Apparatus and method for the construction of drilled foundation piles

Abstract

The present disclosure relates to an apparatus (100) for making drilled foundation piles comprising a rod body (10), which has a bottom end (11), and a bucket body (20) shaped as a hollow cylinder and associated along an upper base surface (21) of the cylinder to the rod body (10), at the bottom end (11). Further, the rod body (10) is configured to be rotated by drive means (50) to allow a rotation of the bucket body (20). Furthermore, the apparatus (100) comprises at least one extractable flap (30) connected to the bucket body (20) and configured to assume a retracted configuration and at least one extracted configuration. In particular, in the at least one extracted configuration the at least one extractable flap (30) protrudes or protrudes with respect to the side surface of the bucket body (20), towards the outside of the bucket body (20), by a greater length than in the retracted configuration. The present disclosure also concerns a method for the construction of stepped drilled foundation piles using such an apparatus (100).

Description

[0001] APPARATUS AND METHOD FOR THE CONSTRUCTION OF DRILLED FOUNDATION PILES

[0002] DESCRIPTION

[0003] The present disclosure relates generally to the field of drilled foundation piles. In particular, the present disclosure relates to an apparatus for the construction of drilled foundation piles and further relates to a method for making drilled foundation piles.

[0004] In the construction of foundations for buildings or infrastructures with high loads and / or in cases where the base soil is such that direct foundations are not sufficient, the use of foundation piles to support the loads of the overlying structure is well known.

[0005] Among the different types of foundation piles, drilled piles are very common and are realised by removing soil during excavation using rotary tools such as 'buckets'. In the case of high-strength or rocky soils, drills or core barrels are known to be used for excavation.

[0006] The basis of the present disclosure is a recognition on the part of the inventor of the present disclosure that apparatuses for making drilled foundation piles such as those made available by the prior art, while advantageous in many respects, have certain limitations.

[0007] Specifically, according to the prior art, medium and large-diameter drilled piles are used, depending both on the loads from the superstructure and on the consistency and therefore the strength and deformability parameters of the layers crossed.

[0008] Particularly in the case of large-diameter piles, it can be difficult to excavate in rocky or high-strength layers, so more suitable tools are usually used to perform part of the excavation. For example, core barrels for rocks are usually used to excavate layers of higher strength.

[0009] Furthermore, in the case of large-diameter piles, excavation in high-strength soils is all the more difficult the greater the depth, as the excavation apparatus must withstand high stresses especially at the tip of the apparatus, i.e. the portion at greatest depth.

[0010] Therefore, in the case of large-diameter piles, excavation to great depths and / or high-strength layers is currently complex and time-consuming, affecting the entire construction process.

[0011] The present disclosure starts from the position of the technical problem of providing an apparatus and method for the construction of drilled foundation piles to meet the needs mentioned above with reference to the prior art and / or to achieve further advantages.

[0012] This is achieved by means of an apparatus and a method according to the respective independent claims. Secondary characteristics of the object of the present disclosure are defined in the corresponding dependent claims.

[0013] In particular, in accordance with the present disclosure, in order to improve the prior art, it is proposed to make an apparatus for making drilled foundation piles comprising a rod body and a bucket body (also known as a "bucket") conformed as a hollow cylinder and associated with the rod body along an upper base surface of the cylinder. Specifically, the bucket body is associated at a bottom end of the rod body.

[0014] In addition, the rod body is configured to be rotated by means of drive means to allow rotation of the bucket body and the apparatus further comprises at least one extractable flap, connected to the bucket body and configured to assume a retracted configuration and at least one extracted configuration.

[0015] At least one extractable flap can preferably be attached to the bucket body along the upper base surface of the bucket body, or along a lower portion of the side surface of the bucket body.

[0016] In the context of the present disclosure, the terms "upper" and "lower" are understood relative to the direction of excavation in the ground, i.e., an upper portion is a portion of the bucket body intended to remain more towards, or near, the surface than a lower portion of the bucket body, during the excavation operations of drilled foundation piles.

[0017] In particular, in the fully extracted configuration the at least one extractable flap protrudes or juts out from the side surface of the bucket body, towards the outside of the bucket body, by a greater length than in the retracted configuration.

