A method for repairing a construction structure, and a load-bearing element resulting from the method.

Abstract

To repair a construction structure comprising an initial structure at a location intended to support a load, a shoring structure is installed. Since the initial structure has at least one longitudinal section (4) between a lower end and an upper end, the shoring structure includes a concrete shell (20) installed around the longitudinal section (4) such that the concrete shell (20) supports at least part of the load in place of the longitudinal section (4). A gap (25) is present between the concrete shell (20) and the longitudinal section (4) so ​​that the concrete shell (20) is not directly stressed in the event of transverse deformation of the longitudinal section (4). (See Figure 2 for more details.)

Description

Title of the invention: Method for repairing a construction work, and load-bearing element resulting from the method Technical field

[0001] The present invention relates to techniques for repairing works of art. Prior art

[0002] The load-bearing structures of construction works often comprise elements such as piers, posts, pylons or the like, surmounted by parts of the work whose load is transferred to the ground or an underlying structure by means of these elements. In many cases, these load-bearing elements extend vertically. But their longitudinal direction may also have an inclination, in the case of inclined struts or crutches for example.

[0003] It happens that such a load-bearing element is defective and must be replaced or supplemented by a new and healthy structure.

[0004] The load-bearing element to be repaired has not necessarily lost all of its capacity to support the loads that are theoretically applicable to it. The failure may be due to multiple reasons, such as: - poor design or poor execution of the load-bearing element which is not suitable for fulfilling the expected function; - damage following an accident or action on the structure (impact on a bridge pier for example); - pathology affecting one of the constituent materials of the load-bearing element; - upgrading the structure to support higher loads.

[0005] Among the pathologies of concrete as a constituent material of the load-bearing element, we can cite internal sulphate reactions (ISR), in particular the delayed formation of ettringite (DEF: "Delayed Ettringite Formation"). In the case of steel or reinforced concrete, the pathology can be linked to the corrosion of the steel.

[0006] Up to a certain degree of structural defect or pathology, it is possible to reinforce the load-bearing element. Methods of confinement by carbon reinforcement or by shells of prestressed ultra-high performance fiber-reinforced concrete (UHPC) imparting radial pressure can prove effective when the projected loads induce states close to a centered compression. Such a method is described in patent EP 3 455 412.

[0007] If the bending moments experienced by the load-bearing element are too high, or if the pathology observed is too advanced, these methods may prove insufficient. In these situations, the faulty load-bearing element must generally be demolished and replaced. by a sound definitive structure, which requires the installation of a temporary structure to support the load of the work.

[0008] The installation and removal of such a temporary structure, as well as the demolition and reconstruction of the faulty load-bearing element, are costly operations, sometimes made more difficult by operational maintenance requirements or difficulties in accessing the area around the structure.

[0009] There is therefore a need for a repair technique which overcomes at least some of the above problems. Summary

[0010] A method of repairing a construction work is provided. The construction work comprises an initial structure at a location intended to support a load of the work. The initial structure comprises at least one longitudinal portion between a lower end and a higher end. The method uses a shoring structure and comprises: - install around the longitudinal portion a concrete envelope belonging to the shoring structure so that the concrete envelope supports at least part of the load of the structure in place of the longitudinal portion. A gap is maintained between the concrete envelope and the longitudinal portion so that the concrete envelope is not directly stressed in the event of transverse deformation of the longitudinal portion.

[0011] The shoring structure is built around the existing initial structure and it integrates a load transfer device. The method allows, if desired, to preserve the general architecture of the existing structure by creating an exo-structure around it.

[0012] The work can be accomplished without demolishing the initial structure, and without necessarily mobilizing a temporary structure, even if the existing structure is seriously degraded.

[0013] By providing the gap between the concrete envelope and the longitudinal portion of the initial structure, certain deformations of the defective initial structure can be accommodated without disturbing the shoring structure. This is particularly the case for transverse deformations which may appear if the longitudinal portion of the initial structure is affected by the RSI.

[0014] The gap also allows for no, or almost no, longitudinal forces to be transmitted by friction or shear in the gap between the initial structure and the added exo-structure.

[0015] There may be certain local connections between the concrete envelope and the longitudinal portion of the initial structure, in particular if the capacity deficiency of the initial supporting structure is partial (poor design, or modification of the specifications). loads during the life of the structure for example).

