CN113015843B - Support ribs for foundation pit and method for manufacturing support structure in foundation pit - Google Patents

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

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

Technical Field

The invention relates to a support rib for a foundation pit (excavation) and to a method for producing a support structure in a foundation pit.

The invention has been developed in a non-limiting manner, in particular with reference to ribs provided with connecting elements between adjacent ribs for producing a support structure and reinforcing a foundation pit, for example for manufacturing a road or railway tunnel.

Background

It is known to strengthen foundation pits, for example for tunnels, by using support arches called ribs. In particular, the rib generally comprises a plurality of structural elements formed of steel and mutually connected to form an arch. Such elements consist of open or closed profiles with various types of cross-section, for example C-shaped, H-shaped, T-shaped or circular. Typically, profiles are formed by structural workshops and then connected to each other at the construction site of the foundation pit to be reinforced to form ribs. After assembly, each rib is connected to an adjacent rib via a suitable connecting element. Then, shotcrete (shotcrete) is often used to reinforce the space between two consecutive ribs and the wall of the foundation pit.

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

This system has been found to be effective, but has a number of drawbacks in that the chain must be manually engaged with the connecting ring and the operation is complex. If the chain is found to be incorrectly engaged after the ribs are installed, it may be necessary to reposition the ribs to repeat the engagement operation.

Document EP 3152400 describes a connection system between the ribs, which 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 bars, which is not always easy to follow.

Disclosure of Invention

It is an object of the present invention to overcome the drawbacks of the prior art and to provide a rib provided with a connecting element which is even faster and easier to place in place and reduces the risk of accidental detachment.

Furthermore, it is intended to provide an open or closed rib of any cross section, including a hollow cross section filled with quick, easy and quick connecting elements (e.g. with concrete). Another object is to provide a rib that is economical and reliable during use and securement.

Another object of the invention is to provide a method for mounting in a simple manner a structure that is composed of a plurality of ribs and that is stable and reliable.

According to a first aspect, a rib for supporting a foundation pit is described, which rib may comprise at least one structural element, and at least one connection element or connection assembly for connection of the structural element of the rib relative to the structural element of an adjacent rib. The connection assembly may include a male engagement member or element and a female engagement member or element. The male engagement elements of the ribs can thus easily and quickly engage with the female engagement members of an adjacent rib, resulting in a stable connection.

The male engagement element may include a head and a neck. The female engagement element may comprise 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 connection assembly of adjacent ribs. The retaining elements of the female engagement elements of adjacent ribs may thereby retain the neck.

According to another aspect, the retaining member of the female engagement element may be an elastically deformable retaining member. For example, it may be a gasket or escutcheon. More specifically, it may be a belleville washer. In particular, it is a slotted belleville washer, i.e. a belleville washer provided with tabs or plates.

According to another aspect, a belleville spring washer may be received within the bowl.

According to another aspect, the belleville washer may include a tab that is inclined at an angle greater than 0 ° relative to a plane defined by an outer edge of the belleville washer. Preferably, the tab may be inclined towards the inside of the bowl-like 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 co-axial with 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 the plurality of ribs.

According to another aspect, the female engagement element may comprise a cap configured to retain the belleville washer within the bowl member. The cap may have a flared (flared) opening. The flared opening may be inclined at an angle equal to the inclination angle of the tab. In this way, when positioning and connecting the two ribs, any traction forces tending to pull them apart are supported mainly by the cap and not only by the tabs of the belleville washers. Thus, a much greater resistance is obtained. Furthermore, the risk of accidental separation is generally eliminated. In fact, the tab, which is supported against the inclined opening of the cap, cannot be sufficiently deformed to allow the passage of the head of the male engagement element.

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 provided at the first end of the rod. The second end of the rod may be selectively securable to at least one structural element of the rib. Preferably, it can be screwed to a threaded coupling fixed to at least one structural element of the rib. Preferably, the threaded coupling is welded to at least one structural element of the rib.

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, preferably by welding, in a stable manner. Preferably, the bowl-shaped member of the female engagement element may be fixed to at least one structural element of the rib in a stable manner.

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 features described above. The method may comprise the step of positioning the first rib and the second rib at a predetermined distance from each other in the foundation pit. It may comprise the step of inserting the male engagement element of the connection assembly of the second rib into the female engagement element of the first rib.

