sizing and positioning of the foundations depends on the type of building to be erected and the type of ground on which the building will be built.

[0006] Obviously, the softer the ground, the greater the dimensions and depth of the foundations will have to be.

[0007] In any event, it is always possible to design and produce suitable foundations according to the building to be erected.

[0008] Moreover, during the operating life of the building, the design conditions, relative to which the foundations were designed and produced, may change.

[0009] These changes relative to the design conditions may be due to many factors, for example earthquakes, landslides, rising or lowering water table, or other natural events.

[0010] Such design conditions may also vary following modifications to the portion of the building above the surface of the ground, for example after extension work or the like.

[0011] In all of these cases work is required to restore the correct functionality of the foundations. Such work may also be done when the building is erected. Other types of work involve the use of piles for strengthening building foundations, able to help the foundations to support the building.

[0012] A first type of prior art pile for strengthening building foundations consists of a hollow cylinder with a plurality of radial holes which is inserted in a hole which has the shape of a vertical shaft, made through the foundations and extending underneath them by a predetermined depth (normally calculated in such a way as to reach the more solid layers of the ground). Once the pile has been inserted in the hole, the hollow cylinder is filled with cement which, coming out of the radial holes, fills both the pile and the hole and stably anchors the pile to the ground. Connecting the pile to the foundations helps the latter to support the building.

[0013] However, this type of pile for strengthening building foundations has the disadvantage of requiring the preparation of a hole for its installation.

[0014] The costs involved in making said hole, normally obtained by drilling the ground, are often very high, making installation of the pile for strengthening building foundations just described relatively expensive.

[0015] Moreover, this type of pile for strengthening building foundations does not allow a guarantee to be provided in advance of a predetermined resistance to the load to be supported, since the maximum load which can effectively be reached by the pile before it gives way and sinks into the ground can only be established after installation or using estimate calculations which have a significant margin of error.

[0016] In other words, to establish the effective maximum load which the pile can support, the pile must be tested after it has been installed. However, at that point any further change (increase) in the maximum load value which can be supported is no longer possible.

[0017] In addition, the pile is not easy to handle, since it often consists of a single, very long element.

[0018] A known pile for strengthening building foundations, which at least partly overcomes the above-mentioned disadvantages, consists of a suitably sized iron bar, which is driven into the ground through a hole made in the foundations then connected to the foundations.

[0019] The depth to which the bar is pushed into the ground depends on the load which must be supported. Measuring the force necessary to make the bar penetrate the ground, it is possible to establish the load that the bar can support without it sinking any further, and therefore interrupting bar driving when the required resistance to penetration value is reached guarantees that the load will be supported.

[0020] However, since the ground is normally very moist, often also containing many mineral salts, the iron bar is subject to a high level of corrosion which compromises its mechanical properties relatively rapidly.

[0021] Moreover, this type of prior art pile for strengthening building foundations is also heavy and expensive to make, since a bar made completely of iron must be produced.

[0022] It is also, again, difficult to handle.

[0023] In this context, the main technical purpose of the present invention is to propose a pile for strengthening building foundations which is free of the above-mentioned disadvantages.

[0024] In particular, the aim of the present invention is to provide a pile for strengthening building foundations which resists corrosion.

[0025] Another aim of the present invention is to propose a pile for strengthening building foundations which is able to support a predetermined load.

[0026] Yet another aim of the present invention is to provide a pile for strengthening building foundations with reasonable production costs.

[0027] A further aim of the present invention is to propose a pile for strengthening building foundations which is easy to handle.

[0028] The technical purpose indicated and the aims specified are substantially achieved by a pile for strengthening building foundations comprising the technical features described in one or more of the claims herein.

[0029] Further features and advantages of the present invention are more apparent in the description below, with reference to a preferred, non-limiting, embodiment of a pile for strengthening building foundations, illustrated in the accompanying drawings, in which:

• Figure 1 is a perspective view of a pile for strengthening building foundations in accordance with the present invention; and
• Figure 2 is a cross-section according to plane II - II of the pile illustrated in Figure 1.

[0030] With reference to the accompanying drawings, the numeral 1 denotes as a whole a pile for strengthening building foundations in accordance with the present invention.

[0031] The pile 1 comprises an outer jacket 2 and a core 3 located inside the jacket 2 and connected to it (in the embodiment illustrated the connection consists of the bond between the core 3 and the jacket 2).

[0032] The outer jacket 2, in the preferred embodiment illustrated, is a tube with a circular cross-section and has a main direction of extension X.