[0018] According to a form of embodiment, in the retracted configuration the at least one extractable flap is arranged flush with a side surface of the bucket body, or is arranged inwards or is retracted with respect to the side surface of the bucket body towards the inside of the bucket body. Alternatively, in the retracted configuration the at least one extractable flap protrudes or juts out with respect to the side surface of the bucket body towards the outside of the bucket body by a shorter length than in the extracted configuration.

[0019] That is, the at least one extractable flap is adjustable between the retracted configuration and the at least one extracted configuration.

[0020] Furthermore, it is proposed to realise a method for the construction of drilled foundation piles using such an apparatus. Namely, the apparatus for the construction of drilled foundation piles enables the realisation of such a method, which provides:

[0021] - a first drilling phase in which the extractable flap is in a retracted configuration and the bucket body (or 'bucket') is rotated to dig into the ground in a vertical direction down to an initial depth, so as to form a hole in the ground;

[0022] - a second phase in which the at least one extractable flap configuration is changed from the retracted configuration to the at least one extracted configuration,

[0023] - a third drilling phase in which the bucket body (or 'bucket') is rotated to dig into the hole in the ground down to a second depth.

[0024] In particular, the second depth is less deep in the vertical direction in the ground with respect to the first depth.

[0025] In other words, in the first phase the apparatus is used to preferably drill the entire final depth of the foundation pile with a first diameter, while in the second phase it is preferably drilled with a second diameter, larger than the first diameter, along a shallower section of the ground, i.e. down to the second depth, which is shallower than the first depth.

[0026] For example, in the second phase, it may be planned to excavate a first soil layer until a second soil layer is reached, where the second soil layer is more consistent and / or more resistant to drilling than the first soil layer.

[0027] Consequently, according to the present disclosure, it is possible to obtain stepped drilled foundation piles, i.e. with two or more different diameters depending on the excavation depth.

[0028] That is to say, the bored piles obtainable by means of the apparatus and method according to the present disclosure are of a stepped type, i.e. they have two or more sections each having a respective diameter different from a diameter of the other sections. In other words, along the longitudinal direction of the foundation pile obtainable by means of the apparatus and method according to the present disclosure there are two or more sections each having a respective diameter, and in particular the greater the depth in the ground in which the section is located, the smaller the diameter of the section itself.

[0029] Therefore, by means of the apparatus and method according to the present disclosure, it is proposed to realise a technological advancement with respect to the known drilled foundation piles, through the realisation of stepped drilled foundation piles, understood in the sense of the present disclosure, i.e. wherein the pile diameter decreases with depth assuming discrete values, i.e. constant values within the single longitudinal section of the pile.

[0030] In this way, it is possible to obtain drilled foundation piles with larger diameters at shallower depths, i.e. where the soil is generally less consistent and more easily excavated. In addition, it is possible to obtain drilled foundation piles with smaller diameters at greater depths, i.e. where the soil generally has greater consistency and / or strength and is therefore more difficult to excavate.

[0031] It is therefore clear that by using the apparatus and method according to this disclosure, it is possible to reduce the cost and time of excavating piles especially at greater depths.

[0032] In addition, according to this disclosure, it can be envisaged to improve the seismic resistance of the foundation pile by excavating to a depth equal to a larger diameter even within the more substantial layer, so as to increase the stiffness properties of the foundation pile.

[0033] Furthermore, according to the present disclosure, it is possible to improve the resistant section of drilled foundation piles in such a way as to obtain greater resistance at the stiffness interface between a more consistent layer and a less consistent layer of soil. Such an improvement is particularly useful in conditions of seismic risk.

[0034] Further advantages, features and ways of using the subject matter of this disclosure will be evident from the following detailed description of its forms of implementation, presented for illustrative and non-limiting purposes.

[0035] It is, however, evident that each form of realisation of the subject matter of this disclosure may present one or more of the advantages listed above; in any case, it is not required that each form of realisation present all the advantages listed simultaneously.

[0036] Reference will be made to the figures in the attached drawings, where:

[0037] Figure 1 shows a side view of an apparatus according to a form of embodiment of the present invention, in which the extractable flap is connected to the upper base surface of the bucket body and is in the retracted configuration, and in which the rod body is shown only for part of its length;

[0038] Figure 2 shows a side view of the apparatus in Figure 1 , in which the extractable flap is in an extracted configuration;

[0039] Figure 3 shows a perspective view of a detail of the apparatus in Figure 1 ;

[0040] Figures 4A and 4B show two schematic views of stepped drilled foundation piles obtained by means of embodiments of an apparatus and a method according to the present disclosure;

[0041] Figure 5 shows a side view of an apparatus according to an alternative embodiment of the present invention, in which the extractable flap is connected to a lower portion of the side surface of the bucket body and is in the extracted configuration.

