Prefabricated box type transformer box foundation and construction method

Abstract

The application discloses a prefabricated box-shaped box transformer foundation and a construction method, and relates to the technical field of box transformer foundations. The foundation comprises a bottom plate and a plurality of vertically arranged side walls, and the bottom plate and the side walls jointly enclose an installation area with an open top, a manhole area and an oil pool area. A box transformer connecting embedded part is arranged on the upper end of the side wall corresponding to the installation area, a ventilation opening is arranged on the side wall, a ladder embedded bolt is arranged on the inner wall of the side wall corresponding to the manhole area, a prefabricated water collecting pit is assembled on the bottom plate, and an oil discharge opening is arranged on the side wall corresponding to the oil pool area. The bottom plate, the side walls and the water collecting pit are all reinforced concrete prefabricated structures. The side walls are divided into a lower foundation integrally formed with the bottom plate and an upper foundation abutted and spliced. Mechanical abutting structures, flat steel reinforcements and multiple waterproof structures are arranged at the joints. The application adopts a construction mode of factory prefabrication and on-site assembly, and can solve the problems of difficulty in guaranteeing the construction strength, complicated procedures and high cost in the winter construction in severe cold areas.

Description

Technical Field

[0001] This invention relates to the field of prefabricated box-type substation foundation technology, specifically to a prefabricated box-type substation foundation and its construction method. Background Technology

[0002] With the rapid development of the new energy industry, the construction scale of wind power and photovoltaic projects continues to expand. These projects have stringent requirements for grid connection and commissioning time, and meeting the construction schedule and grid connection requirements have become the core management objectives of project construction. In cold regions, the harsh winter climate, with nighttime temperatures often dropping below 0°C and extreme low temperatures reaching -40°C, brings many difficult technical challenges to the construction of transformer substation foundations.

[0003] Currently, in frigid regions, the foundations of transformer substations are mostly constructed using cast-in-place concrete. However, this method has significant drawbacks during winter construction. On the one hand, the low temperature environment severely affects the setting and hardening process of concrete, resulting in slow strength development and failure to meet design requirements. This significantly reduces the load-bearing capacity and durability of the foundation structure, making it difficult to meet the long-term stable operation requirements of the transformer substation equipment. On the other hand, to ensure the smooth construction of cast-in-place concrete in winter, a series of winter construction measures are required, such as erecting heated sheds, heating sand and gravel, steam curing, and insulation covering. These measures are not only cumbersome but also significantly increase construction costs, pushing up the overall project cost. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a prefabricated box-type transformer foundation and its construction method. This method adopts a construction mode of factory prefabrication and on-site assembly, which can solve the problems of difficulty in ensuring the strength of cast-in-place construction in cold regions during winter, complicated procedures, and high costs.

[0005] To address the aforementioned technical problems, this invention provides a prefabricated box-type transformer foundation, comprising a base plate and multiple vertically arranged side walls. The base plate and the side walls enclose an installation area with a top opening, a manhole area, and an oil sump area. Multiple embedded parts are provided on the upper surface of the side wall corresponding to the installation area, for welding to the transformer. Ventilation openings are provided on the side walls of the side walls corresponding to the installation area, and ventilation windows are installed at these openings. Multiple embedded nuts are provided on the inner wall of the side wall corresponding to the manhole area, for installing ladders. Through holes are provided on the base plate, and a water collection pit is provided within these through holes, with the water collection pit sealingly fitted to the hole wall. An oil drain outlet is provided on the side wall of one of the side walls corresponding to the oil sump area. The bottom plate and the bottom of the side wall are integrally formed and connected, and two adjacent side walls at the same horizontal level are integrally formed and connected. The bottom plate, side walls and sump pit are all precast reinforced concrete structures.

[0006] In some embodiments, the sidewalls are provided in two layers along the height direction. The multiple sidewalls include multiple lower sidewalls at the same horizontal height and multiple upper sidewalls at the same horizontal height. The upper sidewalls are located directly above the lower sidewalls. The multiple lower sidewalls enclose to form a lower foundation and the multiple upper sidewalls enclose to form an upper foundation. The upper surfaces of both the lower foundation and the upper foundation are pre-embedded with hoisting nails.