[0033] However, the outer jacket 2 may have the shape of any hollow straight prism with a polygonal base.

[0034] The diameter of the outer jacket 2, that is to say the dimension transversal to the main direction of extension X, is between 3 and 15 cm, preferably between 4 and 10 cm, and more preferably less than 8 cm.

[0035] It must be emphasised that the term diameter is used in this context to indicate the diameter of a circle having the same area as the polygon forming the transversal area of the jacket 2.

[0036] If the jacket 2 has the shape of a tube with a circular base, as in the embodiment illustrated in the accompanying drawings, the equivalent diameter therefore coincides with the effective diameter of the circle forming the base of the jacket 2.

[0037] The core 3 of the pile 1 at least partly consists of an inert material 4.

[0038] In the preferred embodiment, the inert material 4 consists of a cement-based mix, that is to say building material consisting of a mixture of mortar and rough stones or pieces of broken stone.

[0039] In particular, the cement-based mix may be concrete, that is to say consisting of a mixture of a hydraulic binder, for example cement, or air binder, for example lime, aggregates, for example sand and gravel, and water.

[0040] The particle size distribution of the aggregates is low, to guarantee even distribution of the aggregates in the core of the pile 1 and the concrete may be enriched with hardening additives to help it to set in the pile 1 before installation (described in detail below).

[0041] The core may also be strengthened with metal elements such as iron rods (for example giving reinforced concrete).

[0042] In an alternative embodiment, the inert material 4 may also comprise one or more synthetic components (such as resins) acting as binders or constituting the entire core.

[0043] Advantageously, the jacket 2 is made of stainless steel and is between 0.8 and 5 mm thick, preferably between 1 and 3 mm thick, or more preferably 1.5 mm thick.

[0044] In this way, it is guaranteed that the pile 1 is not subject to oxidation, even in the presence of high levels of moisture and mineral salts.

[0045] Moreover, the reduced thickness of the jacket guarantees not just the required strength, but also a reasonable pile 1 weight and very reasonable production costs.

[0046] Moreover, advantageously, the pile 1 comprises engagement means 5 attached to at least a first end 2a of the jacket 2 to allow connection of two consecutive piles, thus making the pile a modular element.

[0047] In the embodiment illustrated, the engagement means 5 are also attached to a second end 2b of the jacket 2 opposite the first end 2a, whilst there remains a central portion 2c of jacket 2 without engagement means 5.

[0048] In the preferred embodiments, the engagement means 5 comprise a sleeve 6 attached to the second end 2b of the jacket 2, and such that its can receive the first end 2a of another pile 1 and connect with it. In the preferred embodiment illustrated the sleeve 6 forms one part with the jacket 2 and consists of the second end 2b of the jacket 2 and the portion of jacket 2 adjacent to it. The sleeve 6 is an ideal extension of the jacket 2, that is to say it has the same transversal dimensions and the same thicknesses as the central portion 2c of the jacket 2.

[0049] In this way, advantageously, the sleeve 6 may be engaged by a tapered portion 7 of the jacket 2 of another pile 1 located at the first end 2a of the jacket 2 and contributing to formation of the engagement means 5.

[0050] In particular, said tapered portion 7 comprises a first zone 8 with a dimension transversal to the main direction of extension X of the jacket 2 which is less than the transversal dimension of the central portion 2c of the jacket 2.

[0051] In the preferred embodiment, the transversal dimension of the first zone 8 of the tapered portion 7 is equal to the difference between the transversal dimension of the central portion 2c of the jacket 2 and twice the thickness of the jacket 2 (in other words the tapered portion 7 and the sleeve 6 are shaped to fit one another).

[0052] In this way, the first zone 8 is the correct size for insertion in the sleeve 6 of another pile 1 since, as already indicated, the transversal dimensions and thicknesses of the sleeve 6 are identical to those of the central portion 2c of the jacket 2.

[0053] The tapered portion 7 also comprises a second connecting zone 9 (for example having the shape of an arc) which connects the first zone 8 to the central portion 2c of the jacket 2.

[0054] In the preferred embodiment, the tapered portion 7 may be obtained by squashing the jacket 2 by applying an even pressure radially towards the axis of symmetry of the jacket.

[0055] This pressure must be high enough for elastic failure setting the portion of the jacket 2 which constitutes the tapered portion 7.

[0056] Advantageously, the first zone 8 of the tapered portion 7 has a length L, that is to say extension in a direction parallel with the main direction of extension X of the jacket 2, substantially equal to the internal working length L1 of the sleeve 6.