[0042] With reference to the attached figures, a form of construction of an apparatus for drilled foundation piles is indicated with the reference number 100.

[0043] The apparatus 100 comprises a rod body 10, which has a bottom end 11 , and a bucket body 20, which is shaped like a hollow cylinder and is associated with the rod body 10 along an upper base surface 21 of the bucket body 20, at the bottom end 11 of the rod body 10.

[0044] In particular, the rod body 10 is configured to be rotated by drive means 50, for example an internal combustion engine, such as a rotary engine, or an electric motor, to allow rotation of the bucket body 20.

[0045] The apparatus 100 further comprises at least one extractable flap 30 connected to the bucket body 20 and configured to assume a retracted configuration and at least one extracted configuration.

[0046] In particular, in the at least one extracted configuration the at least one extractable flap 30 protrudes or juts out from the side surface of the bucket body 20, towards the outside of the bucket body 20, by a greater length than the retracted configuration.

[0047] The at least one extractable flap 30 is then configured to allow an increase in the excavation hole diameter, from the retracted configuration to the at least one extracted configuration, by enlarging the total diameter of the apparatus in a plane perpendicular to the longitudinal axis of the cylinder-shaped bucket body 20.

[0048] The at least one extractable flap 30 may be connected to the bucket body 20 along an upper portion of the bucket body 20, for example along the upper surface 21 (as illustrated in Figures 1, 2 and 3), or along a lower portion of the bucket body 20, for example along a lower portion of the side surface of the bucket body 20 (as illustrated in Figure 5).

[0049] According to a form of embodiment, in the retracted configuration the at least one extractable flap 30 is arranged flush with a side surface of the bucket body 20, or is arranged inwards or is retracted with respect to the side surface of the bucket body 20 towards the interior of the latter. Alternatively, in the retracted configuration the at least one extractable flap 30 protrudes or juts out with respect to the side surface of the bucket body 20, towards the outside of the bucket body 20, by a shorter length than in the extracted configuration, in which the at least one extractable flap preferably protrudes or juts out by the maximum length with respect to the side surface of the bucket body 20

[0050] In other words, the at least one extractable flap may assume at least two configurations, a retracted configuration and at least one extracted configuration. In particular, in the at least one extracted configuration, the at least one extractable flap 30 protrudes or juts out relative to the side surface of the bucket body 20 more than in the retracted configuration, in which the at least one extractable flap 30 may be configured to protrude or jut out relative to the side surface of the bucket body 20, or to be flush with the side surface of the bucket body 20, or to retract relative to the side surface of the bucket body 20.

[0051] Considering a plane perpendicular to the longitudinal axis of the cylinder-shaped bucket body 20, in the retracted configuration the at least one extractable flap 30 lies on said plane more internally (with respect to the longitudinal axis of the bucket body 20) than in the at least one extracted configuration, in which the at least one extractable flap 30 lies on said plane more externally (with respect to the longitudinal axis of the bucket body 20).

[0052] For example, in an embodiment the at least one extractable flap 30 lies on said plane entirely within, or flush with, the circumference formed by the side surface of the cylinder-shaped bucket body 20, whereas in the at least one extracted configuration, the at least one extractable flap 30 lies on said plane at least partially outside the circumference formed by the side surface of the cylinder-shaped bucket body 20.

[0053] Preferably, in the retracted configuration the at least one extractable flap 30 is positioned flush with the outer circumference of the bucket body 20, i.e. with the side surface of the bucket body 20, while in the at least one extracted configuration the at least one extractable flap 30 protrudes or juts out with respect to the outer circumference of the bucket body 20, i.e. with respect to the side surface of the bucket body 20.

[0054] Preferably, for example, in the at least one extracted configuration the at least one extractable flap 30 protrudes by a value between 10 cm and 20 cm from the outer circumference of the bucket body 20.

