Extendable modular foundation and building method

Abstract

The present invention relates to an extendable modular foundation with one or more foundation layers (or modules), each one larger than the previous one, superimposed on a base footing, which already exists or is newly built. The layers are only connected at their central portion by means of fastening bolts and extensions, operating structurally as a laminar foundation, consisting of the outermost foundation layer, combined with a bottom counterweight consisting of the previous layers and the base footing. The invention is very effective at supporting the necessary stresses in high-rise elements, allowing successive foundation layers to be built on existing layers. It is a modular structure designed to be extended from its inception and to evolve over time by adding more layers depending on future requirements without being detrimental to the initial investment. It additionally prevents the modification of the base footing, thereby reducing building time and economic cost, while generating a lot less waste in line with "Zero Waste" sustainability goals.

Description

[0001] Expandable modular foundation and construction procedure

[0002] This specification refers, as its title indicates, to an expandable modular foundation, usable in wind turbine farms, both for metallic, hybrid or concrete towers, as well as in communications towers, lighting towers, bridge and viaduct piers, etc., which comprises one or more foundation layers, each one of greater extension than the previous one, superimposed on the base footing of the initial phase, joined only in their central part to the anchor bolts of the base footing by means of extensions, which behaves like a laminar foundation, constituted by the most external foundation layer, combined with a lower counterweight constituted by the previous layers and the base footing, allowing great effectiveness to withstand the necessary efforts in a tower or pier of great height, being able to build successive layers of foundation, in a modular manner, on the previously existing phases.This expansion capacity also makes it ideal for use in wind farm repowering processes.

[0003] Field of the invention

[0004] The invention relates to the field of footings or foundations for towers, piles or vertical elements, especially for wind turbine towers.

[0005] Current state of the art

[0006] In the foundation design process, there are circumstances in which it is known that in the near future it will be necessary to expand the foundation capacity. This is the case for bridges, due to increased traffic capacity or increased traffic loads; in the case of wind turbines, due to increased wind turbine capacity due to increased power and / or increased tower height. This fact results in the need to increase the size of the foundation, assuming, for an already constructed element, an extension or allowing for the establishment of an expandable modular construction strategy in order to avoid penalizing the initial investment with oversizing.For example, in the case of bridge piers or viaducts where some ground failure occurs, to compensate for design errors, to increase the size of poles or communication towers, or, in the case of wind turbine farms, to carry out an expansion or repowering process, also known as "repowering," which involves replacing the wind turbines with others with greater production capacity, greater height, and therefore with greater extension and greater foundation requirements. In the case of wind turbine farms, this is a fairly common situation due to the need to repower existing wind farms, replacing them with more modern models, with new technologies, more powerful and with greater energy production and larger size, which require larger foundations to withstand greater stresses.

[0007] In all these cases, we face the problem of an existing foundation and the need to build a new one with greater capacity. There are several ways to address this problem, always starting from an existing foundation but never as an expandable modular element. The most common approach is to excavate the previous foundation, demolish it, remove the remains, and build the new, larger foundation in its place. This is a long, expensive process that generates a large amount of construction waste that must be disposed of.

[0008] In many cases, this procedure is so tremendously expensive and time-consuming that wind turbines were often installed elsewhere, wasting the existing site and causing significant environmental impact. Obviously, this wouldn't apply to bridge piers or viaducts.

[0009] To solve this and take advantage of the previous foundation, there are known procedures, such as those described in patents ES-2493722 "Process for executing a wind turbine to repower an existing wind farm and wind turbine obtained", KR20190101219 "Wind turbine Re-powering Foundation structures" and KR20200057954 "Wind turbine structure for retrofitting spread footing in partial repowering and construction method for the same”, which carry out a large excavation around the pre-existing foundation, and carry out a new foundation around and above it, using conventional techniques, obtaining a new larger foundation. This presents many drawbacks, mainly due to the large excavations and earthworks required, as well as the need to use a large amount of both concrete and metal reinforcement or rebar, in addition to a high section.Connecting this reinforcement to the existing foundation is highly manual, slow, and expensive to execute, with questionable quality assurance. All of this entails significant financial costs and a long construction time. Adding to these problems is the fact that, for proper setting, concreting must be done continuously, without interruptions, requiring a stable supply of a high volume of concrete, which is difficult or impossible to achieve in many regions or countries. Extreme temperature conditions—both cold and hot, for example, in desert areas—complicate concrete setting because it is a chemical reaction, and many optimal wind farms are located in forests or semi-deserts due to the strong thermal winds.