[0057] In the embodiment illustrated, the sleeve 6 is in particular easy to obtain by filling the jacket 2 with the core 3 only up to a distance from the second end 2b equal to L1.

[0058] In contrast, the tapered portion 7 is filled with inert material 4 as far as the first end 2a, so that the free end 7a of the tapered portion 7, once inserted in the sleeve 6 of another pile 1, makes contact with the inert material 4 of the pile receiving said tapered portion 7.

[0059] In this way, advantageously, the connection of two or more piles 1 to one another ideally forms a single modular jacket completely filled with inert material.

[0060] Such a result can be achieved with a different embodiment, not illustrated, involving, in place of the sleeve 6 aligned with the jacket 2 and the tapered portion 7, a sleeve 6 with a cross-section greater than the jacket 2 designed to receive inside it the first end 2a, not squashed, (and filled with the core) of a jacket 2 of another pile 1.

[0061] Said solution can be achieved either by applying on the outside of the second end 2a and axially projecting from it (for example by welding, squashing, screwing, etc.), a specific sleeve 6, or by widening the jacket 2 at and near to the second end 2b to form a widened portion of it (deformation similar but opposite to that required to obtain the tapered portion 7).

[0062] It must also be emphasised that the thickness of the jacket 2 is preferably practically constant along the entire length of the jacket 2, in other words the central portion 2c and the two end portions 2a, 2b of the jacket have the same thickness specified above (even if due to the tapering the tapered portion may actually be slightly thicker).

[0063] This characteristic, together with the partial filling of the jacket 2 with the core 3 of inert material 4, and the fact that the jacket is made of stainless steel, allows the pile 1 to have a very high ultimate compression strength.

[0064] For example, a pile 1 with a diameter of approximately 4.8 cm and thickness of 1.5 mm can withstand a compression load of more than 20,000 kg and a working bearing capacity, in operation, which may reach 10,000 kg.

[0065] It is important to specify that the production of the core 3 of the pile 1 with inert material 4 must be performed before the pile 1 is installed and preferably after production of the tapered portion 7. Moreover, the inert material 4 must be allowed to harden sufficiently before the pile 1 can be used.

[0066] In practice, to strengthen building foundations, the pile 1 is driven into the ground with the tapered portion 7 downwards and the sleeve 6 upwards.

[0067] Once the pile has been almost completely inserted in the ground, the tapered portion 7 of another pile 1 is inserted in the sleeve 6 of the pile already driven into the ground.

[0068] By applying downward pressure on the second pile, the assembly consisting of the two piles further penetrates the ground.

[0069] The operation goes on with the connection to one another of several piles until the force required to make the assembly consisting of the plurality of piles connected to one another penetrate the ground reaches a predetermined value matching the weight force which the assembly must support in operation. At this point, the assembly of piles is connected to the foundations, using known methods which are therefore not described, to help the foundations support the building.

[0070] As can easily be deduced from the above, the pile for strengthening building foundations disclosed allows the production of a modular pile assembly.

[0071] The invention described above therefore achieves the preset aims.

[0072] The fact that the jacket of the pile for strengthening building foundations disclosed is made of stainless steel allows the pile to resist corrosion, even in the presence of high levels of moisture and mineral salts.

[0073] Moreover, despite the pile being made of stainless steel, the fact that the pile consists of a steel jacket with limited thickness and a core of inert material significantly reduces the production costs.

[0074] In addition, despite the reduced thickness of the jacket, the fact that the core consists of inert material, combined with the mechanical properties of the jacket, means that it can support significant loads.

[0075] Moreover, the modularity of the piles allows smaller piles to be used, guaranteeing that they are easier to handle.

[0076] Also, the fact that the piles are driven into the ground until a predetermined thrust force is needed allows the certainty that they will support a predetermined load.

Claims

1. A pile for strengthening building foundations, characterised in that it comprises:

- an outer jacket (2) made of stainless steel and having, transversally to the main direction of extension (X) of the pile, a dimension of between 3 and 15 cm, and a thickness of between 0.8 and 5 mm;

- a core (3) inside the jacket (2) and at least partly consisting of an inert material (4); and

- engagement means (5) attached to at least a first end (2a) of the jacket (2) for allowing connection to a second end (2b) of the jacket of another pile (1),

and also being characterised in that the pile is a modular element.

2. The pile according to claim 1, wherein the jacket (2) is between 1 and 3 mm thick.

3. The pile according to claim 2, wherein the jacket (2) is 1.5 mm thick.

4. The pile according to any of the foregoing claims, wherein the engagement means (5) are also attached to a second end (2b) of the jacket (2) opposite the first end (2a), creating a central portion (2c) of jacket (2) without engagement means (5).

