MODULAR PRECAST FOUNDATIONS FOR TRANSMISSION TOWERS

TECHNICAL FIELD

[0001] The present subject matter relates, in general, to the field of power transmission and, particularly but not exclusively, to a power transmission tower.

BACKGROUND

[0002] Electric power transmission involves the bulk transfer of high-voltage electricity from power plants generating the electric power to electrical substations where voltage is transformed and distributed to consumers or other substations. Electric power transmission requires a dedicated infrastructure that can act as an expressway for transmitting high-voltage electricity over long distances. The power transmission infrastructure, inter alia, comprises transmission cables and transmission towers to support such cables.

[0003] A transmission tower is a tall structure that is generally made from steel to support heavy overhead conductors, lightning conductors, and other accessories necessary for the bulk transfer of high-voltage electricity at a sufficiently safe height from the ground. The shape, height, and sturdiness of the transmission towers are designed depending on the stresses to which they are to be exposed.

[0004] Transmission towers form an important structural member of the power transmission infrastructure. The configuration of a transmission tower directly affects not only the construction speed, economic efficiency, ease of installation, maintenance, and repair of the transmission tower but also the reliability of the power transmission infrastructure.

SUMMARY OF THE INVENTION

[0005] The present invention is aimed at facing at least some of the above issues, and in particular at providing an easy-to-assemble precast foundation.

[0006] This is achieved by a precast foundation assembly that comprises a bottom foundation section including a plurality of bottom slabs, each of the plurality of bottom slabs being connected to adjoining bottom slabs to form a flat top surface. The top surface formed by the plurality of bottom slabs comprises a plurality of upwardly protruding secondary dowel bars. The precast foundation assembly further comprises a top foundation section comprising one or more top slabs, wherein each of the one or more top slabs comprises a plurality of secondary sleeves disposed on a bottom surface of each of the one or more top slabs. To assemble the top foundation section on the bottom foundation section, each of the plurality of secondary sleeves is to accommodate a corresponding secondary dowel bar. A top surface of one of the one or more top slabs comprises a plurality of tertiary dowel bars. The precast foundation assembly also comprises a chimney section that is to be disposed atop the top foundation section. The chimney section comprising a plurality of second grout couplers having outwardly protruding first grooves located at a bottom portion of the chimney section. Each of the first grooves is to receive a corresponding tertiary dowel bar when erecting the chimney section atop the top foundation section.

[0007] In addition to the embodiments described herein, the precast foundation assembly in the present invention may encompass various alternate configurations and arrangements. For example, in one configuration, the precast foundation assembly may comprise the bottom foundation section including a single bottom slab or two bottom slabs, the top foundation section with two top slabs, and one chimney section. In another configuration of the precast foundation assembly, the top foundation section and the chimney section may be integrated into a singular unit forming a unified assembly. In yet another configuration, the top foundation section may be omitted from the precast foundation assembly, providing flexibility in the structural layout.

[0008] the top foundation section may combine with the chimney section as a unified unit or maybe a standalone unit without the top foundation section, providing adaptability in assembly design. In another configuration,

[0009] According to other aspects and possible embodiments, the precast foundation assembly according to the present invention comprises one or more of the following characteristics taken individually or in any possible combination:

- each of the plurality of bottom slabs is a separate precast concrete unit;

- each of the plurality of bottom slabs have a length in a range of 1 - 9 meters and a width in a range of 1 - 4 meters;

- a first bottom slab and a second bottom slab of the plurality of bottom slabs comprising first primary dowel bars and second primary dowel bars, respectively, are located diagonally opposite to each other, and a third bottom slab and a fourth bottom slab of the plurality of bottom slabs comprising first primary sleeves and second primary sleeves, respectively, are located diagonally opposite to each other,

wherein the first primary dowel bars and the second primary dowel bars are disposed on two consecutive edges of the first bottom slab and the second bottom slab, respectively, interfacing with edges of the third bottom slab and fourth bottom slab, respectively, the first primary sleeves and the second primary sleeves being disposed on the edges of the third bottom slab and fourth bottom slab interfacing with the first bottom slab and the second bottom slab,

wherein, to form a connection between each of the plurality of bottom slabs within the bottom foundation section, the first primary dowel bars are inserted into the corresponding first primary sleeves, and the second primary dowel bars are inserted into the corresponding second primary sleeves;

- the first primary dowel bars are disposed within a first overlap extension extending from a periphery of the first bottom slab along a first and second consecutive edge of the first bottom slab, and the second primary dowel

bars are disposed within a second overlap extension extending from a periphery of the second bottom slab along a first and second consecutive edge of the second bottom slab,

wherein each of the first overlap extension and the second overlap extension has a reduced thickness compared to the rest of the first bottom slab and the second bottom slab, respectively, the reduced thickness being such that a combined thickness of the first overlap extension and the second overlap extension in an overlap region of the plurality of bottom slabs is substantially same as the rest of the slab, and when joined together, the first overlap extension and the second overlap extension align with the corresponding first primary sleeves, and the second primary sleeves on the adjacent slabs, to accommodate the dowel bars within the sleeves;

- the third bottom slab comprises a first recess formed across a merging line of the first edge and the second edge of the third bottom slab, and the fourth bottom slab comprises a second recess formed across a merging line of the first and second edge of the fourth bottom slab, wherein, when joining the plurality of bottom slabs to form the bottom foundation section, the first overlap extension extends into the respective first recess, and the second overlap extension extends into the respective second recess;