[0007] In some embodiments, a first interlocking portion is provided on the upper end face of the lower foundation, and a second interlocking portion is provided on the lower end face of the upper foundation. The first interlocking portion and the second interlocking portion interlock with each other and are fixedly connected by cast-in-place cement mortar.

[0008] In some embodiments, the first engagement portion is a groove formed on the upper end face of the lower foundation, and the second engagement portion is a protrusion integrally fixed to the lower end face of the upper foundation, wherein the protrusion is arranged corresponding to the groove.

[0009] In some embodiments, flat steel is provided at the joint between the lower foundation and the upper foundation, and the flat steel is fixedly connected to the lower foundation and the upper foundation respectively.

[0010] In some embodiments, the top surface of the sump is lower than the top surface of the base plate, a waterproof sealant is provided between the sump and the wall of the through hole, a waterproof membrane is laid at the location where the through hole is opened on the base plate, the waterproof membrane is laid from the outer edge of the through hole to the inner wall of the sump, and a water grate is provided on the top of the sump.

[0011] In some embodiments, a rubber pad is provided between the top of the grate and the sump.

[0012] In some embodiments, a plurality of frame beams are provided on the top of the installation area, and the plurality of frame beams are arranged along the length direction of the installation area.

[0013] In some embodiments, the oil tank area and the lower manhole area are located on one side of the installation area, and a maintenance platform is provided on the top of the other side of the installation area.

[0014] In some embodiments, cable holes are provided on the lower side wall.

[0015] On the other hand, the present invention provides a construction method for the precast box-type transformer foundation, comprising: Excavate the foundation pit to the bearing layer of the foundation according to the design requirements. After the foundation is leveled, compacted and accepted, pour the concrete cushion layer and cure it to the design strength. The prefabricated base slab and the integrated sub-foundation components are hoisted to the designated position on the sub-base and aligned in place. Assemble the prefabricated sump into the through hole of the base plate, fill the gap between the sump and the through hole wall with waterproof sealant, lay waterproof membrane to cover the joint and surrounding area, and install a water grate on the top of the sump. Cement mortar is poured into the first interlocking part on the upper end face of the lower foundation. The prefabricated upper foundation is then hoisted and aligned so that the second interlocking part on the lower end face of the upper foundation interlocks with the first interlocking part. After the cement mortar has hardened, the joint is waterproofed and the lower foundation and upper foundation are fixed together with flat steel. Install maintenance platforms and ventilation windows at the corresponding locations on the side walls, and complete the corresponding treatment of cable holes and oil drains; Plain concrete was poured onto the bottom slab of the oil pool area and cured to form an oil collection pit, thus completing the construction of the entire precast box-type transformer foundation.

[0016] The beneficial effects of this invention are as follows: 1. All core components of this invention, including the base plate, side walls, and sump pit, are precast reinforced concrete structures. They can be precast and cured in a standardized factory, and the strength, durability, and forming quality of the components are not affected by the low-temperature environment on site. On-site, only assembly processes such as hoisting and positioning, interlocking and connecting, and sealing of joints need to be completed. There is no need for cumbersome winter construction measures such as setting up heated sheds, heating sand and gravel, and steam curing. This fundamentally avoids the defects of slow strength growth and substandard performance of cast-in-place concrete in low-temperature environments, while significantly reducing winter construction costs. It can fully meet the core construction needs of wind power and photovoltaic projects to meet the time requirements and ensure grid connection.

[0017] 2. The present invention adopts a layered design with the lower foundation and base slab prefabricated as a whole, and the upper foundation prefabricated independently. The size and weight of individual components are suitable for conventional hoisting and road transportation conditions, solving the problems of excessive volume and difficult transportation of integral prefabricated components. The upper and lower foundations are mechanically interlocked through grooves and tenons, and with the joints filled with cast-in-place mortar and reinforced by external flat steel bridging, precise alignment during hoisting is achieved, and the shear resistance and horizontal displacement resistance of the joints are significantly improved, ensuring the overall rigidity and load-bearing capacity of the foundation and meeting the load requirements of the long-term operation of the prefabricated substation equipment.