[0010] Another additional problem is that the necessary excavation requires ramps for the lowering of heavy machinery, which increases work time. The bottom of the excavation also needs to be leveled and smoothed.

[0011] All of this means that the typical time for excavation, preparation, concreting, and setting takes several weeks, which, when multiplied by the large number of wind turbines in each park, results in very high financial costs.

[0012] There are some types of foundations that solve some of the problems mentioned above of large excavations, high volume of concrete and reinforcement, such as the one described in ES2764468 “Foundation for wind towers”, which proposes the use of prefabricated concrete beams combined with small footings, these beams being structurally related in the central part of the foundation by means of joining and support elements of the tower, but it presents the problem that it is not planned or possible to build on an existing foundation, nor its reuse, and it also has the disadvantage of requiring in some cases a structure with ballast or weight functions, made in situ with concrete in the area where the beams are joined.

[0013] There are also foundations that overcome these problems by taking advantage of the existing foundation, as described in ES2894337 "Procedure for extending foundations in wind farms" which uses a structure of beams superimposed on the existing foundation and joined to it, supported by new peripheral foundations of a smaller size, forming a new foundation suitable for a larger structure, but it also presents a considerable construction complexity and requires the transport of large prefabricated beams. There is also some solution, such as the one described in ES2493722 "Procedure for the execution of an existing wind turbine and a wind turbine obtained to repower a wind farm" which takes advantage of the existing foundation to merge it with the new foundation, creating a new foundation completely joined to the previous foundation, forming a unit circumscribed to the previous foundation and integral with it, at the same elevation.Since both foundations, the new and the existing, need to be completely joined together, it is necessary to carry out considerable drilling or partial demolition of the old foundation in order to implement the means of joining them with the new one. This also generates waste. And, since they are at the same level, the large amount of earth removed in the necessary excavation must be taken to another site, generating environmental impact problems.

[0014] There are also known foundation re-growth techniques, such as the one described in patent CN114753403A "Foundation structure for replacing small wind turbine generator with large wind turbine generator and construction method" for the re-growth of wind turbine farms by re-growing the footing, as in the previous case, constructing a new footing structurally joined at the reinforcement level with the previous footing, but this requires chiseling work on the concrete from the surface of the previous footing, removing its outer layer and extracting the remains until uncovering the ends of the internal reinforcement, which must then be joined to the new reinforcement for the extension. It is a costly process, in which a single monolithic footing is obtained, resulting from the union of the existing previous foundation with the new foundation constructed by joining the two reinforcements. In this foundation, the previous footing is a structural part of the new one.

[0015] Description of the invention

[0016] To solve the current problem of foundation expansion, the expandable modular foundation object of the present invention has been devised, which comprises

[0017] - a base footing, constructed in a first phase or existing, containing at least one conventional foundation made by any conventional method, equipped with anchor bolts for a tower, the reference to tower in this specification being extrapolated to any type of vertical construction that can be erected on a footing type foundation, - one or more foundation layers, preferably with a truncated cone structure, each one extending greater than the previous one, superimposed, one on top of the other, on the base footing, at a higher level, each one equipped with bolts for anchoring a tower on the last foundation layer constructed and reusable for connection with subsequent foundation layers,

[0018] - a plurality of extensions of the anchor bolts of the previous layer constructed up to the upper level of the new phase under construction, the anchor bolts being distributed diametrically around a larger diameter in each layer, to allow the anchoring of towers of larger diameter or structural elements of greater capacity, each successive layer of foundation being mechanically joined, by means of conventional extensions of the bolts, exclusively with the footing module of the immediately preceding foundation layer, the outermost foundation layer being the support of the tower, or of a structural element of greater capacity, by means of its own anchor bolts for this purpose and being mainly responsible for its stability as a laminar foundation, and the interior modules of previous phases being mainly responsible for acting as a counterweight.

