Support ribs for foundation pit and method for manufacturing support structure in foundation pit

Abstract

The rib (10) for supporting a foundation pit comprises at least one structural element (12) and at least one connecting assembly (14) for connecting the structural element of the rib relative to the structural element of an adjacent rib (10"), wherein the connecting assembly (14) comprises a male connecting element (30) and a female connecting element (32); the male connecting element comprises a head (26) and a neck (24) and the female connecting element comprises a retaining element (40), the head (26) being capable of being inserted into the female connecting element (32") of the connecting assembly (14") of the adjacent rib (10") so that the retaining element (40") of the female connecting element (32") of the adjacent rib (10") retains the neck (24).

Description

Technical Field

[0001] The invention relates to a supporting rib of an excavation and a method for manufacturing a supporting structure in an excavation.

[0002] The invention has been developed in a non-limiting manner, in particular with reference to ribs which are provided with connecting elements between adjacent ribs for producing a supporting structure and reinforcing a foundation pit, for example for the production of a road or railway tunnel. Background Art

[0003] It is known to reinforce a foundation pit, for example, for a tunnel, by using a supporting arch known as a rib. In particular, a rib generally comprises a plurality of structural elements formed by steel and mutually connected to form an arch. Such an element consists of an open or closed profile with a cross section of various types (e.g., C-shaped, H-shaped, T-shaped or circular). Typically, the profile is formed by a structural workshop and then connected to each other at the construction site of the foundation pit to be reinforced to form a rib. After assembly, each rib is connected to an adjacent rib via a suitable connecting element. Then, shotcrete (gunned concrete) is generally used to reinforce the space between two consecutive ribs and the wall of the foundation pit.

[0004] A method for installing a support structure and for reinforcing a foundation pit is known from document EP 2354447, which describes a reinforcement structure for a foundation pit in which a plurality of ribs are connected to each other by using chains. Each connecting chain is engaged at a first end with a first connecting ring welded to a first rib and at a second end with a second connecting ring welded to a second rib.

[0005] This system has been found to be effective, but it has a number of disadvantages: the chain must be manually engaged with the connecting ring and the operation is complicated. If it is found that the chain is not properly engaged after the ribs are installed, it may be necessary to reposition the ribs to repeat the engagement operation.

[0006] Document EP 3152400 describes a connection system between ribs that provides a rod that slides inside the rib to be fixed and is inserted by snap-fit ​​into the head of the fixing rod of the adjacent rib already fixed. This connection system has been found to be effective, but it requires a given precision during the alignment between successive rods, which is not always easy to comply with. Summary of the invention

[0007] One object of the present invention is to overcome the disadvantages of the prior art and to provide a rib provided with connecting elements which are even quicker and easier to put in place and which reduce the risk of accidental detachment.

[0008] Furthermore, it is intended to provide a rib of any cross section, open or closed, comprising a hollow cross section to be filled with a fast, easy and rapid connection element, for example with concrete. Another object is to provide a rib that is economical and reliable during use and fixing.

[0009] Another object of the invention is to provide a method for installing a structure consisting of a plurality of ribs in a simple manner and which is stable and reliable.

[0010] According to a first aspect, a rib for supporting a foundation pit is described, the rib comprising at least one structural element and at least one connecting element or connecting assembly for connecting the structural element of the rib relative to the structural element of an adjacent rib. The connecting assembly may comprise a male engaging member or element and a female engaging member or element. The male engaging element of the rib may thus easily and quickly engage with the female engaging member of an adjacent rib, thereby producing a stable connection.

[0011] The male engagement element may include a head and a neck. The female engagement element may include a retaining element or member. The head of the male engagement element may be capable of being inserted into the female engagement element of the connecting assembly of the adjacent rib. The retaining element of the female engagement element of the adjacent rib may thereby retain the neck.

[0012] According to another aspect, the retaining member of the female engagement element can be an elastically deformable retaining member. For example, it can be a washer or an escutcheon. More specifically, it can be a Belleville spring washer. In particular, it is a Belleville spring washer with grooves, i.e. a Belleville spring washer provided with tabs or plates.

[0013] According to another aspect, the Belleville spring washer may be received within the bowl member.

[0014] According to another aspect, the Belleville spring washer may include a tab which is inclined at an angle greater than 0° relative to a plane defined by the outer edge of the Belleville spring washer. Preferably, the tab may be inclined towards the inner side of the bowl-shaped member. This configuration of the female engagement element allows the male engagement element to be inserted therein without the male engagement element having to be along the same axis as the female engagement element. Thus, the male engagement element may be inserted at an angle of 10°. Naturally, this greater flexibility makes it possible to facilitate the connection operation between multiple ribs.