[0018] 3. This invention can simultaneously integrate the three functional areas of installation area, manhole area and oil tank area during the prefabrication stage, and accurately pre-reserve all holes and embedded parts such as embedded parts, ventilation openings, cable holes, oil drains, and ladder embedded nuts in one go. There is no need for secondary drilling and rebar installation on site. This not only avoids the damage to the structural integrity and waterproof performance caused by on-site drilling, but also greatly improves assembly efficiency and installation accuracy, and achieves a high degree of integration of the functions of the transformer substation foundation.

[0019] 4. This invention addresses leakage risk points such as the joints of the sump pit, the joints between the upper and lower foundations, by setting up waterproof barriers to effectively prevent groundwater from seeping into the foundation, thereby improving the durability and operational safety of the foundation in a humid underground environment. Attached Figure Description

[0020] Figure 1 This is a perspective view of the prefabricated box-shaped transformer foundation of the present invention; Figure 2 This is a top view of the upper layer of the present invention; Figure 3 This is a top view of the base plate and lower foundation of the present invention; Figure 4 This is a cross-sectional view of the base plate and the lower foundation of the present invention; Figure 5 This is a diagram showing the layout of the waterproofing measures between the water collection pit and the base plate in this invention. Figure 6 This is a schematic diagram of the interlocking structure between the lower and upper foundations of the present invention.

[0021] Attached reference numerals: Base plate 1; Plain concrete 101; Lower foundation 2; Upper foundation 3; Sump 4; Waterproof sealant 41; Rubber pad 42; Waterproof membrane 43; Water grate 44; Flat steel 5; Lifting nail 6; Embedded nut 7; Embedded part 8; Oil drain 9; Frame beam 10; Louver 11; Maintenance platform 12; Oil tank area 13; Oil sump 14; Installation area 15; Steel grating 16; Groove 171; Tenon 172; Drainage hole 18; Cable hole 19; Manhole area 20. Detailed Implementation

[0022] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] like Figure 1 As shown, this invention discloses a prefabricated box-type transformer foundation, which is an overall prefabricated reinforced concrete assembly structure, including a horizontally arranged base plate 1 and multiple vertically arranged side walls. The base plate 1 and all the side walls together enclose three independent functional areas with a top opening, namely, an installation area 15 for supporting the main equipment of the box-type transformer, a manhole area 20 for maintenance personnel to enter and exit the foundation, and an oil sump area 13 for collecting and temporarily storing transformer leaked oil. Figure 2 As shown.

[0024] To accommodate road transport and on-site hoisting operations, the side walls are constructed in two layers: multiple lower side walls at the same horizontal level and multiple upper side walls at the same horizontal level. The upper side walls are located directly above the lower side walls. The multiple lower side walls enclose the lower foundation 2, and the multiple upper side walls enclose the upper foundation 3. Hoisting spikes 6 are pre-embedded on the upper surfaces of both the lower foundation 2 and the upper foundation 3. These hoisting spikes 6 are used for quick connection of rigging during crane hoisting, improving the convenience and safety of on-site hoisting operations. All lower side walls and the base plate 1 are integrally cast, and all upper side walls are integrally cast.

[0025] The lower foundation 2 and the upper foundation 3 adopt an interlocking splicing connection structure: the upper end face of the lower foundation 2 is provided with a first interlocking part, and the lower end face of the upper foundation 3 is provided with a second interlocking part. The first interlocking part and the second interlocking part interlock with each other and are fixedly connected by cast-in-place cement mortar.

[0026] like Figure 6 As shown, the first engagement part is a groove 171 continuously opened along the upper end face of the lower foundation 2, and the second engagement part is a tenon 172 (i.e. a protrusion) continuously provided along the lower end face of the upper foundation 3. The planar position and cross-sectional dimensions of the tenon 172 and the groove 171 correspond one-to-one. During assembly, the tenon 172 is embedded in the groove 171 to form a horizontal mechanical limit, which can effectively resist horizontal shear force and lateral displacement.