5. The pile according to claim 4, wherein the engagement means (5) comprise a sleeve (6) located at the second end (2b) of the jacket (2); the sleeve (6) being able to engage with the first end (2a) of another pile.

6. The pile according to claim 5, wherein the sleeve (6) consists of a portion of the jacket (2) extending from the second end (2b) by a predetermined length (L1), the core not being present at the portion of the jacket (2) forming the sleeve (6).

7. The pile according to claim 6, wherein the sleeve (6) has, transversally to the main direction of extension (X) of the jacket (2), a dimension equal to or greater than the transversal dimension of the central portion (2c) of the jacket (2).

8. The pile according to claim 5, wherein the sleeve (6) is fixed to the jacket (2) axially and projecting from it starting from the second end (2b) by a predetermined length (L1), the core not being present at the sleeve (6).

9. The pile according to claim 8, wherein the sleeve (6) has, transversally to the main direction of extension (X) of the jacket (2), a dimension greater than the central portion (2c) of the jacket (2).

10. The pile according to any of the claims from 5 to 9, wherein the engagement means (5) comprise a tapered portion (7) of the jacket (2) located at the first end (2a) of the jacket (2).

11. The pile according to claim 5 or 6, wherein the tapered portion (7) comprises a first zone (8) with a dimension transversal to the main direction of extension (X) of the jacket (2) which is less than the transversal dimension of the central portion (2c) of the jacket (2) and a second zone (9) for connecting the first zone (8) of the tapered portion (7) and the central portion (2c) of the jacket (2) .

12. The pile according to claim 11, wherein the first zone (8) of the tapered portion (7) extends with a predetermined length (L) in a direction parallel with the main direction of extension (X) of the jacket (2); the tapered portion (7) of the jacket (2) also being filled with the core of inert material (4).

13. The pile according to claim 12 and any of the claims from 6 to 9, wherein the sleeve (6) and the tapered portion (7) are at least partly shaped to fit each other, the length (L1) of the sleeve (6) being substantially equal to the length (L) of the tapered portion (7).

14. The pile according to any of the foregoing claims, wherein the inert material (4) is a cement-based mix.

15. The pile according to claim 14, wherein the cement-based mix is concrete with a low particle size distribution enriched with hardening additives.

16. The pile according to any of the foregoing claims, wherein the inert material (4) comprises one or more synthetic compounds.

17. The pile according to any of the foregoing claims, wherein the core of inert material is reinforced with metal elements.

18. The pile according to any of the foregoing claims, wherein the core (3) is made in such a way that when two piles (1) are connected using the engagement means (5) the core (3) of one pile (1) makes contact with the core of the other pile (1).

19. A method for producing a pile for strengthening building foundations, characterised in that it comprises the steps of preparing a stainless steel tubular jacket (2) with predetermined length, preparing engagement means (5) on at least a first end (2a) of the tubular jacket (2) to allow connection of two consecutive piles, at least partly filling the tubular jacket (2) with an inert material (4).

20. The method according to claim 19, wherein the step of preparing engagement means (5) comprises the step of elastic failure setting the first end (2a) of the tubular jacket (2) to produce a tapered portion (7).

21. The method according to claim 19 or 20, wherein the step of preparing engagement means (5) comprises the step of preparing a sleeve (6) on a second end (2b) opposite the first end (2a) of the tubular jacket (2) .

22. The method according to claim 21, wherein the step of preparing a sleeve (6) comprises the step of not filling the second end (2b) of the tubular jacket with the inert material (4).

23. The method according to any of the claims from 15 to 19, wherein the step of preparing a tubular jacket (2) comprises the step of preparing a jacket with a thickness of between 0.8 and 5 mm, preferably between 1 and 1.5 mm.

24. The method according to claim 19 or 20, wherein the step of preparing a tubular jacket (2) comprises the step of preparing a tubular jacket (2) with a diameter of between 3 and 15 cm, preferably between 7 and 10 cm.

25. Use of a pile according to one or more of the claims from 1 to 18 to strengthen the foundations of a building by driving the pile into the ground.

26. The use according to claim 25, wherein the pile 1 is driven into the ground through a hole made in the foundations of a building.

27. The use according to claim 25 or 26, wherein the pile 1 is driven into the ground until the resistance offered by the ground is less than a predetermined value.

28. The use according to claim 25, 26 or 27, wherein a plurality of said piles axially connected to one another by the engagement means is driven into the ground one after another.

Drawing