[0015] According to another aspect, the female coupling element may include a cap that is capable of retaining the Belleville spring washer within the bowl-shaped member. The cap may have a flared opening. The flared opening may be inclined at an angle equal to the angle of inclination of the tab. In this way, when positioning and connecting the two ribs, any traction tending to pull the two ribs apart is supported primarily by the cap, rather than solely by the tab of the Belleville spring washer. As a result, a much greater resistance is obtained. In addition, the risk of accidental separation is generally eliminated. In fact, the tab supported against the inclined opening of the cap cannot be sufficiently deformed to allow the head of the male coupling element to pass through.

[0016] According to another aspect, the connection assembly may further comprise a rod, and one of the male and female engagement elements, preferably the male engagement element, may be arranged at a first end of the rod. The second end of the rod may be selectively fixable to at least one structural element of the rib. Preferably, it may be screwed to a threaded connector, which is fixed to at least one structural element of the rib. Preferably, the threaded connector is welded to at least one structural element of the rib.

[0017] According to another aspect, one of the male and female engagement elements, preferably the female engagement element, is fixed to at least one structural element of the rib in a stable manner, preferably by welding.Preferably, the bowl-shaped member of the female engagement element can be fixed to at least one structural element of the rib in a stable manner.

[0018] According to another aspect, a method for producing a support structure for a foundation pit is described, the support structure comprising at least a first rib and a second rib having some or all of the above-described features. The method may include the step of positioning the first rib and the second rib at a predetermined distance from each other in the foundation pit. It may include the step of inserting a male engagement element of a connection assembly of the second rib into a female engagement element of the first rib.

[0019] A connection system between a first rib and a second rib adjacent to the first rib is also described. The connection system may include a male engagement element disposed on the first rib and a female engagement element disposed on the second rib. The male engagement element may include a head and a neck, the neck having a lateral dimension that is smaller than the corresponding lateral dimension of the head. The female engagement element of the second rib may include a retaining member. The head of the male engagement element of the first rib can be inserted into the female engagement element of the second rib so that the retaining member of the female engagement element of the second rib retains the neck of the male engagement element of the first rib. The housing for the retaining member includes an abutment surface, and the retaining member moves to abut against the abutment surface under the action of a traction force tending to move the first rib away from the second rib. The abutment surface prevents the release of the head of the male engagement element of the first rib. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further features and advantages will be understood from the following detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, which are provided by way of non-limiting examples only and in which:

[0021] - Figure 1 A cross section of a rib is shown, wherein the connecting components between the ribs are partial cross-sections;

[0022] - Figure 2 An overall view of the support structure of the foundation pit formed by a plurality of ribs is shown;

[0023] - Figure 3 showing the step of engaging a connection assembly of a rib relative to a connection assembly of an adjacent rib; and

[0024] - Figure 4 Detail of a connection assembly of a rib engaging with a connection assembly of an adjacent rib is shown. DETAILED DESCRIPTION

[0025] refer to Figure 1 , a rib 10 for supporting a foundation pit comprises at least one structural element 12. In the exemplary case shown, the structural element has a circular cross section, is hollow and can be filled with concrete. As is known in the art, a single rib can include a plurality of structural elements to be connected to each other to create a generally arched structure.

[0026] The rib further comprises a connecting assembly 14 connecting the structural element 12 to the structural element of an adjacent rib.The term "adjacent" is intended to be understood as referring to a rib located before or after the rib in question and spaced apart by a predetermined distance.

[0027] The connection assembly 14 comprises a rod 16 which is connected to the structural element 12 at a first end 17. The connection is preferably formed by a threaded coupling 18 which is fixed to the structural element 12 in a stable manner, into which the first end 17 provided with a thread is screwed for this purpose. The figure shows a weld bead 20 which fixes the threaded coupling 18 to the structural element 12.

[0028] The second end 22 of the rod has a neck 24 and a head 26. The head is preferably spherical and has a diameter greater than the diameter of the neck. It can be noted that in the embodiment shown, the rod, the neck and the head have a circular cross section. However, if the head 26 has a transverse dimension greater than the neck, a completely different cross section is not excluded. In other words, an undercut 28 must be present between the head and the neck.

[0029] The head and the neck together constitute a male engagement element 30 which is engageable with a corresponding female engagement element 32 of an adjacent rib.