[0019] Considering each foundation layer as a module, the foundation behaves like a shell foundation, consisting of the outermost foundation module, combined with a lower counterweight consisting of the base footing and the previously constructed inner modules. This modular structure, based on superimposed layers, allows for expansion in subsequent phases simply by adding a new module, or foundation layer, on top of the previous ones.

[0020] The modular foundation can be built on previously constructed foundation layers as an extension, on an existing conventional constructed footing, or designed as a modular structure that can be expanded from the ground up.

[0021] Each layer of the foundation can be constructed at intervals that are determined by the evolving needs of the element it supports, such as a wind turbine farm, viaduct, etc., such as an increase in size, height, stresses, etc. The different layers of the foundation can be concreted in situ or, alternatively, be made up of prefabricated reinforced and / or prestressed concrete elements joined together. Both technologies can be combined in different layers.

[0022] Preferably, most of the outermost foundation layer will be covered with earth, with only the central portion coinciding with the base of the tower emerging, thus minimizing the visual impact.

[0023] This expandable modular foundation involves a characteristic construction procedure that includes,

[0024] - an optional preliminary phase of initial construction of the structure,

[0025] - a phase of removal of the existing tower.

[0026] - a phase of removal of fillings until the existing footing is uncovered and excavation of the accommodation for the new modular foundation layer around said existing footing, considering the existing footing to be the one that previously supported the tower, which may be the base footing, or the base footing plus one or several modular foundation layers resulting from previous processes,

[0027] - a cleaning phase of the upper surface of the existing footing,

[0028] - a phase of installing the extensions on the existing outermost anchor bolts, where the existing tower was previously anchored,

[0029] - a phase of construction of the new foundation layer,

[0030] - a phase of filling the remaining housing using the earth extracted during the excavation of the housing in the second phase, and compacting it leaving the central part of the new foundation layer and the upper ends of the new anchor bolts accessible,

[0031] - a tightening phase of the connecting bolts between the new module and the immediately preceding one, and

[0032] - a phase of placing the new tower, securing it to the new anchor bolts using conventional mechanical means.

[0033] The optional preliminary phase of initial construction of the structure includes:

[0034] - a stage of construction of the base footing, equipped with anchor bolts for a tower,

[0035] - a stage of placing the tower and

[0036] - an infrastructure operation phase. The construction phase of the new foundation layer includes, preferably with in-situ concreting,

[0037] - a stage of placing the reinforcement of the armour for the new module,

[0038] - a stage of fitting the new bolt cage of the new module

[0039] - a concreting stage, and

[0040] - a concrete setting stage.

[0041] The construction phase of the new foundation layer includes, in an alternative implementation with prefabricated concrete elements,

[0042] - a stage of placement of the prefabricated parts that make up the new foundation layer, with the new bolt cage incorporated,

[0043] - a stage of execution of the connection between the prefabricated elements, by mechanical means or by concreting concrete joints with passive reinforcement.

[0044] These phases will be carried out sequentially. Except for the optional preliminary phase of initial structural construction, all phases can be repeated as many times as necessary to create new modules or foundation layers on top of existing ones, each time it is necessary to expand the tower to a larger one with greater foundation requirements. Each time, a new, larger exterior foundation layer is created, evolving in parallel with the towers' support needs.

[0045] Likewise, foundation modules constructed with in-situ concrete can be combined with foundation modules constructed with prefabricated concrete elements in any order, depending on need or availability.

[0046] The preferred use of this expandable modular foundation is as a support for towers, more preferably as a support or integral part of a wind turbine, and even more preferable when the wind turbine towers are part of an expansion or repowering process, also known as "repowering," of the wind turbine farm. This involves replacing the wind turbines with others with greater production capacity, greater height, and therefore with greater extension and greater foundation requirements. Obviously, it can be used for any type of tower, whether steel, concrete, or mixed, and for wind turbines as well as for communications, lighting, poles, bridge piers, or viaducts, etc.