- a cover plate of predefined thickness, the cover plate being positioned over the top surface of the bottom foundation section once the plurality of bottom slabs are joined together;

- a first top slab of the one or more top slabs includes a first projection extending horizontally outward on one side and a second top slab of the one or more top slabs includes a second projection extending horizontally outward on a side opposite to the first projection, wherein the first projection and the second projection together form a third recess and a fourth recess on the top surface of the top two slabs;

- the first projection of the first top slab includes a plurality of first horizontal dowel bars protruding horizontally outward, and the fourth recess of the second top slab includes a plurality of second horizontal dowel bars to align with the first horizontal dowel bars of the first top slab;

- the first top slab further includes a plurality of horizontal sleeves open from the top, each adapted to receive a first horizontal dowel bar disposed on the first projection;

- the first top slab and the second top slab have an asymmetrical surface area, and the plurality of tertiary dowel bars is disposed on the top slab having a larger surface area;

- a first grout coupler is used to reinforce each of the plurality of second horizontal dowel bars and the corresponding first horizontal dowel bars by filling the first grout coupler with grouting material;

- each of the plurality of second grout couplers further includes a second groove disposed inside an inner cross-section area of the chimney section and coupled to a plurality of connecting bars disposed lengthwise along the inner cross-section area of the chimney section.

BRIEF DESCRIPTION OF DRAWINGS

[0010] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[0011] Figure 1 illustrates a front view of a precast foundation assembly for a transmission tower, in accordance with an example implementation of the present subject matter;

[0012] Figure 2A illustrates a top view of a bottom foundation section of the precast foundation assembly, in accordance with an example implementation of the present subject matter;

[0013] Figures 2B-2E illustrate a top view of a first bottom slab, a second bottom slab, a third bottom slab, and a fourth bottom slab, respectively, of the bottom foundation section of the precast foundation assembly, in accordance with an example implementation of the present subject matter;

[0014] Figure 3 illustrates a front view of the bottom foundation section of the precast foundation assembly, in accordance with an example implementation of the present subject matter;

[0015] Figure 4 illustrates another top view of the bottom foundation section of the precast foundation assembly with cover plate, in accordance with an example implementation of the present subject matter;

[0016] Figure 5A illustrates a top view of a top foundation section of the precast foundation assembly, in accordance with an implementation of the present subject matter;

[0017] Figure 5B-1 illustrates a front view of a second top slab of the top foundation section of the precast foundation assembly, in accordance with an implementation of the present subject matter;

[0018] Figure 5B-2 illustrates a front view of a first top slab of the top foundation section of the precast foundation assembly, in accordance with an implementation of the present subject matter;

[0019] Figure 5C illustrates a front view of the top foundation section placed atop the bottom foundation section, in accordance with an implementation of the present subject matter;

[0020] Figure 5D illustrates a front view of the top foundation section of the precast foundation assembly, in accordance with an implementation of the present subject matter; and

[0021] Figure 6 illustrates another front view of the precast foundation assembly for the transmission tower, in accordance with an example implementation of the present subject matter.

DETAILED DESCRIPTION

[0022] The present subject matter relates to a foundation of transmission towers.

[0023] The transmission towers are constructed over foundations that support upper tower structure and associated overhead transmission cables and thus play an important role in the safety and satisfactory performance of a power transmission infrastructure.

[0024] Usually, the foundations are cast-in-situ, that is, the foundations are constructed at a site where the transmission towers are to be built. However, the cast-in-situ approach to constructing the foundations requires careful supervision and quality control of materials used in the construction. Moreover, the cast-in-situ approach is very labor-intensive and may take a long time to complete. The cast-in-situ approach is also not preferred in cases where the construction may cause obstruction at the site or locations in proximity to the site.

[0025] A known alternative to the cast-in-situ approach to building the foundations involves use of precast foundations. The precast foundations are distinguished from cast-in-situ foundations in that the precast foundations are pre-engineered and manufactured in a controlled environment. The precast foundations are usually manufactured off-site in a manufacturing plant and then transported to the site where the transmission tower is to be built, where they are assembled to provide the foundation for the transmission tower.

[0026] In some cases, power transmission lines are routed through areas of poor ground conditions, often for reasons of amenity. This may result in the need for the use of special, generally larger, foundations. While small foundations can be precast in one piece, for large precast foundations, for example, where the weight of the foundation is more than 8 metric tons or the dimensions are more than 3m, the precast foundations are usually not preferred due to certain logistical constraints. For example, the site where the transmission tower is to be erected may be at a distance from the manufacturing plant of the precast foundations. In that case, the transportation of the large precast foundations may require large-size vehicles to transport the precast foundations to the site. Additionally, to load the precast foundations onto the vehicle, high-capacity cranes are required for lifting and placing the precast foundations on the vehicle. Once the vehicle delivers the precast foundations to the erection site, similar high-capacity cranes are required to dismount the precast foundations from the vehicle and place them at the erection site of the transmission tower.

[0027] Thus, the precast foundations which are heavy and large are oftentimes cumbersome to handle without damage. In many cases, the reduced costs of the precast foundations are compensated by the transportation cost that involves not only the cost of transportation vehicles but also several other necessary equipments, such as cranes, as explained above.

[0028] A modular precast foundation assembly for use in the construction of a transmission tower is described in the present subject matter. In an embodiment, the foundation assembly of the present subject matter overcomes the above-described problems associated with the conventional devices and techniques available for the construction of foundations for the transmission towers and more specifically for precast foundations.