[0055] In the context of the present disclosure, the expressions "inwardly" or "outwardly" referring to the cylinder-shaped bucket body 20 are to be understood with respect to the interior or exterior of the circumference formed by the side surface of the bucket body 20 in the plane perpendicular to the longitudinal axis of the bucket body 20. That is to say, in the plane perpendicular to the longitudinal axis of the cylinder-shaped bucket body 20, the lateral surface of the cylinder forms a circumference with respect to which it is to be assessed whether the at least one extractable flap 30 is inside or outside the circumference, i.e. whether it retracts or protrudes with respect to the bucket body 20.

[0056] Preferably, the at least one extractable flap 30 comprises a fixed portion 31, connected to the bucket body 20, and a movable portion 32, configured to be moved in such a way that the at least one extractable flap 30 alternately assumes one between the retracted configuration and the at least one extracted configuration.

[0057] Even more preferably, the fixed portion 31 of the at least one extractable flap 30 is connected to the bucket body 20 along the upper base surface 21 of the cylinder-shaped bucket body. That is, the cylinder-shaped bucket body 20 has a connecting portion along its upper base surface 21 , and preferably the fixed portion 31 of the at least one extractable flap 30 and the bottom end 11 of the rod body 10 are connected to the bucket body 20 along the connecting portion disposed on the upper base surface 21. Preferably, the connecting portion does not cover the entire upper base surface 21, for example it may be substantially rectangularly shaped extending along a portion of the upper base surface 21.

[0058] Alternatively, the fixed portion 31 of the at least one extractable flap 30 may be connected to the bucket body 20 along a lower portion of the side surface of the bucket body 20, i.e. , along the side surface and near the lower base surface of the bucket body 20.

[0059] For example, in the case where the at least one extractable flap 30 is connected to the bucket body 20 along a lower portion of the lateral surface of the bucket body 20, a hole or opening for sliding the at least one extractable flap between the retracted configuration and the at least one extracted configuration may be provided on the lateral surface of the bucket body 20. In this case, for example, the fixed portion 31 of the at least one extractable flap 30 may be connected internally to the side surface of the bucket body 20, i.e., inside the bucket body 20 along an inner wall of the bucket body 20. Preferably also, the movable portion 32 may be configured to slide through the hole or opening in the side surface of the bucket body 20 to switch between the retracted configuration and the at least one extracted configuration.

[0060] Preferably, the bucket body 20 has a lower base surface that is at least partially hollow, i.e. at least partially absent, to allow the passage of material into the bucket body 20 during excavation of the hole for the drilled foundation pile.

[0061] Preferably, moreover, the fixed portion 31 of the at least one extractable flap 30 is connected to the bucket body 20 either by bolting or by welding.

[0062] According to an embodiment, the movable portion 32 of the at least one extractable flap 30 comprises a extractable element 32a, configured to be at least partially extractable or retractable with respect to the fixed portion 31, and a tip element 32b, connected to an end of the retractable element 32a opposite to the fixed portion 31.

[0063] In other words, the movable portion 32 has a extractable element 32a comprising a first region configured, for example, to slide from the inside to the outside of the fixed portion 31 of the extractable flap 30, or vice versa, when it transitions from the retracted configuration to the at least one extracted configuration, or vice versa. Furthermore, preferably the tip member 32b is connected to the rectractable member 32a at a second region of the movable portion 32 opposite the first region.

[0064] Preferably, in the at least one extracted configuration the tip member 32b of the at least one extractable flap 30 protrudes or juts out from the side surface of the bucket body 20, towards the outside of the bucket body 20, by a greater length than in the retracted configuration.

[0065] For example, in an embodiment, in the retracted configuration the tip member 32b of the at least one extractable flap 30 is disposed flush with a side surface of the bucket body 20 or is arranged inwards or is retracted relative to the side surface of the bucket body 20, inwardly of the bucket body 20. Further, in the at least one extracted configuration, the tip member 32b of the at least one extractable flap 30 protrudes or juts out relative to the side surface of the bucket body 20, towards the outside of the bucket body 20.

[0066] Alternatively, the tip element 32b may protrude or jut out relative to the lateral surface of the bucket body 20, towards the outside of the bucket body 20, in both the retracted configuration and the extracted configuration. In particular, in the at least one extracted configuration, the tip element 32b may protrude or jut out relative to the side surface of the bucket body 20, towards the outside of the bucket body 20, by a greater length than in the retracted configuration.