[0047] Advantages of the invention

[0048] This expandable modular foundation presented here offers multiple advantages over currently available foundations, the most important of which is that it works structurally as a laminar foundation, consisting of the outermost foundation layer, combined with a lower counterweight made up of the previous layers, allowing great effectiveness in supporting the necessary forces in a tower or high-rise pile.

[0049] It is worth highlighting the advantage that the design phase can consider and anticipate the future use of extensions, minimizing future expansion costs and reducing the initial investment by avoiding oversizing. It is a process that can be expanded and modular from the structural conception, allowing the foundation to be conceived as an expandable structure from the outset, enabling subsequent adaptations or extensions, including retrofitting. This evolution is possible due to its modular structure, which allows for expansion in subsequent phases by superimposing layers on top of previous ones.

[0050] Another important advantage is that the foundation layer or layers are superimposed on the existing foundation at a higher level, avoiding the need to demolish and remove the old foundations, thereby saving both time and money. It is important to note that the new foundation layer and the existing foundation are only connected in the central area by mechanical connections, with the existing foundation acting as ballast.

[0051] It is also important to note that, unlike existing foundations, this expandable modular foundation requires no intervention on the existing foundation, as it is not chiseled, drilled, or modified in any way; it is simply joined using existing bolts and threaded extensions. As a result, no waste from the previous foundation is generated that needs to be transported and disposed of in a landfill, resulting in a faster and more environmentally friendly process, aligned with the sustainability goal of "Zero Waste."It should also be noted that the inner reinforcement of the new foundation is not connected to the inner reinforcement of the existing footing, and is independent of the existing footing. The existing footing is not an integral part of the new foundation and does not provide support, but is used solely as a counterweight, being connected exclusively in its central section by means of conventional bolt extensions.

[0052] Another advantage worth highlighting is that this foundation requires minimal excavation, much less than with other existing foundation techniques. This means less earthworks are required. Furthermore, the removed soil is reused to cover the new foundation layer, resulting in almost zero environmental impact.

[0053] It should be noted that this expandable modular foundation is especially useful in the expansion or upgrading of wind turbine farms, which involves replacing existing wind turbines with others with greater production capacity, greater height, and therefore greater extension and greater foundation requirements.

[0054] Another of the most important advantages worth highlighting is that it is an evolutionary modular foundation, since the set of phases can be repeated as many times as necessary to create new foundation layers when greater foundation requirements arise due to tower expansion. Each time, a larger outer foundation layer is created, evolving in parallel with the towers' support requirements and therefore being applicable and easily adaptable to future support needs. Since successive foundation layers can be built on top of existing ones, the foundation's capacity can be successively increased.

[0055] It is also important to note that, since it can be used for any type of tower, whether metallic, concrete, or mixed, and for wind turbines, communications, lighting, poles, bridge or viaduct piers, etc., it opens up a wide range of application possibilities both in construction and in the repair and maintenance of existing facilities. Description of the figures

[0056] In order to better understand the object of the present invention, a practical embodiment of a wide modular foundation is shown in the attached drawing.

[0057] In this plan, figure -1- shows a perspective section view of a foundation with two layers and the expandable modular foundation base footing.

[0058] Figure -2- shows a sectioned side view of a foundation from an optional preliminary phase of initial construction of the structure.

[0059] Figure -3- shows a sectioned side view of an expandable modular foundation consisting of a layer on the base footing, with an enlarged detail showing the anchor bolts and the extensions of the anchor bolts of the lower foundation.

[0060] Figure -4- shows a sectioned side view of an expandable modular foundation consisting of two layers on the base footing.

[0061] Figure -5- shows a sectioned side view of a base footing with the existing tower mounted, from the optional preliminary phase of initial construction of the structure.

[0062] Figure -6- shows a sectioned side view of the base footing with the existing tower already dismantled, after the removal stage of the existing tower.

[0063] Figure -7- shows a sectioned side view of the foundation after the backfill removal phase until the existing footing is uncovered and the housing excavated.