[0016] If, on the other hand, the capacity deficiency of the initial supporting structure is total (pathologies such as RSI, or advanced corrosion for example), it is appropriate for the exo-structure to be independent from a structural point of view, or even completely isolated, from the initial structure. In this case, there will be no mechanical connection, apart from possible point supports in order to prevent local instabilities of the concrete envelope.

[0017] Depending on the case, the shoring structure may take all or only part of the load of the structure.

[0018] An embodiment of the method further comprises: - place a flexible material around the longitudinal portion before installing the concrete envelope, to maintain the gap between the concrete envelope and the longitudinal portion.

[0019] The flexible materials that can be used include elastomers, expanded polymers such as polystyrene or honeycomb structures, particularly cardboard.

[0020] The construction of the exo-structure attached to the initial structure, through the intermediate layer of flexible material placed in the gap, is a practical and economical choice. This support can also play a temporary role in preventing lateral (transverse) instabilities of buckling or warping of the shell elements (prefabricated or sprayed concrete) of the exo-structure, in particular when the latter is not complete (closed section). If it is necessary to prevent this type of instability permanently, it will be useful to secure the opposite shells or panels by elements put in place by drilling through the initial structure when the configuration allows it, in order to preserve as much as possible the independence between the two structures.

[0021] In one embodiment of the method, the installation of the concrete envelope comprises: - arrange longitudinal panels between the lower end and the upper end of the longitudinal portion of the initial structure; and - add concrete around the longitudinal portion, between the longitudinal panels, to form keying portions connecting the longitudinal panels to each other.

[0022] The concrete applied between the longitudinal panels may in particular be BFUP, which, in certain embodiments, is sprayed to form the keying portions.

[0023] The BFUP can in particular be sprayed onto the flexible material placed around the longitudinal portion.

[0024] To form the longitudinal panels, prefabricated sections can be placed end to end between the lower end and the upper end of the longitudinal portion. longitudinal section of the initial structure. Prestressing reinforcement can then be inserted into longitudinal conduits formed in the prefabricated sections of the longitudinal panels, and the prestressing reinforcement can be tensioned and anchored.

[0025] In one embodiment of the method, the initial structure further comprises a transverse portion extending transversely to the longitudinal portion at the upper end thereof, the transverse portion comprising two opposite main faces, the method further comprising: - install two transverse concrete panels, belonging to the shoring structure, parallel to the main faces of the transverse portion, so that the load of the structure is supported by the concrete envelope via the transverse panels.

[0026] The two transverse panels of the shoring structure can be secured to each other by at least one crosspiece.

[0027] An embodiment of the method further comprises: - insert prestressing reinforcements into longitudinal conduits formed in the concrete envelope and extending into the transverse panels; and - tighten and anchor the prestressing reinforcements.

[0028] An embodiment of the method further comprises: - transfer the load of the structure onto temporary support devices placed on the transverse panels; - remove support elements belonging to the initial structure in the transverse portion; - connect substitute bearing devices to the transverse panels of the shoring structure; and - transfer the load of the structure onto the replacement support devices.

[0029] In one embodiment of the method, the initial structure further comprises a base portion at the lower end of the longitudinal portion, the method further comprising: - make holes through the base portion of the initial structure; - engage foundation elements downwards through the holes; and - form a sole belonging to the shoring structure and connected to the foundation elements, in which the concrete envelope is installed, resting on the sole.

[0030] According to another aspect, there is provided a load-bearing element, comprising an initial structure at a location intended to support a load of a construction work and a shoring structure. The initial structure comprises at least one longitudinal portion between a lower end and an upper end. The shoring structure comprises a concrete shell which supports at least part of the load of the structure instead of the longitudinal portion. The concrete envelope and the longitudinal portion are separated by a gap so that the concrete envelope is not directly stressed in the event of transverse deformation of the longitudinal portion.

[0031] In one embodiment of the load-bearing element, the concrete envelope comprises: - longitudinal panels between the lower end and the upper end of the longitudinal portion of the initial structure; and - ultra-high performance fiber-reinforced concrete, applied around the longitudinal portion, between the longitudinal panels, and forming keying portions connecting the longitudinal panels to each other.

[0032] In one embodiment of the load-bearing element, the longitudinal panels comprise prefabricated sections end to end between the lower end and the upper end of the longitudinal portion of the initial structure.