[0030] The female engagement element 32 comprises a bowl-shaped member 34 which is welded to the structural element 12 at the side opposite to the threaded coupling 18 by a weld bead 36 .

[0031] The retaining member 40 is positioned on the opening 38 of the bowl-shaped member 34. The retaining member is a grooved Belleville spring washer 40. Thus, the retaining member is an annular object having a truncated conical sloping wall 42, a central hole 44 and an outer edge 46; the sloping wall is subdivided into a plurality of tabs 48 arranged in a circular manner. The spring is preferably made of spring steel so that each tab 48 can be elastically deformed. At rest, the tabs 48 are inclined toward the inside of the bowl-shaped member 34 at an angle A greater than 0° relative to the plane defined by the outer edge 46 of the Belleville spring washer.

[0032] The cap 50 holds the Belleville spring washer against the opening 38 of the bowl-shaped member 34. The cap is preferably screwed onto the bowl-shaped member and even more preferably welded to the bowl-shaped member, for example by a weld bead 52, to obtain maximum holding properties. The cap 50 has a base 54 of frustoconical shape with a central hole 56, which can be circular or of other shapes. In other words, it has an open opening. The hole 56 has a dimension greater than the transverse dimension of the head 26. The inner face or surface 58 is preferably inclined inwardly at an angle B. The angle B is equal to or in any case similar to the angle of inclination A of the tab 48 of the Belleville spring washer. The term "similar" is understood to have a difference of at most 15°.

[0033] The Belleville spring washer is sized to receive and retain the head 26. Thus, the diameter of its hole 44 is smaller than the diameter of the head 26 and greater than or equal to the diameter of the neck 24.

[0034] A plurality of ribs as described above can be used to form a support structure 1 of a foundation pit, such as Figure 2 shown.

[0035] In a first step, if the first rib 10" consists of two structural elements 12", these two structural elements are connected to each other. Thus, the rib 10" is positioned in the foundation pit. The second rib 10 is then mounted and positioned at a predetermined distance from the first rib. The connecting assembly 14, in particular the rod 16, is fixed to the second rib 10 and screwed into the threaded coupling 18. The male coupling element 30 of the second rib 10 is inserted into the female coupling element 32" of the first rib, as in Figure 3 In particular, the head 26 of the connecting assembly 14 of the second rib 10 is inserted into the hole 56" of the cap 50" and into the hole 44" of the Belleville spring washer 40", pressing on the tab 48", which becomes elastically deformed. The insertion can also be performed by tilting the holding rod 16 relative to the axis of the female coupling element 32". Therefore, perfect alignment is not required during assembly.

[0036] When the head 26 of the connecting assembly 14 of the second rib 10 is inserted into the Belleville spring washer 40 ″ of the first rib 10 ″, the tab 48 ″ returns to its original position, thereby retaining the head 26 by the neck 24 .

[0037] Thus, if necessary, the positioning of the second rib 10 can be improved. Once the ribs are connected and correctly positioned, stresses tending to move the two ribs 10", 10 away from each other will be supported by the cap 50" and in particular by its frustoconical base 54", as in Figure 4 In fact, since the inner face or inner surface 58" of the frustoconical base has an inclination similar to that of the tabs 48" of the Belleville spring washer 40" (that is, since angle A is similar to angle B), the tabs 48" are supported against the inner surface of the frustoconical base of the cap, which prevents them from deforming and thus preventing the head 26 of the male engagement element 30 of the second rib 10 from being released. As mentioned above, the hole 56 has a suitable size so that it allows the passage of the head 26 and at the same time is small enough to prevent reverse deformation of the tab and thus prevent the release of the head 26. Therefore, the hole 56 has a size that allows the head 26 to be inserted freely.

[0038] The strength of the connection between two adjacent ribs 10 ″, 10 is therefore given by the resistance of the joint between the respective components and not by the generally smaller resistance of the Belleville spring washer 40 ″. It can further be noted that the above-described construction practically eliminates the risk of accidental separation, since once the head 26 is retained by the Belleville spring washer 40 ″, it cannot be released. Therefore, an irreversible connection is involved.

[0039] Once the second rib 10 is correctly positioned, the third rib 10 ′ can be positioned in the same way, and so on, until the ribs are positioned on the entire pit portion to be reinforced, thereby forming the supporting structure 1 of the pit.