[0064] Figure 8 shows a sectional side view of the foundation after the first step of the fourth phase of placement of the new anchor bolt cage, the extensions of the existing anchor bolts, and the reinforcing bar, in the preferred embodiment with in-situ concreting. Figure 9 shows a sectional side view of the foundation after the installation phase of the extensions on the anchor bolts and the construction phase of the new foundation layer, in the preferred embodiment with in-situ concreting.

[0065] Figure -10- shows a sectioned side view of the foundation after the placement phase of the new tower.

[0066] Preferred embodiment of the invention

[0067] The constitution and characteristics of the invention may be better understood with the following description made with reference to the attached figures.

[0068] As can be seen in figures 1, 2, 3 and 4, it is illustrated how the expandable modular foundation comprises

[0069] - a base footing (2), containing at least one conventional foundation made by any conventional method, constructed in a preliminary or existing phase, equipped with anchor bolts (3) for a tower (6), the reference to tower in this specification being extrapolated to any type of vertical construction that can be erected on a footing type foundation,

[0070] - one or more foundation layers (1a, 1b), preferably with a truncated cone structure, each one extending greater than the previous one, superimposed, one on top of the other, on the base footing (2), at a higher level, each one provided with anchor bolts (5) for a tower (6) on the last foundation layer (1a, 1b) built and reusable for connection with the subsequent foundation layers (1a, 1b),

[0071] - a plurality of extensions (4) of the anchor bolts (3,5) of the previous layer constructed up to the upper level of the new phase under construction, located below the outermost foundation layer (1a, 1b) to equalize its height with that of the anchor bolts (5) of said outermost foundation layer (1a, 1b), the anchor bolts (3,5) being distributed diametrically around a larger diameter in each layer, to allow the anchoring of towers of larger diameter or larger structural elements, each successive foundation layer (1a, 1b) being mechanically connected, by means of extensions (4) of the anchor bolts (3,5), exclusively to the immediately lower foundation layer (1a, 1b), or to the base footing (2) in the case of being the first foundation layer (1a), the outermost foundation layer (1b) being the support of the tower or a structural element larger in size,by means of its own anchor bolts (5) for this purpose and mainly responsible for its stability as a laminar foundation, and the interior modules (1a, 2) from previous phases being responsible for acting mainly as a counterweight.

[0072] The base footing (2) may be a conventional foundation made by any conventional method, or be the initial phase of an expandable modular foundation conceived as such.

[0073] Considering each of the foundation layers as a module, the foundation behaves as a laminar foundation, consisting of the outermost foundation module (1b), combined with a lower counterweight consisting of the base footing (2) and the previously made inner modules (1a). This modular structure, based on superimposed foundation layers (1a, 1b), allows for expansion in subsequent phases by simply adding a new module, or foundation layer, superimposed on the previous ones.

[0074] The modular foundation can be built on previously constructed foundation layers (1a, 1b) as an extension, or on an existing conventional base footing (2), or be the initial phase of an expandable modular foundation conceived as such. Each layer of the foundation (1a, 1b) can be built with the separation in time that marks the evolutionary needs of the element they support, wind turbine farm, viaduct... etc., such as increase in size, height, forces... etc.

[0075] The different foundation layers (1a, 1b) can be concreted in situ, or alternatively be made up of prefabricated reinforced and / or prestressed concrete elements joined together, both technologies being able to be combined in different layers.

[0076] Preferably, the majority of the outermost foundation layer will be covered with a fill (7) of earth, or other elements, with only the central part coinciding with the base of the tower emerging, thus minimizing the visual impact.

[0077] This foundation involves a characteristic construction procedure, as illustrated in figures 5, 6, 7, 8, 9 and 10, which includes

[0078] - an optional preliminary phase of initial construction of the structure,

[0079] - a phase of removal of the existing tower (6). - a phase of removal of the fill (7) until the existing footing is uncovered and excavation of the housing (9) for the new modular foundation module (1a, 1b) around said existing footing, considering as the existing footing the one that previously supported the tower (6), which may be the base footing (2), or the base footing (2) plus one or several layers of modular foundation (1a, 1b...) resulting from previous processes,

[0080] - a cleaning phase of the upper surface (10) of the existing footing,

[0081] - an installation phase of the extensions (4) on the existing outermost anchor bolts (3,5), where the existing tower (6) was previously anchored,