[0027] Meanwhile, flat steel 5 is provided on the outside of the joint between the lower foundation 2 and the upper foundation 3. The flat steel 5 spans the upper and lower sides of the joint and is fixedly connected to the pre-embedded nuts on the side walls of the lower foundation 2 and the upper foundation 3 by fastening bolts, which further strengthens the connection strength between the upper foundation and the lower foundation and improves the deformation resistance and integrity of the overall structure.

[0028] like Figure 2 As shown, multiple embedded parts 8 are pre-embedded on the upper surface of the side wall corresponding to installation area 15. The embedded parts 8 adopt the structure of embedded steel plate and anchor bar, and their upper surface is flush with the top surface of the side wall. They are used for subsequent welding and fixing to the base of the box-type substation to achieve a rigid and reliable connection between the box-type substation and the foundation. The side wall corresponding to installation area 15 has a through-hole ventilation opening. Louvers 11 are fixedly installed at the ventilation opening as ventilation windows to ensure air circulation inside the foundation, avoid heat and moisture accumulation at the bottom of the box-type substation, and ensure a stable operating environment for the equipment.

[0029] Multiple pre-embedded nuts 7 are pre-embedded on the inner wall of the side wall corresponding to the manhole area 20. The multiple pre-embedded nuts 7 are arranged at equal intervals in the vertical direction for the detachable installation of the maintenance ladder, so that maintenance personnel can enter the foundation through the manhole to carry out maintenance work.

[0030] like Figure 3As shown, a through hole is provided on the base plate 1 corresponding to the water collection position, and a prefabricated water collection pit 4 is installed in the through hole. Figure 5 As shown, the sump 4 is a precast reinforced concrete trough-shaped component with an open top, and its outer wall is sealed to the wall of the through hole. After the sump 4 is assembled, its top surface elevation is lower than that of the bottom plate 1, forming a recessed water collection space. Waterproof sealant 41 is filled between the outer wall of the sump 4 and the wall of the through hole in the bottom plate 1 to compact and seal the joint gap; waterproof membrane 43 is laid at the location of the through hole in the bottom plate 1, extending from the outer edge of the through hole to the upper part of the inner wall of the sump 4, forming a continuous and uninterrupted waterproof covering layer to block the path of groundwater seepage along the joint. A grate 44 is installed at the top opening of the sump 4 to intercept debris and prevent it from falling into and clogging the sump; a rubber pad 42 is placed between the grate 44 and the top surface of the sump 4. In addition, a drainage hole 18 is provided on the lower part of the side wall of the sump 4. The drainage hole 18 is connected to the outside of the foundation through a pipe, so that the water accumulated in the sump can be discharged outside the foundation.

[0031] like Figure 2 As shown, an oil drain port 9 is provided on one of the side walls of the oil tank area 13. The oil drain port 9 connects the interior of the oil tank area with the exterior of the foundation and is used to drain the transformer oil accumulated in the oil tank; as shown Figure 4 As shown, plain concrete 101 is poured on the bottom plate 1 of the oil pool area 13 to form an inwardly recessed oil collection pit 14, which is used to collect transformer oil leaking from the equipment for centralized treatment.

[0032] like Figure 1 , 2 As shown, multiple frame beams 10 are provided on the top of the installation area 15. The multiple frame beams 10 are evenly spaced along the length of the installation area 15. The two ends of the frame beams 10 are integrally prefabricated or pre-embedded to the top of the corresponding side wall to enhance the structural strength of the top of the installation area and distribute the load of the transformer substation equipment.

[0033] Oil tank area 13 and manhole area 20 are arranged side by side on one side of installation area 15. A maintenance platform 12 is installed on the top of the other side of installation area 15. Maintenance platform 12 is a steel structure, including supporting steel beams and steel grating 16. The supporting steel beams are welded and fixed to embedded parts in the side wall, and the steel grating 16 is laid on top of the steel beams, providing a safe maintenance operating space for maintenance personnel. Cable holes 19 are also provided on the lower side wall of the lower foundation 2 for running power cables, enabling cable access for the transformer substation equipment.