[0033] In one embodiment of the load-bearing element, the shoring structure further comprises prestressing reinforcements stretched in longitudinal conduits formed in the prefabricated sections of the longitudinal panels.

[0034] In one embodiment of the load-bearing element, the initial structure further comprises a transverse portion extending transversely to the longitudinal portion at the upper end thereof, the transverse portion comprising two opposite main faces, and in which the shoring structure further comprises two transverse concrete panels, arranged parallel to the main faces of the transverse portion, so that the load of the structure is supported by the concrete envelope via the transverse panels.

[0035] In one embodiment of the load-bearing element, the shoring structure further comprises at least one crosspiece securing the two transverse panels of the shoring structure.

[0036] In one embodiment of the load-bearing element, the shoring structure further comprises prestressing reinforcements stretched in longitudinal conduits formed in the concrete envelope and extending into the transverse panels.

[0037] One embodiment of the load-bearing element further comprises support devices secured to the transverse panels of the shoring structure and supporting the load of the structure.

[0038] In one embodiment of the load-bearing element, the initial structure further comprises a base portion at the lower end of the longitudinal portion, bores being formed through the base portion, and wherein the shoring structure further comprises foundation elements engaged downwardly through the drillings, and a sole connected to the foundation elements, the concrete envelope resting on the sole. Brief description of the drawings

[0039] Other characteristics, details and advantages will appear on reading the detailed description below of non-limiting examples of embodiment, and on analyzing the appended drawings, in which: Fig.l

[0040] [Fig.l] is a perspective view of a construction work which can be repaired by a method as proposed herein, in this case a bridge on piers. Fig. 2

[0041] [Fig.2] is a sectional view of an example of a battery repaired by the method. Fig. 3

[0042] [Fig.3] is a perspective view of a battery to be repaired according to another example. Fig. 4

[0043] [Fig.4] is a view similar to [Fig.3] at a first stage of a re preparation. Fig. 5

[0044] [Fig.5] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 6

[0045] [Fig.6] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 7

[0046] [Fig.7] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 8

[0047] [Fig.8] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 9

[0048] [Fig.9] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 10

[0049] [Fig. 10] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 11

[0050] [Fig. 11] is a view similar to [Fig.3] at a later stage of the repair process. Fig. 12

[0051] [Fig. 12] is a view similar to [Fig.3] at a later stage of the repair process. Description of the embodiments

[0052] In the following, the construction element subject to the repair method is a bridge pier. It will be understood that this is a non-limiting example to illustrate the inventive concepts introduced herein and that other construction work configurations can benefit from the invention.

[0053] The pile supports part of the load of the structure. It extends in a longitudinal direction which, in the examples shown, is vertical. The method is also applicable to load-bearing elements whose main direction, in which the loads are transferred to the ground, has a certain inclination relative to the vertical.

[0054] [Fig. 1] is a very schematic representation of a portion of bridge 2 whose deck 8 is supported by piers 4 forming longitudinal portions of an initial supporting structure. Each pier rests on a foundation zone 10 at its lower end and supports a transverse beam 6 at its upper end. The transverse beam 6 itself supports the deck 8 by means of bearing devices 16. The deck 8 is shown here as having structural longitudinal steel beams 14 on which a slab of joists 8 rests.

[0055] The initial structure of the load-bearing element, including a pair of piers 4 and a transverse beam 6 in the example of [Fig.l], may be made of concrete, in whole or in part. This load-bearing element 4, 6 requires repair if it is no longer sufficient to support the self-weight load of the deck 8 and the other service load elements on the bridge, in particular if the concrete has deteriorated, for example due to an RSI phenomenon.

[0056] The repair includes the installation of a shoring structure around the initial failed structure. This shoring structure can be configured so as to preserve the general architecture of the supporting structure of the bridge.

[0057] [Fig.2] shows a concrete shell 20 forming part of the shoring structure and surrounding a pile 4.

[0058] The concrete envelope 20 surrounds the pile 4, leaving a gap 25 between them. Thus, if the pile 4 of the initial structure continues to deteriorate, the gap 25 prevents the concrete envelope 20 of the shoring structure from being disturbed. In particular, any swelling of the pile 4 due to the RSI phenomenon will not induce transverse stresses in the shoring structure. The thickness of the gap 25 is, for example, from one to a few centimeters.