[0082] - a phase of construction of the new foundation layer (1a, 1 b),

[0083] - a filling phase (7) of the remaining housing using the soil previously extracted in the excavation of the housing (9), and its compaction leaving the central part of the new foundation layer (1a) and the upper ends of the new anchor bolts (5) accessible,

[0084] - a tightening phase of the extensions (4) that make up the connecting bolts between the new foundation layer (1 b) and the immediately preceding layer (1a), or between the new foundation layer (1a) and the base footing (2) in the case of being the first module, by means of conventional mechanical means (8), and

[0085] - a phase of placing the new tower (6), securing it on the new anchor bolts (5) by conventional mechanical means (8).

[0086] The optional preliminary phase of initial construction of the structure includes:

[0087] - a stage of construction of the base footing (2), provided with anchor bolts (3) for a tower,

[0088] - a stage of placing the tower (6) and

[0089] - a stage of exploitation of the infrastructure.

[0090] This optional preliminary phase of initial construction of the structure may have been carried out at a much earlier time and any known and possible technology for the different stages that comprise it.

[0091] The construction phase of the new foundation layer (1a, 1 b) comprises, in a preferred embodiment with in-situ concreting,

[0092] - a stage of laying the reinforcement of the armour (11),

[0093] - a stage of fitting the new anchor bolt cage (5),

[0094] - a concreting stage of the new foundation layer (1a, 1 b), and - a setting stage of the concrete.

[0095] The construction phase of the new foundation layer (1a, 1b) comprises, in an alternative embodiment with prefabricated concrete elements,

[0096] - a stage of placement of the prefabricated parts that make up the new foundation layer (1a, 1b), with the new anchor bolt cage (5) incorporated,

[0097] - a stage of execution of the connection between the prefabricated elements, by mechanical means or by concreting concrete joints with passive reinforcement.

[0098] These phases will be carried out sequentially. Except for the optional preliminary phase of initial structural construction, all phases can be repeated as many times as necessary to create new foundation modules on top of existing ones, each time it is necessary to expand the tower to a larger one with greater foundation requirements. Each time, a larger external foundation module is created, evolving in parallel with the towers' support needs.

[0099] This modular structure defined by an overlapping of foundation layers (1a, 1b) can also be realized by combining foundation layers (1a, 1b) constructed with in-situ concrete, with foundation layers (1a, 1b) constructed with prefabricated concrete elements in any order, according to need or availability.

[0100] The preferred use of this expandable modular foundation is as a support for towers, more preferably as a support or integral part of a wind turbine, and even more preferable when the wind turbine towers are part of an expansion or repowering process, also known as "repowering," of the wind turbine farm. This involves replacing the wind turbines with others with greater production capacity, greater height, and therefore with greater extension and greater foundation requirements. Obviously, it can be used for any type of tower, whether steel, concrete, or mixed, and for wind turbines as well as for communications, lighting, poles, bridge piers, or viaducts, etc.

[0101] A person skilled in the art will readily understand that features of different embodiments can be combined with features of other possible embodiments, provided that such a combination is technically possible. All information relating to examples or embodiments forms part of the description of the invention.