[0034] This invention also discloses a construction method for the aforementioned precast box-type transformer foundation, specifically including the following steps: S1. Excavate the foundation pit according to the design drawings until the foundation bearing layer required by the design is reached. After the bottom of the foundation pit is leveled, compacted and inspected and approved, pour plain concrete cushion layer. After the cushion layer concrete reaches the design strength, a flat working reference surface is formed, which provides the foundation conditions for the subsequent hoisting of precast components.

[0035] S2. Using a crane in conjunction with the lifting nails 6 on the top of the lower foundation 2, the prefabricated base plate 1 and the integrated component of the lower foundation 2 are smoothly lifted to the designed position in the foundation pit, and the plane coordinates and top elevation are calibrated to ensure accurate positioning of the component.

[0036] S3. Hoist the prefabricated sump pit 4 into the installation through hole of the base plate 1. After adjusting the position and elevation, fill the annular gap between the outer wall of the sump pit 4 and the wall of the through hole with waterproof sealant 41 and compact it to seal. Then, lay the waterproof membrane 43 at the through hole position of the base plate, so that the waterproof membrane 43 extends from the outer edge of the through hole to the upper part of the inner wall of the sump pit 4 to form a complete waterproof surface. After that, lay the rubber pad 42 on the top surface of the sump pit 4. Finally, cover the top opening of the sump pit 4 with the water grate 44 to complete the assembly and waterproofing of the sump pit.

[0037] S4. First, pour cement mortar into the groove 171 at the top of the lower foundation 2. Then, use a crane with the lifting nails 6 at the top of the upper foundation 3 to lift the upper foundation 3 directly above the lower foundation 2, so that the tenon 172 at the bottom of the upper foundation 3 is accurately embedded into the groove 171. Fill the interlocking gap with cement mortar to eliminate the local suspension problem caused by component processing deviation. After the cement mortar has solidified and hardened, the interlocking and fixing of the upper and lower foundations is achieved.

[0038] Waterproof membrane is laid inside the joint between the upper and lower foundations to ensure proper waterproofing. Meanwhile, flat steel 5 is installed on the outside of the joint and fixed to the side walls of the lower foundation 2 and the upper foundation 3 with fastening bolts to enhance the overall connection rigidity of the foundation.

[0039] S5. Weld supporting steel beams onto the embedded parts of the side wall corresponding to the upper foundation 3. The steel beams are arranged perpendicular to the side wall. After connecting the steel beams into an integral steel frame, lay steel grating 16 on the top surface of the steel frame to complete the construction of the maintenance platform 12. Steel grating can be laid in the same way in the oil tank area 13. At the same time, complete the installation of louvers 11, sealing pretreatment of cable holes 19 and other supporting operations.

[0040] S6. Pour plain concrete 101 on the base plate 1 of the oil pool area 13. After curing, an oil collection pit 14 is formed, thus completing all construction procedures of the entire precast box-type transformer foundation.

[0041] The subsequent prefabricated substation can be directly hoisted into place, and the base of the prefabricated substation can be fixedly connected to the pre-embedded parts 8 on the top of the upper foundation 3 by welding, thus completing the installation of the prefabricated substation equipment.

[0042] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A prefabricated box-type transformer foundation, characterized in that, The system includes a base plate (1) and multiple vertically arranged side walls. The base plate (1) and multiple side walls enclose an installation area (15) with a top opening, a lower manhole area (20), and an oil tank area (13). Multiple embedded parts (8) are provided on the upper surface of the side wall corresponding to the installation area (15). The embedded parts (8) are used for welding with the transformer. Ventilation openings are opened on the side walls of the side walls corresponding to the installation area (15). Ventilation windows are installed at the ventilation openings. Multiple embedded nuts (7) are provided on the inner wall of the side wall corresponding to the lower manhole area (20). The embedded nuts (7) are used for installing ladders. Through holes are opened on the base plate (1). A water collection pit (4) is provided in the through holes. The water collection pit (4) is sealed to the hole wall of the through holes. An oil drain port (9) is opened on the side wall of one of the side walls corresponding to the oil tank area (13). The bottom plate (1) is integrally formed and connected to the bottom of the side wall, and two adjacent side walls at the same horizontal level are integrally formed and connected. The bottom plate (1), side wall, and sump (4) are all precast reinforced concrete structures.