[0059] To optimize the mechanical behavior of the shoring structure, the concrete of the envelope 20 can be an ultra-high-performance fiber-reinforced concrete (UHPFRC, "ultra-high-performance fiber-reinforced concrete").

[0060] In the example of [Fig. 2], the cross-section of the pile 4 is polygonal in shape. The concrete envelope 20 is composed of prefabricated panels 22 arranged along the longitudinal direction of the pile 4 and connected to each other by keying portions 24. The keying portions 24 may also be prefabricated, or made of UHPFRC sprayed on site.

[0061] The prefabricated panels 22 extend over the height of the pile 4. When the latter is relatively long, the panels 22 may consist of longitudinal sections placed end to end and separated by dry joints 26. These joints 26 may be combined to facilitate assembly and improve its stability. To consolidate the concrete envelope 20, the prefabricated panels 22 are crossed by longitudinal conduits 28 in which prestressing cables will be installed. These prestressing cables will be tensioned and anchored to ensure the support and increased mechanical strength of the column formed by the concrete envelope 20.

[0062] The gap 25 provided between the pile 4 and the concrete envelope 20 may be occupied by a flexible material. The flexible materials that can be used include elastomers, expanded polymers such as polystyrene or honeycomb structures, in particular cardboard. The flexible material may be used to provide the gap 25 when the keying portions 24 are made on site by spraying BFUP.

[0063] The shoring structure which replaces or completes the initial structure 4, 6 may comprise other components such as those discussed in the following description of another exemplary embodiment with reference to FIGS. 3 to 12.

[0064] In this other example, a load-bearing element comprises a single pile 4 supporting a transverse beam (or header) 6. [Fig. 3] is a perspective view of the initial structure of the load-bearing element, with pile 4 extending in the longitudinal direction which is here again vertical and beam 6 extending transversely at the upper end of pile 4. At the lower end of pile 4, a base portion 30 (or sole) supports the initial structure of the load-bearing element in the foundation zone 10. In the example shown, base portion 30 has a square cross-section of a larger dimension than the cross-section of pile 4.

[0065] A first step of the repair method consists of making holes 32 in the base portion 30 of the initial structure. Foundation piles 34 are then engaged through the holes 32 and driven into the ground to form a foundation for the shoring structure. The piles 34 are driven to a depth greater than that of the foundation of the initial structure, in order to ensure the independence of the foundation from the shoring structure.

[0066] Then, a concrete sole 36 is formed on the base portion 30 and made integral with the upper part of the foundation piles 34 ([Fig.5]).

[0067] The concrete envelope 20 is installed by resting on the sole 36. The pile 4 is first surrounded by a layer of flexible material (not shown), such as expanded polystyrene. Then, the prefabricated sections forming the panels 22 are placed between the lower end and the upper end of the pile 4 ([Fig.6]), taking care to align the longitudinal conduits 28 which will receive the prestressing cables. The keying portions 24 are then put in place in holding the panels 22 in position ([Fig.7]). The positioning of the keying portions 24 is done for example by spraying BFUP between the panels 22, onto the flexible material surrounding the pile 4, which provides the gap 25 between the pile 4 and the concrete envelope 20 being formed.

[0068] In cases where the failure of the initial supporting structure also concerns the transverse beam 6, the latter can also be reinforced or replaced by the shoring structure.

[0069] The shoring structure comprises for this purpose two transverse panels 40 on either side of the transverse beam 6, which rest on the upper end 35 of the concrete envelope 20. The installation of the transverse panels 40 is illustrated by [Fig. 8]. Each transverse panel 40 is arranged opposite one of the two opposite main faces 38 of the transverse beam 6, parallel to this main face 38. It is also possible to provide a gap between the transverse panel 40 and the main face 38 which faces it, in order to prevent possible deformations of the beam 6.

[0070] Then, crosspieces 42 are installed between the transverse panels 40 and connected to them ([Fig.9]). The crosspieces 42 are made of steel or concrete, for example. They make it possible to secure the transverse panels 40 together to form a header which will replace the transverse beam 6.