[0067] Preferably, the tip element 32b is connected to the end of the removable element 32a opposite the fixed portion 31 by a weld. For example, such a weld may be a Widia weld.

[0068] According to one embodiment, the apparatus 100 comprises two extractable flaps 30 arranged on the upper base surface 21 of the bucket body 20, or along a lower portion of the side surface of the bucket body 20, symmetrically with respect to a longitudinal axis of the bucket body 20.

[0069] The apparatus may also comprise three or more extractable flaps 30, preferably arranged on the upper base surface 21 of the bucket body 20 or along a lower portion of the side surface of the bucket body 20, symmetrically with respect to a longitudinal axis of the bucket body 20.

[0070] According to a preferred embodiment, the bucket body 20 has a base diameter of between 400 mm and 2000 mm, and the at least one extractable flap 30 in the at least one extracted configuration protrudes or protrudes with respect to the side surface of the bucket body 20, outwards of the bucket body 20, by a value between 100 mm and 200 mm more with respect to the retracted configuration. That is, by switching from the retracted configuration to the at least one extracted configuration the extractable flap 30, in particular the tip element 32b, is moved outwards with respect to the lateral surface of the bucket body 20 preferably by between 100 mm and 200 mm.

[0071] Preferably, the at least one extractable flap 30 is configured to assume a first extracted configuration and a second extracted configuration. Specifically, in the first extracted configuration the at least one extractable flap 30 protrudes or juts out relative to the side surface of the bucket body 20 outwardly of the bucket body 20 by a greater length than in the second extracted configuration. That is, in the second extracted configuration the at least one extractable flap 30 protrudes or juts out with respect to the side surface of the bucket body 20 towards the outside of the bucket body 20 by a shorter length than in the first extracted configuration.

[0072] In particular, preferably in both the first extracted configuration and the second extracted configuration the at least one extractable flap 30 protrudes or juts out from the side surface of the bucket body 20 outwards from the bucket body 20 by a greater length than in the retracted configuration.

[0073] A further object of the present disclosure is a method for constructing drilled foundation piles, in particular stepped drilled foundation piles, using an apparatus 100 according to one of the described embodiments. In particular, the method comprises the following steps:

[0074] - a first drilling phase in which the at least one extractable flap 30 is in a retracted configuration and the bucket body 20 is rotated to drill a first hole in the ground in a vertical direction down to a first depth P1, i.e. preferably to the full final depth of the foundation pile,

[0075] - a second step of changing the configuration of the at least one extractable flap 30, wherein the at least one extractable flap 30 is switched from the retracted configuration to the at least one extracted configuration,

[0076] - a third drilling phase wherein the bucket body 20 is rotated to drill the first hole in the ground down to a second depth P2, i.e. to drill a larger diameter hole down to the second depth P2.

[0077] In particular, the second depth P2 is less deep than the first depth P1, so that in the third phase the diameter of the first hole is enlarged down to the second depth P2. That is to say, in the first drilling phase the apparatus 100 drills deeper than in the third drilling phase.

[0078] This method can be used, for example, to construct a two-diameter foundation pile, i.e. one with a first diameter for the entire depth of the pile and a second diameter from ground level to the second depth P2, where the first diameter is smaller than the second diameter.

[0079] In other words, during the first phase the apparatus 100 excavates to the first depth P1 a hole of a first diameter D1 equal to the base diameter of the bucket body 20. Subsequently in the second phase the at least one extractable flap 30 is made to change from the retracted configuration to the at least one extracted configuration, such that during the third phase the apparatus drills so as to enlarge the diameter of the borehole from the first diameter D1 to a second diameter D2, which is greater than the first diameter D1, down to a second depth P2 which is shallower than the first depth P1, i.e. comprised between the ground level and the first depth P1.

[0080] For example, as illustrated in Figure 4A, the second depth P2 may represent the depth of a first soil layer below which a second soil layer is present, at least down to a first depth P1. In particular, the deeper second soil layer may have a greater consistency and / or resistance to drilling.

[0081] Preferably, moreover, after the third phase in which the largest diameter bore was drilled to the second depth P2, it is possible to return the at least one extractable flap 30 to the retracted configuration and perform a cleaning phase of the excavation down to the first depth P1 in order to remove any excavation residue, e.g. excavated soil, from the bottom of the bore of the drilled foundation pile.