Claims

CLAIMS 1 - Expandable modular foundation, characterized by comprising - a base footing (2), containing at least one conventional foundation made by any conventional method, constructed in a preliminary or existing phase, provided with anchor bolts (3) for a tower (6), - one or more foundation layers (1a, 1b), each one extending greater than the previous one, superimposed, one on top of the other, on the base footing (2), at a higher level, each one provided with anchor bolts (5) for a tower (6) on the last foundation layer (1a, 1b) constructed and reusable for connection with the subsequent foundation layers (1a, 1b), - a plurality of extensions (4) of the anchor bolts (3,5) of the previous foundation layer constructed up to the upper level of the new phase under construction, located below the outermost foundation layer (1a, 1b) to equalize its height with that of the anchor bolts (5) of said outermost foundation layer (1a, 1b), the anchor bolts (3,5) being distributed with a greater extension in each layer depending on the height, each successive foundation layer (1a, 1b) being mechanically connected, by means of extensions (4) of the anchor bolts (3,5), exclusively to the immediately lower foundation layer (1a, 1b), or to the base footing (2) in the case of being the first foundation layer (1a), the outermost foundation layer (1b) being the support of the tower or a larger structural element, by means of its own anchor bolts (5) to this effect. 2 - Expandable modular foundation, according to the previous claim, characterized in that each modular foundation layer (1a, 1b) is made up of prefabricated reinforced or prestressed concrete elements, joined together. 3 - Expandable modular foundation, according to claim 1, characterized in that each modular foundation layer (1a, 1b) is concreted in situ. 4 - Expandable modular foundation, according to any of the preceding claims, characterized in that the base footing (2) is a conventional foundation with one or more modular foundation layers (1a, 1b) on it. 5 - Expandable modular foundation, according to any of the previous claims, characterized in that the majority of the outermost modular foundation layer (1a, 1b) is covered with an earth filling (7), with only the central part coinciding with the base of the tower emerging. 6 - Expandable modular foundation, according to any of the preceding claims, characterized in that the modular foundation layers (1a, 1b) adopt a truncated conical structure. 7 - Method for constructing an expandable modular foundation, according to any of the preceding claims, characterized in that it comprises - an optional preliminary phase of initial construction of the structure, - a phase of withdrawal of the existing tower (6). - a phase of removal of the fill (7) until the existing footing is discovered and excavation of the housing (9) for the new modular foundation module (1a, 1 b) around said existing footing, considering as the existing footing the one that previously supported the tower (6), which may be the base footing (2), or the base footing (2) plus one or several layers of modular foundation (1a, 1b...) resulting from previous processes, - a cleaning phase of the upper surface (10) of the existing footing, - an installation phase of the extensions (4) on the existing outermost anchor bolts (3), where the existing tower (6) was previously anchored, - a phase of construction of the new foundation layer (1a, 1b), - a filling phase (7) of the remaining housing using the soil previously extracted in the excavation of the housing (9), and its compaction leaving the central part of the new foundation layer (1a) and the upper ends of the new anchor bolts (5) accessible, - a tightening phase of the extensions (4) that make up the connecting bolts between the new foundation layer (1 b) and the immediately preceding layer (1a), or between the new foundation layer (1a) and the base footing (2) in the case of being the first module, by means of conventional mechanical means (8), and - a phase of placing the new tower (6), securing it on the new anchor bolts (5) by conventional mechanical means (8). 8 - Method for constructing an expandable modular foundation, according to claim 7, characterized in that the optional preliminary phase of initial construction of the structure comprises - a stage of construction of the base footing (2), provided with anchor bolts (3) for a tower, - a stage of placing the tower (6) and - a stage of exploitation of the infrastructure. 9 - Method for constructing a wide modular foundation, according to claim 7, characterized in that the phase of creating the new foundation layer (1a, 1b) comprises - a stage of laying the reinforcement of the armour (11), - a stage of fitting the new anchor bolt cage (5), - a concreting stage of the new foundation layer (1a, 1 b), and - a concrete setting stage. 10 - Method for constructing an expandable modular foundation, according to claim 7, characterized in that the phase of creating the new foundation layer (1a, 1 b) comprises - a stage of placement of the prefabricated parts that make up the new foundation layer (1a, 1b), with the new anchor bolt cage (5) incorporated, and - a stage of execution of the connection between the prefabricated elements, by mechanical means or by concreting concrete joints with passive reinforcement. 11 - Method for constructing an expandable modular foundation, according to claim 7, characterized in that all the phases, except for the optional preliminary phase of initial construction of the structure, can be repeated as many times as necessary to create new foundation layers each time it is necessary to expand the tower due to one of larger dimensions and greater foundation requirements. 12 - Use of an expandable modular foundation, according to any of the preceding claims, characterized in that the foundation serves as a support for towers. 13 - Use of an expandable modular foundation, according to claim 12, characterized in that the towers are a support or integral part of a wind turbine. 14 - Use of an expandable modular foundation, according to claim 12, characterized in that the wind turbine towers are part of a repowering process of the wind turbine park.

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