[0029] In accordance with an embodiment of the present subject matter, a precast foundation assembly for a transmission tower includes a bottom foundation section that comprises a plurality of bottom slabs. In an example, each of the plurality of bottom slabs is an individual unit in itself and can be fixed and connected to adjoining bottom slabs forming a flat top surface. The plurality of bottom slabs is connected so that a square or rectangular structure of the bottom foundation section is formed. In an example, the top surface of each of the plurality of bottom slabs comprises a plurality of upwardly protruding secondary dowel bars.

[0030] The precast foundation assembly further comprises a top foundation section comprising top slabs. In an example, the top foundation section comprises one or more top slabs. In an alternate example embodiment, the top foundation section may even be absent from the

precast foundation assembly. Each of the one or more top slabs includes a plurality of secondary sleeves that is disposed on a bottom surface of the top slabs. Herein as well, each of the top slabs is an individual unit in itself and forms a square or rectangular structure when connected. The bottom foundation section assembled with the top foundation section forms a base of the precast foundation assembly onto which a chimney section of the precast foundation assembly is supported.

[0031] To assemble the bottom foundation section and the top foundation section together, the plurality of secondary dowel bars is configured to receive the respective secondary sleeves of the top slabs when the top foundation section is mounted on the bottom foundation section. In an example, grouted couplers may be used for assembling the bottom foundation section and the top foundation section together. Further, in an example, a top surface of one of the top slabs comprises a plurality of tertiary dowel bars. The chimney section that is to be disposed atop the top foundation section comprises a plurality of second grout couplers. Each of the second grout couplers includes first grooves that are flushed towards a bottom portion of the chimney section. Each of the first grooves is to receive a corresponding tertiary dowel bar when erecting the chimney section atop the top foundation section.

[0032] Thus, to complete the precast foundation assembly for the transmission tower, the first grooves receive a corresponding tertiary dowel bar to connect the chimney section on the base formed by the bottom foundation section that is assembled together with the top foundation section.

[0033] By splitting the precast foundation into multiple sections, such as the bottom foundation section, the top foundation section, and the chimney section, which can be assembled together to form a complete foundation at the transmission tower erection site, the weight or size of an individual precast section of the foundation can be reduced significantly. This reduces the number of arrangements that are needed to facilitate the transportation of large precast foundations as well as the lifting capacity needed on the site.

[0034] Therefore, dividing the precast foundations into multiple small sections eventually enables faster completion with respect to cast-in-situ. This solves the transportation and erection challenges of large precast foundations, thereby contributing to considerable savings in the overall cost of construction of the power transmission infrastructure. Further, robust interconnections between each of these multiple small sections ensure that the overall strength and reliability of the foundation assembly made by assembling the multiple sections of the precast foundation assembly is equivalent to that of a foundation constructed in-situ.

[0035] The above and other features, aspects, and advantages of the subject matter will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter along with examples described herein and should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and examples are intended to encompass equivalents thereof. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components.

[0036] Figure 1 illustrates a precast foundation assembly 100 to be used in the building of a transmission tower, in accordance with an implementation of the present subject matter.

[0037] Though the explanation of embodiment depicted in the Figures refers to a precast foundation assembly of a transmission tower for power transmission, the systems, methods, and apparatuses of the embodiments of the present invention may be used for all types of similar applications. For instance, the techniques relating to the construction and installation of the precast foundation assembly described herein may be applied to precast structures for use in roads and railways. It will be appreciated that the precast foundation assembly may be used for a variety of structures, such as fly-overs, foot-over bridges, transmission towers for telecommunication infrastructures, and so on.

[0038] The precast foundation assembly 100 for the transmission tower, as shown in Figure 1 , in an implementation of the present subject matter, is made by assembling together three separate sections, that is, a bottom foundation section 102, a top foundation section 104, and a chimney section 106, respectively. When assembled together, the bottom foundation section 102 lies underneath the top foundation section 104, and the top foundation section 104 lies underneath the chimney section 106, as shown in Figure 1 . A detailed description of the bottom foundation section 102, the top foundation section 104, and the chimney section 106, respectively, are provided in reference to Figure 2 onwards.

[0039] Dividing the precast foundation into the bottom foundation section 102, top foundation section 104, and the chimney section 106, as is done in the present subject matter, provides various specific advantages over the conventionally used single large precast foundation structures. For example, a single large precast foundation structure is normally heavy once produced and cured, and excessive impact during transportation may damage the structure. As a result, usually, extra care needs to be undertaken to ensure that the large precast foundation structure reaches the transmission tower building site safely. Further, as discussed above, owing to the large size and weight, transportation and logistics challenges are involved.

[0040] Thus, dividing the precast foundation assembly 100 into the bottom foundation section 102, top foundation section 104, and the chimney section 106, with each of these sections comprising further smaller parts, reduces the weight and size of individual precast foundation sections, thereby making it easier to transport these small sections of the precast foundation structures to the site. Also, pre-casting the foundation structure divided into multiple small sections facilitates a safer and more efficient offloading and setting process.