[0082] According to an embodiment, e.g. to realise a three-diameter stepped bored pile, in the second stage the at least one extractable flap 30 is moved from the retracted configuration to the first extracted configuration, and the method further involves

[0083] - a fourth step in which the at least one extractable flap 30 configuration is changed from the first extracted configuration to the second extracted configuration,

[0084] - a fifth drilling phase in which the bucket body 20 is rotated to drill into the hole down to a third depth P3.

[0085] In particular, the third depth P3 lies between the second depth P2 and the first depth P1.

[0086] That is to say that in this embodiment in the fourth stage the at least one extractable flap 30 is moved from the first extracted configuration to the second extracted configuration, such that during the fifth stage the apparatus 100 drills in such a way as to enlarge the diameter of the hole from the first diameter D1 to a third diameter D3, which is greater than the first diameter D1 and less than the second diameter D2, down to a third depth P3 shallower than the first depth P1, i.e. between the first depth P1 and the second depth P2. For example, as illustrated in Figure 4B, the second depth P2 may represent the depth of a first soil layer, below which there is a second soil layer down to a third depth P3, and also below the second soil layer there is a third soil layer down to at least a first depth P1. In particular, as one descends to greater depths, the soil layers may have a greater consistency and / or resistance to drilling than the upper layers. That is, for example, the third layer may be more consistent or resistant than the second layer, which in turn may be more consistent or resistant than the first layer.

[0087] Consequently, the apparatus 100 and the method described in this disclosure make it possible to overcome the limitations of the prior art and achieve several advantages.

[0088] In particular, by means of apparatus 100, it is possible to drill a hole in the ground at a small diameter, allowing even stronger layers to be drilled with greater ease, and subsequently expand the diameter of the hole only down to an intermediate depth, by means of the use of at least one extractable flap, allowing an improvement in the bearing capacity of the foundation pile.

[0089] It is clear that the apparatus and method according to the present disclosure result in cost and time savings compared to the prior art, as the excavation of larger and / or stronger layers is simplified and the use of multiple excavation tools is not required.

[0090] Furthermore, it is noted that by means of the apparatus and the method according to the present disclosure, improved safety can be achieved compared to the prior art, as they allow for a lower risk of tool failure in light of the smaller excavation diameter at greater depths. That is to say, according to the present disclosure, the improved scalability of the apparatus can lead to a reduction in the number of accidents that sometimes lead to a breakage of the excavation tools in very consistent and / or resistant soil layers. Therefore, the risk of damage to the drilling tools is improved by means of the apparatus and the method according to the present disclosure.

[0091] Furthermore, using the apparatus and method according to the present disclosure, depending on the excavation depth, which is shallower for the stepped bored piles, less soil can be removed for the construction of the stepped bored foundation piles, and the risk of intercepting any groundwater during excavation, which would significantly slow down the construction of the bored foundation piles, can also be reduced.

[0092] The subsequent steps in the fabrication of the drilled foundation piles, such as the steps of pouring the concrete and placing the iron reinforcements in the hole obtained by the claimed apparatus and method, are known to the skilled person in the art and are therefore not described within the present disclosure. Specifically, by using the apparatus and method according to this disclosure, depending on the excavation depth, which is shallower for stepped drilled piles, it is possible to achieve a greater speed in the placement of reinforcement and concrete, and it is also possible to reduce the amount of concrete used in the construction of bored foundation piles.

[0093] The subject matter of the present disclosure has thus far been described with reference to its embodiments. It is to be understood that there may be other embodiments pertaining to the same inventive core, all of which fall within the scope of protection of the claims set forth below.

Claims

CLAIMS1. Apparatus (100) for the construction of drilled foundation piles comprising:- a rod body (10) with a bottom end (11),- a bucket body (20) shaped like a hollow cylinder and associated along an upper base surface (21) of said cylinder to said rod body (10) at said bottom end (11), wherein said rod body (10) is configured to be rotated by means of drive means (50) to allow a rotation of said bucket body (20), and wherein said apparatus (100) comprises at least one extractable flap (30) connected to said bucket body (20) and configured to assume a retracted configuration and at least one extracted configuration, wherein in said at least one retracted configuration said at least one extractable flap (30) protrudes or juts out with respect to a lateral surface of said bucket body (20) towards the outside of said bucket body (20) by a greater length with respect to said retracted configuration.