[0071] In the embodiment illustrated by [Fig. 10], the conduits 28 formed in the prefabricated sections of the longitudinal panels 22 of the concrete envelope 20 (see also [Fig. 2]) are extended by corresponding conduits formed in the prefabricated elements of the header, in particular the transverse panels 40. The prestressing cables 44 are engaged in these conduits, tensioned and anchored at their two ends by means of anchoring devices 46 shown schematically in [Fig. 10] and arranged, in the lower part, at the level of the sole and, in the upper part, at the level of the transverse panels 40 and / or the crosspieces 42 of the header.The path followed by the prestressing cables 44 will have been determined in advance by a structural calculation so that the shoring structure formed by the sole 36, the concrete envelope 20 and the header 40, 42 has the mechanical properties required with regard to the stresses to which the load-bearing element will be subjected.

[0072] As shown in Figures 8-12, the transverse panels 40 of the header are provided, at their upper part, with brackets 48 added or molded with the UHPFRC of the panels 40 during their prefabrication. The brackets (or corbels) 48 can be placed on the external faces of the transverse panels 40, on the internal faces, or both. In the example shown, there are two brackets 48 on each transverse panel 40. In a following step of the repair method, shown in [Fig. 11], temporary support devices 50 are placed on the brackets 48, such as for example flat jacks.

[0073] The temporary support devices 50 are activated in order to transfer the load of the deck from the support devices 16 of the initial structure to the transverse panels 40 of the header. The support devices 16 of the initial structure are then removed and the support zone where they were installed is demolished. A new support zone secured to the header 40, 42 of the shoring structure is then produced and equipped with replacement support devices 52.

[0074] The substitute bearing devices 52 take over the load of the structure after their installation. The temporary support devices 50 are dismantled and the load-bearing element is then in the state shown in [Fig. 12]. The substitute bearing devices 52 are configured and dimensioned according to the specifications. They can allow certain rotational or sliding movements between the deck and the load-bearing element.

[0075] The shoring structure supplements or replaces the failed initial structure to form a load-bearing element that fulfills the required functions. The load-bearing element may, if desired, retain the same architecture as the initial structure.

[0076] The repair can be carried out without having to install a temporary structure to support the load of the structure. If the use of the structure must remain uninterrupted or almost uninterrupted during the execution of the repair work, this can be achieved with the method presented here.

[0077] The embodiments previously described have been done to provide illustrations of the present invention and are in no way limiting. Various variations may be made to them without departing from the scope of the following claims.

Claims

Claims

1. A method of repairing a construction work, the construction work (2) comprising an initial structure at a location intended to support a load of the work, the initial structure comprising at least one longitudinal portion (4) between a lower end and an upper end, the method comprising: - installing around the longitudinal portion (4) a concrete envelope (20) belonging to a shoring structure so that the concrete envelope (20) supports at least part of the load of the work in place of the longitudinal portion (4), in which a gap (25) is maintained between the concrete envelope (20) and the longitudinal portion (4) so that the concrete envelope (20) is not directly stressed in the event of transverse deformation of the longitudinal portion (4).

2. A method according to claim 1, further comprising: - placing a flexible material around the longitudinal portion (4) before installing the concrete envelope (20), to maintain the gap (25).

3. A method according to any one of the preceding claims, wherein the installation of the concrete envelope (20) comprises: - arranging longitudinal panels (22) between the lower end and the upper end of the longitudinal portion (4) of the initial structure; and - providing concrete around the longitudinal portion, between the longitudinal panels, to form keying portions (24) connecting the longitudinal panels to each other.

4. A method according to claim 3, wherein the concrete supplied between the longitudinal panels (22) is ultra-high performance fiber-reinforced concrete.

5. The method of claim 4, wherein the ultra-high performance fiber-reinforced concrete is sprayed to form the keying portions (24).

6. A method according to claim 5, wherein the ultra-high performance fiber-reinforced concrete is sprayed onto a flexible material placed around the longitudinal portion (4).

7. A method according to any one of claims 3 to 6, wherein the longitudinal panels (22) are formed by placing prefabricated sections end to end between the lower end and the upper end of the longitudinal portion (4) of the initial structure.

8. A method according to claim 7, further comprising: - inserting prestressing reinforcements (44) into longitudinal conduits (28) formed in the prefabricated sections of the longitudinal panels (22); and - tensioning and anchoring the prestressing reinforcements (44).