[0041] Figure 2A illustrates a top view of the bottom foundation section 102 of the precast foundation assembly 100, in accordance with an implementation of the present subject matter. Figures 2B-2E illustrate a top view of a plurality of bottom slabs 202, 204, 206, 208 of the bottom foundation section 102, in accordance with an example implementation of the present subject matter. Figure 3 illustrates a front view of the bottom foundation section 102 of the precast foundation assembly 100, in accordance with an example implementation of the present subject matter. Figure 4 illustrates another top view of the bottom foundation section 102 of the precast foundation assembly 100, in accordance with an example implementation of the present subject matter. Since Figures 2B-2E, 3, and 4 illustrate an arrangement relationship of the plurality of bottom slabs 202, 204, 206, 208 constituting the bottom foundation section 102, for the sake of ease of explanation, Figures 2A-2E, 3, and 4 are explained together.

[0042] The bottom foundation section 102 forms a wide base of the precast foundation assembly 100. The bottom foundation section 102 comprises the plurality of bottom slabs. In the example embodiment depicted in Figures, the bottom foundation portion 102 comprises four bottom slabs 202, 204, 206, 208. However, such a number of the bottom slabs is not a limitation, and it will be appreciated based on the forthcoming description that the bottom foundation portion 102 can comprise any number of bottom slabs. For example, the bottom foundation section 102 may constitute a single bottom slab, two bottom slabs, or more than four bottom slabs. In the present example, each of the plurality of bottom slabs 202, 204, 206, 208 is a separate precast concrete unit. The design and configuration, such as load bearing capacity, weight, and dimensions of the bottom slabs may be determined based on the end application for which the precast foundation assembly 100 is intended to be used.

[0043] In one example, each of the plurality of bottom slabs 202, 204, 206, 208 may have a length in a range of 1 meter - 9 meters and a width in a range of 1 meter - 4 meters.

[0044] In an example embodiment depicted in Figure 2B, a plurality of first primary dowel bars 210 protruding upwardly from a top surface of a first bottom slab 202, is disposed adjacently at regular intervals along a first and second consecutive edge 212, 214 of the first bottom slab 202.

[0045] Similarly, in an example embodiment depicted in Figure 2C, a plurality of second primary dowel bars 216 protruding upwardly from a top surface of a second bottom slab 204, is disposed adjacently at regular intervals along a first and second consecutive edge 218, 220 of the second bottom slab 204.

[0046] In an example embodiment depicted in Figure 2D, a plurality of first primary sleeves 222 is disposed adjacently at regular intervals along a first and second consecutive edges 224, 226 of a third bottom slab 206. Similarly, in an example embodiment depicted in Figure 2E, a plurality of second primary sleeves 228 is disposed adjacently at regular intervals along a first and second consecutive edges 230, 232 of a fourth bottom slab 208.

[0047] A first stage of forming the precast foundation assembly 100 for the transmission tower, in accordance with an example of the present subject matter, is forming the bottom foundation section 102. The bottom foundation section 102 contacts a ground surface on which the transmission tower is to be built and thus is the bottom-most element of the foundation.

[0048] To form the bottom foundation section 102, each of the plurality of bottom slabs 202, 204, 206, 208 is connected fixedly with its adjoining bottom slab forming a complete bottom foundation portion 102, as shown in Figure 2A.

[0049] For this purpose, firstly, the first bottom slab 202 and the second bottom slab 204 are placed on the ground surface keeping them diagonally opposite to each other, as shown in Figure 2A. Thereafter, the third bottom slab 206 is positioned on the ground surface with respect to the position of the first bottom slab 202 and the second bottom slab 204 in such a manner that each of the first primary sleeves 222 is received by the respective first primary dowel bars 210 disposed on the second edge 214 of the first bottom slab 202 and the second primary dowel bars 216 disposed on the first edge 218 of the second bottom slab 204.

[0050] Similarly, the third bottom slab 208 is positioned on the ground surface with respect to the position of the first bottom slab 202 and the second bottom slab 204 in such a manner that each of the second primary sleeves 228 is received by the respective first primary dowel bars 210 disposed on the first edge 212 of the first bottom slab 202 and second primary dowel bars 216 disposed on the second edge 220 of the second bottom slab 204.

[0051] Although in the present example, the positioning of the third bottom slab 206 on the ground surface has been described first, it may be understood that the plurality of bottom slabs 202, 204, 206, 208 may be placed in any order so long as each of a plurality of primary dowel bars 210, 216 is received by corresponding primary sleeves 222, 228. In an example, when connected together, each of the plurality of bottom slabs 202, 204, 206, 208 lies in a same horizontal plane, as shown in Figure 2A.

[0052] In another example, to form the bottom foundation section 102, each of the plurality of bottom slabs 202, 204, 206, 208 are joined only with adjacent bottom slabs and not with a diagonally opposite bottom slab, as shown in Figure 2A.

[0053] In an example embodiment, the first bottom slab 202 may have a first overlap extension 234 extending from a periphery of the first and second consecutive edge 212, 214 of the first bottom slab 202. Further, each of the plurality of first primary dowel bars 210 may be disposed in the first overlap extension 234 across the first and second consecutive edge 212, 214 of the first bottom slab 202. Similarly, the second bottom slab 204 may have a second overlap extension 236 extending from a periphery of

the first and second consecutive edge 218, 220 of the second bottom slab 204.

[0054] Further, each of the plurality of second primary dowel bars 216 may be disposed in the second overlap extension 236 across the first and second consecutive edge 218, 220 of the second bottom slab 204. Further, the third bottom slab 206 may have a first recess 238 formed across a periphery of the first and second consecutive edges 224, 226 of the third bottom slab 206. Similarly, the fourth bottom slab 208 may have a second recess 240 formed across a periphery of the first and second consecutive edges 230, 232 of the third bottom slab 206.