2. The prefabricated box-type transformer foundation according to claim 1, characterized in that, The sidewalls are arranged in two layers along the height direction. The multiple sidewalls include multiple lower sidewalls at the same horizontal height and multiple upper sidewalls at the same horizontal height. The upper sidewalls are located directly above the lower sidewalls. The multiple lower sidewalls enclose to form a lower foundation (2), and the multiple upper sidewalls enclose to form an upper foundation (3). The upper surfaces of the lower foundation (2) and the upper foundation (3) are pre-embedded with hoisting nails (6).

3. The prefabricated box-type transformer foundation according to claim 2, characterized in that, The upper end face of the lower foundation (2) is provided with a first interlocking part, and the lower end face of the upper foundation (3) is provided with a second interlocking part. The first interlocking part and the second interlocking part interlock with each other and are fixedly connected by cast-in-place cement mortar.

4. A prefabricated box-type transformer foundation according to claim 3, characterized in that, The first engagement part is a groove (171) formed on the upper end face of the lower base (2), and the second engagement part is a protrusion integrally fixed on the lower end face of the upper base (3). The protrusion is arranged corresponding to the groove (171).

5. A prefabricated box-type transformer foundation according to claim 3, characterized in that, Flat steel (5) is provided at the joint between the lower foundation (2) and the upper foundation (3), and the flat steel (5) is fixedly connected to the lower foundation (2) and the upper foundation (3) respectively.

6. A prefabricated box-type transformer foundation according to any one of claims 1 to 5, characterized in that, The top surface of the water collection pit (4) is lower than the top surface of the bottom plate (1). Waterproof sealant (41) is provided between the water collection pit (4) and the wall of the through hole. Waterproof membrane (43) is laid at the location where the through hole is opened on the bottom plate (1). The waterproof membrane (43) is laid from the outer edge of the through hole to the inner wall of the water collection pit (4). A water grate (44) is provided on the top of the water collection pit (4).

7. A prefabricated box-type transformer foundation according to claim 6, characterized in that, A rubber pad (42) is provided between the top of the water grate (44) and the water collection pit (4).

8. A prefabricated box-type transformer foundation according to any one of claims 1 to 5, characterized in that, Multiple frame beams (10) are provided on the top of the installation area (15), and the multiple frame beams (10) are arranged along the length direction of the installation area (15).

9. A prefabricated box-type transformer foundation according to any one of claims 1 to 5, characterized in that, The oil tank area (13) and the lower manhole area (20) are located on one side of the installation area (15), and an inspection platform (12) is provided on the top of the other side of the installation area (15).

10. A construction method for a prefabricated box-type transformer foundation as described in any one of claims 1 to 9, characterized in that, include: Excavate the foundation pit to the bearing layer of the foundation according to the design requirements. After the foundation is leveled, compacted and accepted, pour the concrete cushion layer and cure it to the design strength. The prefabricated base plate (1) and the lower foundation (2) are hoisted together to the designated position of the cushion layer and aligned in place. The prefabricated water collection pit (4) is assembled into the through hole of the base plate (1), and the gap between the water collection pit (4) and the through hole wall is sealed by filling with waterproof sealant (41). Waterproof membrane (43) is laid to cover the joint and surrounding area, and a water grate (44) is installed on the top of the water collection pit (4). Cement mortar is poured into the first interlocking part on the upper end face of the lower foundation (2), and the prefabricated upper foundation (3) is hoisted and aligned so that the second interlocking part on the lower end face of the upper foundation (3) and the first interlocking part are interlocked. After the cement mortar has solidified and hardened, the joint is waterproofed and the lower foundation (2) and the upper foundation (3) are fixed by cross-connection with flat steel (5). Install the maintenance platform (12) and ventilation window at the corresponding position on the side wall, and complete the matching treatment of cable hole (19) and oil drain (9); Plain concrete (101) is poured on the base plate (1) of the oil pool area (13) and cured to form an oil collection pit (14), thus completing the construction of the entire precast box-type transformer foundation.

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