9. A method according to any one of the preceding claims, wherein the initial structure further comprises a transverse portion (6) extending transversely to the longitudinal portion (4) at the upper end thereof, the transverse portion (6) comprising two opposite main faces (38), the method further comprising: - installing two transverse concrete panels (40), belonging to the shoring structure, parallel to the main faces (38) of the transverse portion (6), so that the load of the structure is supported by the concrete envelope (20) via the transverse panels (6).

10. Method according to claim 9, further comprising: - securing the two transverse panels (40) of the shoring structure by at least one crosspiece (42).

11. A method according to claim 9 or claim 10, further comprising: - inserting prestressing reinforcements (44) into longitudinal conduits (28) formed in the concrete envelope (20) and extending into the transverse panels (40); and - tensioning and anchoring the prestressing reinforcements (44).

12. Method according to any one of claims 9 to 11 further comprising: - transferring the load of the structure onto temporary support devices (50) arranged on the transverse panels (40); - removing support elements (16) belonging to the initial structure in the transverse portion (6); - securing replacement support devices (52) to the transverse panels (40) of the shoring structure; and - transferring the load of the structure onto the replacement support devices (52).

13. A method according to any preceding claim, wherein the initial structure further comprises a base portion (30) at the lower end of the longitudinal portion (4), the method further comprising: - making holes (32) through the base portion (30) of the initial structure; - engaging foundation elements (34) downwards through the holes (32); and - forming a sole (36) belonging to the shoring structure and connected to the foundation elements (34), in which the concrete envelope (20) is installed by bearing on the sole (36).

14. A load-bearing element, comprising an initial structure at a location intended to support a load of a construction work (2) and a shoring structure, wherein the initial structure comprises at least one longitudinal portion (4) between a lower end and an upper end, wherein the shoring structure comprises a concrete envelope (20) supporting at least part of the load of the work in place of the longitudinal portion (4) wherein the concrete envelope (20) and the longitudinal portion (4) are separated by a gap (25) so that the concrete envelope (20) is not directly stressed in the event of transverse deformation of the longitudinal portion (4).

15. A load-bearing element according to claim 14, further comprising a flexible material placed in the gap (25) between the concrete shell (20) and the longitudinal portion (4).

16. A load-bearing element according to claim 14 or claim 15, wherein the concrete envelope (20) comprises: - longitudinal panels (22) between the lower end and the upper end of the longitudinal portion (4) of the initial structure; and - ultra-high performance fiber-reinforced concrete, provided around the longitudinal portion (4), between the longitudinal panels (22), and forming keying portions (24) connecting the longitudinal panels to each other.

17. Load-bearing element according to claim 16, in which the longitudinal panels (22) comprise prefabricated sections end to end between the lower end and the upper end of the longitudinal portion (4) of the initial structure.

18. A load-bearing element according to claim 17, wherein the shoring structure further comprises prestressing reinforcements (44) tensioned in longitudinal conduits (28) formed in the prefabricated sections of longitudinal panels (22).

19. A load-bearing element according to any one of claims 14 to 18, wherein the initial structure further comprises a transverse portion (6) extending transversely to the longitudinal portion (4) at the upper end thereof, the transverse portion (6) comprising two opposite main faces (38), and wherein the shoring structure further comprises two transverse concrete panels (40), arranged parallel to the main faces of the transverse portion (6) so that the load of the structure is supported by the concrete envelope (20) via the transverse panels (40).

20. A load-bearing element according to claim 19, wherein the shoring structure further comprises at least one cross member (42) securing the two transverse panels (40) of the shoring structure.

21. A method according to claim 19 or claim 20, wherein the shoring structure further comprises prestressing reinforcements (44) tensioned in longitudinal conduits (28) formed in the concrete envelope (20) and extending into the transverse panels (40).

22. Load-bearing element according to any one of claims 19 to 21, further comprising support devices (52) integral with the transverse panels (40) of the shoring structure and supporting the load of the structure.

23. A load-bearing element according to any one of claims 14 to 22, wherein the initial structure further comprises a base portion (30) at the lower end of the longitudinal portion (4), bores (32) being formed through the base portion, and wherein the shoring structure further comprises foundation elements (34) engaged downwardly through the bores (32), and a sole plate (36) connected to the foundation elements (34), the concrete shell (20) bearing on the sole plate (36).

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