[0055] In an example, each of the first overlap extension 234 and the second overlap extension 236 may have a reduced thickness compared to the rest of the first bottom slab 202 and the second bottom slab 204, respectively. The reduced thickness is such that a combined thickness of the first overlap extension 234 and the second overlap extension 236 in an overlap region of the plurality of bottom slabs 202, 204, 206, 208 is substantially the same as the rest of the slab. Further, when joined together, the first overlap extension 234 and the second overlap extension 236 align with the corresponding first primary sleeves 222, and the second primary sleeves 228 on the adjacent slabs 206, 208, thereby accommodating the corresponding dowel bars 210, 216 within the sleeves 222, 228.

[0056] In an example, to ensure adjacent bottom slabs do not deflect away from one another under the influence of external forces when the plurality of bottom slabs 202, 204, 206, 208 are joined together to form the bottom foundation section 102, the first overlap extension 234 projects into the respective first recess 238 formed across the periphery of the second edge 226 of the third bottom slab 206 and the second recess 240 formed across the periphery of the first edge 230 of the fourth bottom slab 206. Similarly, the second overlap extension 236 projects into the respective first recess 238 formed across the periphery of the first edge 224 of the third bottom slab 206 and the second recess 240 formed across the periphery of the second edge 232 of the fourth bottom slab 206.

[0057] For example, in Figure 3, a front view of the first bottom slab 202 and the third fourth bottom slab 206 is shown. When joined to form the bottom foundation section 102, the first primary dowel bars 210 disposed in the first overlap extension 234 across the second edge 214 of the first bottom slab 202 projects into the first recess 238 formed across the periphery of the second edge 226 of the third bottom slab 206, as shown in Figure 3. In some implementations, the overlap extension and recess may have shapes corresponding with one another so that the overlap extension can engage the recess in a mating engagement.

[0058] As shown in Figure 4, in an example, once the plurality of bottom slabs 202, 204, 206, 208 are joined together, a cover plate 402 of a predefined thickness comprising a plurality of through holes 404 may be placed over the bottom foundation section 102. The cover plate 402 may be placed over the bottom foundation section 102 in such a manner that each of the plurality of through holes 404 of the cover plate 402 is received by the respective first primary dowel bars 210 and the second primary dowel bars 216. In an example, each of the plurality of first primary dowel bars 210 and second primary dowel bars 216 may have threaded ends for attaching a threaded fastener onto each end of the first primary dowel bars 210 and second primary dowel bars 216 after placing the cover plate 402, thereby securing the cover plate 402 and the first primary dowel bars 210 and the second primary dowel bars 216 together.

[0059] Once the plurality of bottom slabs 202, 204, 206, 208 are joined together and the cover plate 402 is put in place in an arrangement illustrated shown in Figure 4, an empty area on the top surface of the bottom foundation section 102 is grouted, using a grouting material, to ensure a reliable connection between the bottom slabs 202, 204, 206, 208.

[0060] In an example, once the plurality of bottom slabs 202, 204, 206, 208 are joined together and the cover plate 402 is put in place in an

arrangement illustrated in Figure 4, any empty area on a top surface of the bottom foundation section 102 may be grouted to ensure a reliable connection between the bottom slabs 202, 204, 206, 208. In another example, a baker rod (not illustrated) may be provided on outer edges of the bottom foundation section 102 that may act as a barricade to prevent seepage of grouting material during its application.

[0061] In an example implementation of the present subject matter, each of the plurality of bottom slabs 202, 204, 206, 208 may comprise a plurality of secondary dowel bars 242 protruding upwardly from the top surface of each of the plurality of bottom slabs 202, 204, 206, 208. In an example, each of the plurality of bottom slabs 202, 204, 206, 208 may be in a form of a rectangle or squared shape precast concrete slab.

[0062] Figure 5A illustrates a top view of the top foundation section 104 of the precast foundation assembly 100, in accordance with an implementation of the present subject matter. Figure 5B-1 illustrates a front view of a second top slab 504 of the top foundation section 104 of the precast foundation assembly 100, in accordance with an implementation of the present subject matter; Figure 5B-2 illustrates a front view of a first top slab 502 of the top foundation section 104 of the precast foundation assembly 100, in accordance with an implementation of the present subject matter;

[0063] Further, Figure 5C illustrates a front view of the top foundation section placed atop the bottom foundation section 102, in accordance with an implementation of the present subject matter. Figure 5D illustrates a front view of the top foundation section 104 of the precast foundation assembly 100, in accordance with an implementation of the present subject matter. For the sake of ease of explanation, Figures 5A-5D are explained together.

[0064] The top foundation portion 104 comprises one or more top slabs 502, 504 in an example. Although Figures 5B-1 and 5B-2 show the two top slabs 502, 504 as separate precast concrete units of the top foundation portion 104, in an alternative embodiment, the top foundation portion 104 may include a single slab. In an example, each of the top slabs 502, 504 may comprise a plurality of secondary sleeves 506. Although illustrated as through holes in Figure 5A, it may be understood that each of the plurality of secondary sleeves 506 may also include recesses disposed only on a bottom surface of the top slabs 502, 504. Each of the plurality of secondary sleeves 506 may include a coupling element (not illustrated) and may be configured to receive the respective secondary dowel bars 242 protruding upwardly from the top surface of each of the plurality of bottom slabs 202, 204, 206, 208. In an example, the coupling element, which is to receive the respective secondary dowel bars 242 available on the top surface of each of the plurality of bottom slabs 202, 204, 206, 208, may be disposed towards the bottom surface of the top slabs 502, 504 in the secondary sleeves 506 also provided on the bottom surface of the top slab 502, 504.