[0040] It is understood that the configuration including the bowl-shaped member and the cap and shown in the accompanying drawings should be considered as an example of a housing for the retaining member 40, which includes an abutment surface 58 for the retaining member 40. When a traction force tending to move the two ribs connected to each other apart is applied, that is, when the head of the male engagement element 30 of the second rib is pulled toward the outside of the female engagement element, the retaining member 40 rests on the abutment surface 58, so that the abutment surface 58 presses on the retaining member 40. The abutment surface 58 is configured to prevent the head 26 of the male engagement element 30 of the second rib from releasing under the action of the traction force tending to move the two ribs connected to each other apart. In more detail, the abutment surface 58 ensures that the size of the central hole 44 of the retaining member remains smaller than the transverse size of the head 26, thereby preventing or limiting deformation of the retaining member.

[0041] For example, the abutment surface 58 and its opening 56 may be of such dimensions that during use, a major portion of the retaining member 40 moves into abutment with the abutment surface 58. If the retaining member is a Belleville spring washer, the abutment surface 58 is of such dimensions that during use, at least a portion of the tab 48 rests on the abutment surface. For optimal operation, the abutment surface 58 has an inclination similar to the inclination of the tab 48 of the Belleville spring washer 40.

[0042] The figure shows a retaining member in the form of a slotted Belleville spring washer having a tab with an angle A greater than zero. However, the angle A may be equal to 0°. Thus, more generally, the retaining member may be an elastic washer or an escutcheon, i.e. an annular object with a hole 44, which is usually made of metal and in particular spring steel and has internal teeth. The retaining member enables it to deform under the effect of the pressure of the head of the male engaging member to allow the head of the male engaging member to pass through the hole 44 and thus allow the connection between the ribs. The retaining member may also be represented using the term circular fixing member.

[0043] Therefore, a retaining member having an angle A greater than 0° (i.e., a grooved Belleville spring washer) is preferred because, due to the conical configuration, the retaining member is able to support greater stress depending on whether the pressure of the head 26 in one direction is greater than the pressure in another direction. Therefore, the retaining member 40 can be oriented so that, as shown in the figure, the concave surface points outwardly so as to deform with relative ability to receive the head 26 of the male engagement element 30 when a connection is made between two ribs, and so as to provide greater resistance to separation. It will be appreciated that the abutment surface 58 having an angle of inclination B similar to the angle of inclination A prevents the retaining member 40 from deforming in the presence of a traction force intended to separate the ribs, and therefore constitutes the element that best helps prevent separation between the ribs.

[0044] Another advantage of the retaining member having an angle A greater than 0° is given by the fact that the abutment surface 58, as shown in the figure, can constitute the surface of a frustoconical wall (base 54 of cap 50), which on the outside constitutes an open opening, which facilitates the insertion of the head 26 and therefore facilitates the connection process between the ribs.

[0045] Naturally, while the principle of the invention remains unchanged, the embodiments and construction details may vary widely with respect to what has been described and illustrated, without thereby departing from the scope of the present invention.

[0046] Example

[0047] Even though the present invention is defined by the appended claims, it should be understood that the invention may alternatively be defined according to the following embodiments.

[0048] Embodiment 1. A rib (10) for supporting a foundation pit, the rib (10) comprising at least one structural element (12), and at least one connecting assembly (14) for connecting the structural element of the rib to the structural element (12") of an adjacent rib (10"), wherein the connecting assembly (14) comprises a male connecting element (30) and a female connecting element (32), the male connecting element comprising a head (26) and a neck (24) and the female connecting element comprising a retaining member (40), the head (26) being insertable into the female connecting element (32") of the connecting assembly (14") of an adjacent rib (10") so that the retaining member (40") of the female connecting element (32") of the adjacent rib (10") retains the neck (24).

[0049] Embodiment 2. A rib according to the preceding embodiment, wherein the retaining member (40) of the female engagement element (32) is a grooved Belleville spring washer.

[0050] Embodiment 3. The rib according to the preceding embodiment, wherein the Belleville spring washer (40) is received within the bowl member (34).

[0051] Embodiment 4. The rib according to the preceding embodiment, wherein the bowl spring (40) comprises a tab (48) inclined at an angle (A) greater than 0° relative to a plane defined by an outer edge (46) of the Belleville spring washer (40).

[0052] Embodiment 5. A rib according to the preceding embodiment, wherein the female engaging element (32) further comprises a cap (50) capable of retaining the disc spring washer (40) within the bowl-shaped member (34), the cap (50) having an open opening inclined at an angle (B) equal to or similar to the inclination angle (A) of the tab.