2. Apparatus (100) according to the preceding claim, wherein in said retracted configuration said at least one extractable flap (30) is arranged flush with said lateral surface of said bucket body (20) or is arranged inwards or retracted with respect to said lateral surface of said bucket body (20) towards the inside of said bucket body (20), and wherein in said at least one extracted configuration said at least one extractable flap (30) protrudes or juts out with respect to said lateral surface of said bucket body (20) towards the outside of said bucket body (20).

3. Apparatus (100) according to claim 1 or 2, wherein said at least one extractable flap (30) comprises a fixed portion (31), connected to said bucket body (20), and a movable portion (32), configured to be moved in such a manner as to cause said at least one extractable flap (30) to alternately assume one of said retracted configuration and said at least one extracted configuration.

4. Apparatus (100) according to the preceding claim, wherein said fixed portion (31) of said at least one extractable flap (30) is connected to said bucket body (20) along said upper base surface (21).

5. Apparatus (100) according to any one of claims 1 to 3, wherein said fixed portion (31) of said at least one extractable flap (30) is connected to said bucket body (20) along a lower portion of said side surface of said bucket body (20).

6. Apparatus (100) according to any one of claims 3, 4 or 5, wherein said fixed portion (31) of said at least one extractable flap (30) is connected to said bucket body (20)by bolting or by welding.

7. Apparatus (100) according to any one of claims 3 to 6, wherein said movable portion (32) of said at least one extractable flap (30) comprises an extractable element (32a), configured to be at least partially extractable or retractable with respect to said fixed portion (31), and a tip element (32b), connected to an end of said extractable element (32a) opposite to said fixed portion (31).

8. Apparatus (100) according to the preceding claim, wherein in said at least one extracted configuration said tip element (32b) of said at least one extractable flap (30) protrudes or juts out with respect to said lateral surface of said bucket body (20) outwardly of said bucket body (20) by a greater length with respect to said retracted configuration.

9. Apparatus (100) according to claim 7 or 8, wherein said tip element (32b) is connected to said end of said extractable element (32a) opposite to said fixed portion (31) by welding.

10. Apparatus (100) according to any one of the preceding claims, wherein said apparatus (100) comprises two extractable flap (30) disposed on said upper base surface (21) of said bucket body (20), or along a lower portion of the lateral surface of said bucket body (20), symmetrically with respect to a longitudinal axis of said bucket body (20).

11. Apparatus (100) according to any one of the preceding claims, wherein said bucket body (20) has a base diameter of between 400 mm and 2000 mm, and wherein said at least one extractable flap (30) in said at least one extracted configuration protrudes or juts out with respect to said side surface of said bucket body (20) outwardly of said bucket body (20) by a length of between 100 mm and 200 mm more with respect to said retracted configuration.

12. Apparatus (100) according to any one of the preceding claims, wherein said at least one extractable flap (30) is configured to assume a first extracted configuration and a second extracted configuration, wherein in said first extracted configuration said at least one extractable flap (30) protrudes or juts out with respect to said lateral surface of said bucket body (20) outwardly of said bucket body (20) by a greater length than in said second extracted configuration.

13. Method for making drilled foundation piles using an apparatus (100) according to any one of claims 1 to 12, wherein said method comprises the following steps:- a first drilling phase in which said at least one extractable flap (30) is in a retracted configuration and said bucket body (20) is rotated to drill into the ground in a vertical direction down to a first depth (P1 ), so as to form a first hole in the ground,- a second step of changing the configuration of the at least one extractable flap (30),wherein said at least one extractable flap (30) is switched from the retracted configuration to the at least one extracted configuration,- a third drilling phase in which said bucket-shaped body (20) is rotated to drill into said first hole down to a second depth (P2), where said second depth (P2) is less deep than said first depth (P1).

14. Method according to the preceding claim by means of an apparatus (100) according to claim 12, wherein in said second step said at least one extractable flap (30) is switched from the retracted configuration to the first extracted configuration, and wherein said method further provides: - a fourth step of changing the configuration of the at least one extractable flap (30), wherein said at least one extractable flap (30) is switched from the first extracted configuration to the second extracted configuration,- a fifth drilling phase in which said bucket body (20) is rotated to drill into said hole down to a third depth (P3), where said third depth (P3) is comprised between said second depth (P2) and said first depth (P1).

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