[0065] For example, as shown in Figure 5C, when the two top slabs 502, 504 are placed atop the plurality of bottom slabs 202, 204, 206, 208, the plurality of secondary dowel bars 242 protrudes into the coupling element, thereby forming a complete top foundation portion 104 as shown in Figure 5A. In an example, the coupling element may be a grout coupler, but not limited thereto. A detailed description of the grout coupler is provided in reference to Figure 5D and Figure 6.

[0066] In an example, as shown in Figures 5B-1 and 5B-2, a first top slab 502 includes a first projection 508 extending horizontally outward in relation to the body of the first top slab 502 and located on a first side 510 of the first top slab 502. Similarly, a second top slab 504 includes a second projection 512 extending horizontally outward in relation to the body of the second top slab 504 and located on a second side of the second top slab 504 positioned opposite to the first side 510 of the first top slab 502. In another example, the first projection 508 and the second projection 512 form a third recess 516, and a fourth recess 518 on a top surface of the first top slab 502 and the second top slab 504, respectively, as shown in Figures 5B-1 and 5B-2.

[0067] Further, in an example, the first top slab 502 may include a plurality of first horizontal dowel bars 520 protruding horizontally outward from both the first projection 508 and the third recess 516. Furthermore, in an example, the fourth recess 518 of the second top slab 504, may include a plurality of second horizontal dowel bars 524 each disposed to align with respective first horizontal dowel bars 520 protruding from the third recess 516, as shown in Figure 5D.

[0068] As shown in a projected illustration of the second top slab 504 in Figure 5A, for accommodating the first horizontal dowel bars 520 protruding horizontally outward from the first projection 508, the second top slab 504 may include a plurality of horizontal sleeves 522. Each of the plurality of horizontal sleeves 522 is open from top and adapted to receive a predefined number of the first horizontal dowel bars 520 disposed on the first projection 508.

[0069] For example, the first horizontal dowel bars 520 may be disposed on the first projection 508 alternately in a row and column pattern. Each row may comprise 9 first horizontal dowel bars 520, as shown in Figure 5A. Further, each column may comprise 3 first horizontal dowel bars 520, as shown in Figure 5D. When the first top slab 502 is placed atop the bottom foundation section 102 by aligning the first top slab 502 with respect to the position of the second top slab 504, each column comprising 3 first horizontal dowel bars 520 is received by the respective single horizontal sleeve 522.

[0070] In an example, as shown in Figure 5D, each of the plurality of second horizontal dowel bars 524 and the corresponding first horizontal dowel bars 520 may be reinforced using a first grout coupler 526 to maintain continuity between the bottom foundation section 102 and the top foundation section 104. The first grout coupler 526 may have a recess on both sides. Herein, a shape of the recess may correspond to a cross-section of each of the plurality of second horizontal dowel bars 524 and the first horizontal dowel bars 520 disposed in the third recess 516 the first top slab 502. Also, in a direction perpendicular to the recess, the first grout coupler 526 may include one or more access points 528.

[0071] In an example, once each of the plurality of second horizontal dowel bars 524 and the corresponding first horizontal dowel bars 520 is accommodated in the recess, the access points 528 may be filled with the grouting material to fill any void present inside the first grout coupler 526 after accommodating the second horizontal dowel bars 524 and the corresponding first horizontal dowel bar 520.

[0072] In some embodiments of the present invention, a Non-Shrink Grout M80 may be used as the grouting material. In some alternative embodiments of the present invention, a Non-Shrink Grout M60 may be used as the grouting material. Both the Non-Shrink Grout M80 and the Non-Shrink Grout M60 are known in the art and need not be described in detail, will be understood that the grouting material may also include other materials, and the present invention is not limited thereto.

[0073] In one example, the first grout coupler 526 may come threaded either with each of the plurality of second horizontal dowel bars 524 or the corresponding first horizontal dowel bars 520 of the precast top slabs 502, 504. In another example, the first grout coupler 526 may be joined either with each of the plurality of second horizontal dowel bars 524 or the corresponding first horizontal dowel bars 520 from both ends and then grouted using grouting material.

[0074] Once each of the one or more top slabs 502, 504 are placed atop the bottom foundation section 102 in a manner described above the first grout coupler 526 is grouted, the remaining gap between the first top slab section 502 and the second top slab section 504 may be filled by the grouting material to ensure a reliable connection.

[0075] Placing the top slabs 502, 504 atop the bottom foundation section 102 completes the formation of a base for the precast foundation assembly 100.

[0076] Although in the present example, the top foundation section 104 is shown to comprise two separate slabs, i.e., the first top slab 502 and the second top slab 504, it will be understood that in alternate embodiments of the present invention, any number of slabs may be employed in the top foundation section 104. For example, the top foundation section 104 may be composed of a single slab in cases where the weight of the top foundation section 104 is less than 8 metric tons. In another example, the top foundation section 104 may be composed of two or more two slabs, where the weight of the top foundation section 104 top is 13 metric tons or more.