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 comprise a head and a neck having a lateral dimension smaller than a corresponding lateral dimension of the head. The female engagement element of the second rib may comprise 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 such 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 against which the retaining member moves under the influence of a traction force tending to move the first rib away from the second rib. The abutment surface prevents release of the head of the male engagement element of the first rib.

Drawings

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 example only and in which:

Figure 1 shows a section of a rib, wherein the connection assembly between the ribs is a partial cross section;

figure 2 shows a general view of a support structure of a foundation pit formed by a plurality of ribs;

Figure 3 shows the joining step of the connection assembly of a rib with respect to the connection assembly of an adjacent rib, and

Figure 4 shows a detail of the connection assembly of a rib engaged with the connection assembly of an adjacent rib.

Detailed Description

Referring to fig. 1, a rib 10 for supporting a foundation pit includes 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 may include a plurality of structural elements to be connected to each other to create a generally arch-shaped structure.

The ribs further include a connection assembly 14 that connects the structural element 12 to the structural element of an adjacent rib. The term "adjacent" is intended to be understood as meaning ribs which are assigned to be in front of or behind the rib in question and which are spaced apart by a predetermined distance.

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

The second end 22 of the stem 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 will be noted that in the illustrated embodiment, the stem, neck and head have circular cross-sections. However, if the head 26 has a transverse dimension greater than the neck, a completely different cross-section is not precluded. In other words, there must be an undercut 28 between the head and neck.

The head and neck together constitute a male engagement element 30, said male engagement element 30 being capable of engaging with a corresponding female engagement element 32 of an adjacent rib.

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

The retaining member 40 is positioned over the opening 38 of the bowl member 34. The retaining member is a slotted belleville washer 40. The retaining member is thus an annular object having a frustoconical inclined wall 42, a central aperture 44 and an outer edge 46, the inclined wall being subdivided into a plurality of tabs 48 arranged in a circular manner. The springs are preferably made of spring steel so that each tab 48 can be elastically deformed. At rest, the tab 48 is inclined toward the inside of the bowl-shaped member 34 at an angle a of greater than 0 ° relative to the plane defined by the outer edge 46 of the belleville washer.

The cap 50 retains the belleville washer against the opening 38 of the bowl member 34. The cap is preferably screwed onto the bowl and even more preferably welded to the bowl, for example by a weld bead 52, to obtain maximum retention characteristics. The cap 50 has a frustoconical base 54, the base 54 having a central aperture 56, the central aperture 56 may be circular or other shape. In other words, it has a flared opening. The aperture 56 has a dimension that is greater than the lateral dimension of the head 26. The inner face or surface 58 is preferably inclined inwardly at an angle B. Angle B is equal to or in any case similar to the angle a of inclination of the tab 48 of the belleville washer. The term "similar" is understood to have a maximum difference of 15 °.

The belleville washer is sized to receive and retain the head 26. Thus, the diameter of its bore 44 is smaller than the diameter of the head 26 and greater than or equal to the diameter of the neck 24.

A plurality of ribs as described above may be used to form the support structure 1 of the foundation pit, as shown in fig. 2.

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 within the foundation pit. The second rib 10 is then installed and positioned at a predetermined distance from the first rib. The connection assembly 14, in particular the rod 16, is fixed to the second rib 10 and screwed into the threaded coupling 18. The male engagement element 30 of the second rib 10 is inserted into the female engagement element 32 "of the first rib, as can be better seen in the detailed view of fig. 3. In particular, the head 26 of the connection 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 washer 40", pressing on the tab 48", said tab 48" becoming elastically deformed. Insertion may also be performed by tilting the retaining rod 16 relative to the axis of the female engagement element 32 ". Thus, no perfect alignment is required during assembly.

When the head 26 of the connection assembly 14 of the second rib 10 is inserted into the belleville washer 40 "of the first rib 10", the tab 48 "returns to its original position, thereby retaining the head 26 by the neck 24.