[0053] Embodiment 6. The rib according to any of the preceding embodiments, wherein the connection assembly (14) further comprises a rod (16), one of the male engagement element (30) and the female engagement element (32) being disposed at the first end (22) of the rod.

[0054] Embodiment 7. The rib according to the preceding embodiment, wherein the second end (17) of the rod (16) is selectively fixable to at least one structural element (12) of the rib.

[0055] Embodiment 8. The rib according to any of the preceding embodiments, wherein one of the male engagement element (30) and the female engagement element (32) is fixed to at least one structural element (12) of the rib in a stable manner.

[0056] Embodiment 9. The rib according to the preceding embodiment, wherein the bowl-shaped member (34) is fixed to at least one structural element (12) of the rib (10) in a stable manner.

[0057] Embodiment 10. A method for manufacturing a support structure for a foundation pit, the support structure comprising at least a first rib (10") and a second rib (10) according to embodiments 1 to 9, the method comprising the steps of:

[0058] - positioning the first rib (10") and the second rib (10) at a predetermined distance from each other in the foundation pit,

[0059] - Inserting the male engagement element (30) of the connection assembly (14) of the second rib (10) into the female engagement element (32") of the first rib (10").

Claims

1. A rib (10'') for supporting a foundation pit, the rib (10'') comprising at least one structural element (12''), and at least one connecting assembly (14'') for connecting the structural element of the rib to the structural element (12) of a similar adjacent rib (10), wherein the connecting assembly (14'') comprises a male engaging element (30'') and a female engaging element (32''), wherein the male engaging element comprises a head (26'') and a neck (24''), wherein the neck has a lateral dimension that is smaller than a corresponding lateral dimension of the head (26''), and wherein the female engaging element comprises a retaining member (40'') housed in a housing, wherein the female engaging element (32'') is capable of receiving the head (26) of the male engaging element (30) of the connecting assembly (14) of a similar adjacent rib (10) so that the retaining member (40'') of the female engaging element (32'') of the rib (10'') retains the neck (24) of the male engaging element (30) of the similar adjacent rib (10), wherein the housing for the retaining member (40'') includes an abutment surface (58''), and under the action of a traction force tending to move the rib (10'' away from the adjacent rib (10), the retaining member (40'') moves to abut against the abutment surface, thereby preventing the release of the head (26) of the male engaging element (30) of the adjacent rib (10), wherein The retaining member (40") of the female engagement element (32) is a grooved Belleville spring washer, comprising a tab (48) which is inclined at an inclination angle (A) greater than 0° relative to a plane defined by an outer annular edge (46) of the Belleville spring washer, and wherein an abutment surface (58) is inclined at an angle (B), and the difference between the angle (B) of the abutment surface (58) and the inclination angle (A) of the tab is at most 15°.

2. The rib according to claim 1, wherein: The retaining member (40") rests over its main portion on the abutment surface (58).

3. The rib according to claim 1, wherein: The retaining member (40") of the female engagement element (32) is elastically deformable.

4. The rib according to claim 3, wherein: The retaining member (40") of the female engagement element (32) is a washer.

5. The rib according to claim 1, wherein: The Belleville spring washer is received within the bowl member (34) and retained by the cap (50).

6. The rib according to any one of the preceding claims 1 to 5, wherein: The abutment surface (58) has a central opening (56) having a size greater than a transverse dimension of the head (26), and the retaining member has an opening (44) that is smaller than the size of the head (26) and greater than or equal to the size of the neck (24).

7. The rib according to any one of the preceding claims 1 to 5, wherein: The connection assembly (14) further includes a rod (16) with one of a male engagement element (30) and a female engagement element (32) disposed at a first end (22) of the rod.

8. The rib according to claim 7, wherein: The second end (17) of the rod (16) is selectively fixable to the at least one structural element (12) of the rib.

9. The rib according to any one of the preceding claims 1 to 5, wherein: One of the male engagement element (30) and the female engagement element (32) is fixed to the at least one structural element (12) of the rib in a stable manner.

10. The rib according to claim 9, wherein: The bowl-shaped member (34) is fixed to the at least one structural element (12) of the rib (10) in a stable manner.

11. A method for manufacturing a support structure for a foundation pit, the support structure comprising at least one rib according to any one of claims 1 to 10, the at least one rib comprising a first rib (10'') and a second rib (10), the method comprising the steps of: - positioning the first rib (10") and the second rib (10) at a predetermined distance from each other in the foundation pit, - Inserting the male engagement element (30) of the connecting assembly (14) of the second rib (10) into the female engagement element (32'') of the first rib (10'').

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