[0077] In an example, a distance between two consecutive first primary dowel bars 210, second primary dowel bars 216, first horizontal dowel bars 520, second horizontal dowel bars 524, tertiary dowel bars 530, first primary sleeves 222, second primary sleeves 228, secondary sleeves 506, horizontal sleeves 522, and tertiary sleeves may lie in a range of 50 - 300 millimeters.

[0078] In an example, each of the primary, secondary, and tertiary dowel bars, may be manufactured from any material that is of sufficient strength for the purpose, such as, stainless steel. Alternatively, the primary, secondary, and tertiary dowel bars may be manufactured from other materials including, but not limited to bronze, titanium, fiberglass composite materials, and carbon steel. In another example, a number of the primary, secondary, and tertiary dowel bars and the corresponding sleeves may not be limited to the example embodiments given herein and may vary depending on the size of the precast foundation assembly 100.

[0079] Figure 6 illustrates another front view of the precast foundation assembly 100 for the transmission tower, in accordance with an example implementation of the present subject matter.

[0080] Once the formation of the base is complete, the chimney section 106 of the precast foundation assembly 100 may be erected atop the top foundation section 104 to complete the formation of the precast foundation assembly 100. For doing so, a plurality of tertiary dowel bars 530 may be disposed on a top surface of the first top slab section 502, as shown in Figure 5A. In an example embodiment not shown here, the chimney section 106 and the top foundation section 104 may be a single formation of the precast foundation assembly 100.

[0081] Although in the present example, the plurality of tertiary dowel bars 530 are shown to be disposed on the first top slab section 502, it will be understood that disposing the tertiary dowel bars 530 on the second top slab 504 or both is also possible.

[0082] For forming a connection with the plurality of tertiary dowel bars 530, the precast chimney section 106 may comprise a plurality of second grout couplers 602. The second grout coupler 602 may be similar to the first grout coupler 526. Each of the plurality of second grout couplers 602 may include a first groove 604 that may be flushed towards a bottom portion 606 of the chimney section 106. Each of the plurality of second grout couplers 602 may further include a second groove 608 that is disposed inside an inner cross-section area of the chimney section 106. The second groove 608 may be coupled to each of a plurality of bars 610 disposed lengthwise along the inner cross-section area of the chimney section 106, as shown in Figure 6. The second groove 608 may be coupled to one end of each of the plurality of bars 610, for example, by means of threading. In an example, the bars 610 may be a steel bar or other similar structure that may be reinforced inside the inner cross-section of the chimney section 106. Other end of each of the plurality of the bars 610, which is towards the bottom portion 606 of the chimney section 106, may be exposed to the tertiary dowel bar 530.

[0083] In an example, to erect the chimney section 106 atop the top foundation section 104, the first groove 604 of each of the plurality the second grout couplers 608 facing the top surface of the first top slab 502 may be aligned to receive the respective tertiary dowel bar 530.

[0084] Once each of the plurality of tertiary dowel bars 530 is received by the respective first groove 604 of each of the plurality of the second grout coupler 608, one or more access points (not illustrated) of the second grout coupler 608 may be filled with the grouting material to fill any void present inside the second grout coupler 608 after accommodating the tertiary dowel bars 530.

[0085] Although in the present example, as shown in Figure 6, the chimney section 106 is shown to be inclined, the scope of the present subject matter extends also to those embodiments where the chimney section 106 is not inclined.

[0086] Thus, a complete precast foundation assembly 100 is formed by connecting the chimney section 106 on the base formed by the bottom foundation section 102 and the top foundation section 104, respectively.

[0087] The methods and devices of the present subject matter offer techniques to split the precast foundation into multiple sections, such as the bottom foundation section, the top foundation section, and the chimney section, which are easy to assemble to form a complete precast foundation at the transmission tower erection site. By splitting the precast foundation into multiple sections, the weight or size of an individual precast section of the foundation may be reduced significantly, thereby making it possible to reduce the efforts needed to facilitate the transportation of large precast foundations as well as the lifting capacity for the same.

[0088] Although embodiments for methods and systems for the present subject matter have been described in a language specific to structural features and/or methods, it is to be understood that the present subject matter is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as exemplary embodiments of the present subject matter.

I/We Claim:

1. A precast foundation assembly (100) for a transmission tower, the precast foundation assembly (100) comprising:

a bottom foundation section (102) comprising a plurality of bottom slabs (202, 204,206, 208), each of the plurality of bottom slabs (202, 204) being connected to adjoining bottom slabs (206, 208) to form a flat top surface,

wherein the top surface formed by the plurality of bottom slabs (202, 204,206, 208) comprises a plurality of upwardly protruding secondary dowel bars (242);

a top foundation section (104) comprising one or more top slabs (502, 504), wherein each of the one or more top slabs (502, 504) comprises a plurality of secondary sleeves (506) disposed on a bottom surface of each of the one or more top slabs (502, 504),

wherein, to assemble the top foundation section (104) on the bottom foundation section (102), each of the plurality of secondary sleeves is to accommodate a corresponding secondary dowel bar (242),

wherein a top surface of one of the one or more top slabs (502, 504) comprises a plurality of tertiary dowel bars (530); and

a chimney section (106) to be disposed atop the top foundation section (104), the chimney section (106) comprising a plurality of second grout couplers (602) having first grooves (604) flushed towards bottom portion (606) of the chimney section (106), wherein each of the first grooves (604) is to receive a corresponding tertiary dowel bar (530) when erecting the chimney section (106) atop the top foundation section (104).