Thus, if necessary, the positioning of the second rib 10 can be improved. Once the ribs are connected and properly positioned, the 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 seat 54", as can be seen in the detailed view of fig. 4. In fact, since the inner face or surface 58 "of the frustoconical seat has an inclination similar to that of the tabs 48" of the belleville washer 40 "(that is, since the angle a is similar to the angle B), the tabs 48" are supported against the inner surface of the frustoconical seat of the cap, which prevents them from deforming and therefore prevents the head 26 of the male engagement element 30 of the second rib 10 from being released. As mentioned above, the aperture 56 is of a suitable size such that it allows the head 26 to pass through and is at the same time small enough to prevent reverse deformation of the tab and thus release of the head 26. Thus, the bore 56 has a size that allows the head 26 to be inserted with play.

Thus, the strength of the connection between two adjacent ribs 10", 10 is given by the resistance of the joint between the various components and not by the normally smaller resistance of the belleville washer 40". It may further be noted that the above configuration virtually eliminates the risk of accidental separation, since the head 26 cannot be released once the head 26 is held by the belleville washer 40 ". Thus, an irreversible connection is involved.

Once the second rib 10 is correctly positioned, the positioning of the third rib 10' can be performed in the same way and so on until the rib is positioned over the entire foundation pit section to be reinforced, thereby forming the support structure 1 of the foundation pit.

It will be appreciated that the configuration comprising the bowl-shaped member and the cap and shown in the drawings should be considered as an example of a housing for the retaining member 40, the housing comprising 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, i.e. when the head of the male engagement element 30 of the second rib is pulled towards the outside of the female engagement element, the retaining member 40 rests on the abutment surface 58, whereby 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 being released under the effect of a 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 bore 44 of the retaining member remains less than the lateral dimension of the head 26, thereby preventing or limiting deformation of the retaining member.

For example, the abutment surface 58 and its opening 56 may be sized such that, during use, a substantial portion of the retaining member 40 moves into abutment with the abutment surface 58. If the retaining member is a belleville washer, the abutment surface 58 has a size such that at least a portion of the tab 48 rests on the abutment surface during use. For optimal operation, the abutment surface 58 has a slope similar to that of the tab 48 of the belleville washer 40.

The figure shows a retaining member in the form of a slotted belleville 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 escutcheon, i.e. an annular object with a bore 44, typically made of metal and in particular spring steel and having internal teeth. The retaining member is such that it can deform under the pressure of the head of the male engagement member to allow the head of the male engagement member to pass through the aperture 44 and thus allow connection between the ribs. The holding member may also be referred to using the term circular fixation member.

Therefore, a retaining member having an angle a greater than 0 ° (i.e., a fluted disc spring washer) is preferred because, due to the conical configuration, the retaining member is able to support greater stress depending on whether the head 26 is pressed in one direction than the other. Thus, the retaining member 40 may be oriented such that the concavity points outwardly as shown in the figures to deform with opposing capacity to receive the head 26 of the male engagement element 30 when the connection is made between two ribs and to provide greater resistance to separation. It will be appreciated that the abutment surface 58 having an angle of inclination B similar to angle of inclination a prevents deformation of the retaining member 40 in the presence of traction intended to separate the ribs, and thus constitutes the element most conducive to preventing separation between the ribs.

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

Naturally, the principle of the invention remaining unchanged, the embodiments and constructional details may vary widely with respect to what has been described and illustrated, without thereby departing from the scope of the present invention.

Examples

Even though the invention is defined by the appended claims, it should be understood that the invention may alternatively be defined according to the following examples.

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

Embodiment 2. The rib according to the previous embodiment, wherein the retaining member (40) of the female engagement element (32) is a fluted disc spring washer.

Embodiment 3. The rib according to the previous embodiment, wherein a belleville washer (40) is received within the bowl member (34).

Embodiment 4. The rib according to the previous embodiment, wherein the bowl-shaped spring (40) comprises a tab (48) inclined at an angle (a) greater than 0 ° with respect to a plane defined by the outer edge (46) of the belleville washer (40).

Embodiment 5. The rib according to the previous embodiment, wherein the female engagement element (32) further comprises a cap (50), said cap (50) being capable of retaining the belleville washer (40) within the bowl-shaped member (34), the cap (50) having a flared opening inclined at an angle (B) equal or similar to the inclination angle (a) of the tab.

Embodiment 6. The rib of any of the preceding embodiments, wherein the connection assembly (14) further comprises a stem (16), one of the male (30) and female (32) engagement elements being disposed at the first end (22) of the stem.

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

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

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

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:

positioning a first rib (10 ') and a second rib (10') at a predetermined distance from each other in the foundation pit,

-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").