2. The precast foundation assembly (100) as claimed in claim 1 , wherein each of the plurality of bottom slabs (202, 204, 206, 208) is a separate precast concrete unit.

3. The precast foundation assembly (100) as claimed in claim 1 , wherein each of the plurality of bottom slabs (202, 204, 206, 208) have a length in a range of 1 - 9 meters and a width in a range of 1 - 4 meters.

4. The precast foundation assembly (100) as claimed in claim 1 , wherein a first bottom slab (202) and a second bottom slab (204) of the plurality of bottom slabs (202, 204, 206, 208) comprising first primary dowel bars (210) and second primary dowel bars (216), respectively, are located diagonally opposite to each other and a third bottom slab (206) and a fourth bottom slab (208) of the plurality of bottom slabs (202, 204, 206, 208) comprising first primary sleeves (222) and second primary sleeves (228), respectively, are located diagonally opposite to each other,

wherein the first primary dowel bars (210) and the second primary dowel bars (216) are disposed on two consecutive edges (212, 214, 218, 220) of the first bottom slab (202) and the second bottom slab (204), respectively, interfacing with edges (230, 226, 224, 232) of the third bottom slab (206) and fourth bottom slab (208), respectively, the first primary sleeves (222) and the second primary sleeves (228) being disposed on the edges (230, 226, 224, 232) of the third bottom slab (206) and fourth bottom slab (208) interfacing with the first bottom slab (202) and the second bottom slab (204),

wherein, to form a connection between each of the plurality of bottom slabs (202, 204, 206, 208) within the bottom foundation section (102), the first primary dowel bars (210) are inserted into the corresponding first primary sleeves (222), and the second primary dowel bars (216) are inserted into the corresponding second primary sleeves (228).

5. The precast foundation assembly (100) as claimed in claim 4, wherein the first primary dowel bars (210) are disposed within a first overlap extension (234) extending from a periphery of the first bottom slab (202) along a first and second consecutive edge (212, 214) of the first bottom slab (202), and the second primary dowel bars (216) are disposed within a second overlap extension (236) extending from a periphery of the second bottom slab (204) along a first and second consecutive edge (218, 220) of the second bottom slab (204),

wherein each of the first overlap extension (234) and the second overlap extension (236) has a reduced thickness compared to the rest of the first bottom slab (202) and the second bottom slab (204), respectively, the reduced thickness being such that a combined thickness of the first overlap extension (234) and the second overlap extension (236) in an overlap region of the plurality of bottom slabs (202, 204,206, 208) is substantially same as the rest of the slab, and when joined together, the first overlap extension (234) and the second overlap extension (236) align with the corresponding first primary sleeves (222), and the second primary sleeves (228) on the adjacent slabs (206, 208), to accommodate the dowel bars (210, 216) within the sleeves (222, 228).

6. The precast foundation assembly (100) as claimed in claim 5, wherein the third bottom slab (206) comprises a first recess (238) formed across a merging line of the first edge (224) and second edge ( 226) of the third bottom slab (206), and the fourth bottom slab (208) comprises a second recess (240) formed across a merging line of the first and second edge (230, 232) of the fourth bottom slab (206), wherein, when joining the plurality of bottom slabs (202, 204, 206, 208) to form the bottom foundation section (102), the first overlap extension (234) extends into the respective first recess (238), and the second overlap extension (236) extends into the respective second recess (240).

7. The precast foundation assembly (100) as claimed in claim 1 , further comprising a cover plate (402) of predefined thickness, the cover plate (402) being positioned over the top surface of the bottom foundation section (102) once the plurality of bottom slabs (202, 204, 206, 208) are joined together.

8. The precast foundation assembly (100) as claimed in claim 1 , wherein a first top slab (502) of the one or more top slabs (502, 504) includes a first projection (508) extending horizontally outward on one side and a second top slab (502) of the one or more top slabs (502, 504) includes a second projection (512) extending horizontally outward on a side opposite to the first projection (508), wherein the first projection (508) and the second projection (512) together form a third recess (516) and a fourth recess (518) on the top surface of the top two slabs (502, 504).

9. The precast foundation assembly (100) as claimed in claim 8, wherein the first projection (508) of the first top slab (502) includes a plurality of first horizontal dowel bars (520) protruding horizontally outward, and the fourth recess (518) of the second top slab (504) includes a plurality of second horizontal dowel bars (524) to align with the first horizontal dowel bars (520) of the first top slab (502).

10. The precast foundation assembly (100) as claimed in claim 8, wherein the first top slab (502) further includes a plurality of horizontal sleeves (522) open from the top, each adapted to receive a first horizontal dowel bar (520) disposed on the first projection (508).

1 1. The precast foundation assembly (100) as claimed in claim 1 , wherein the first top slab (502) and the second top slab (504) have an asymmetrical surface area, and the plurality of tertiary dowel bars (530) is disposed on the top slab (502) having a larger surface area.

12. The precast foundation assembly (100) as claimed in claim 9, wherein a first grout coupler (526) is used to reinforce each of the plurality of second horizontal dowel bars (524) and the corresponding first horizontal dowel bars (520) by filling the first grout coupler (526) with grouting material.

13. The precast foundation assembly (100) as claimed in claim 1 , wherein each of the plurality of second grout couplers (602) further includes a second groove (608) disposed inside an inner cross-section area of the chimney section (106) and coupled to a plurality of connecting bars (610) disposed lengthwise along the inner cross-section area of the chimney section (106).