A transformer foundation with high seismic strength and restorable caisson structure

Abstract

The present invention relates to the field of transformer earthquake resistance technology, and specifically to a transformer foundation with a caisson structure that is highly earthquake-resistant and has recoverable strength. The bottom of the transformer oil tank is set on the ground, and the caissons are symmetrically distributed on both sides or around the bottom of the transformer oil tank. The bottom of the transformer oil tank bottom is overlapped on the caisson, and each caisson is fixed to the transformer oil tank bottom at the overlap by fixing the transformer bolts. The anchor bolts located underground pass through the bottom of the caisson and are welded to the caisson; the limit device is set under the ground around the bottom of the transformer oil tank, and a limit fixing plate is set on the top of each limit device, and the limit fixing plate is close to the four sides of the bottom of the transformer oil tank. The present invention ensures that the transformer can still operate stably for a long time in a high-intensity earthquake environment with frequent earthquakes, avoids the problem of weakened earthquake resistance due to damage to the transformer fixings after an earthquake, and realizes the recoverability of earthquake resistance.

Description

Technical Field

[0001] The invention relates to the technical field of transformer earthquake resistance, in particular to a transformer foundation with a caisson structure having high earthquake resistance and recoverable strength. Background Art

[0002] Transformers are one of the most important equipment in power systems and are widely used in various regions around the world. For power equipment installed in earthquake-prone areas with magnitudes 9 to 10, sudden earthquakes can cause catastrophic damage to them, and the cost of repairing them after damage is inestimable.

[0003] At present, in the domestic power system equipment, the transformer foundation generally adopts the structure of welding the transformer box bottom and the foundation or pouring anchor bolts into concrete. The anchor bolts embedded in the concrete base are directly installed on the bottom of the transformer box to fix the transformer. This structure can limit the displacement and vibration amplitude of the transformer to a certain extent, but for transformers installed in earthquake-prone areas, the foundation cannot be restored after being damaged by multiple earthquakes. For example, Chile has an average of more than 1,800 earthquakes per year, and Japan has an average of more than 1,000 earthquakes per year. In the harsh environment brought by sudden earthquakes in these areas, the anchor bolts will be affected by radial and shear forces at a high frequency, reducing their fatigue life and causing them to be damaged. The anchor bolts installed at the bottom of the transformer oil tank are poured in concrete, and cannot be replaced after damage, resulting in them only being able to withstand the earthquake intensity for a short time. However, the life of the transformer is 30 years, and the bearing capacity of the transformer foundation of this similar structure cannot meet the service life of the transformer.

[0004] Another traditional transformer vibration reduction method is to install a vibration reduction device at the bottom of the transformer, but this structure is usually complicated, cumbersome to manufacture, and has a high cost.

[0005] China Invention Patent Publication No. CN104376972A proposes a 500kV transformer seismic isolation structure and installation method, which achieves seismic resistance by adding isolators to the foundation. The structure is complex and the cost is high. China Invention Patent Publication No. CN112281904A proposes a transformer seismic universal foundation structure and method, which effectively reduces the impact vibration of the transformer during an earthquake through the cooperation of components such as marbles and springs. This invention only alleviates the impact vibration caused by an earthquake to a certain extent. At present, there has been no report on the transformer foundation using a caisson structure with high seismic resistance and recoverable strength. Summary of the invention

[0006] In view of the problems in the prior art that the transformer shock-absorbing device is costly and the anchor bolts in the foundation cannot be replaced after being damaged, the purpose of the present invention is to provide a transformer foundation with a caisson structure that is highly seismic-resistant and has recoverable strength. This foundation can withstand earthquakes of magnitude 9 to 10. By adopting a special caisson structure, the fasteners that fix the transformer can be replaced regularly, and the force is transmitted to the base through the caisson embedded in the concrete to ensure the seismic resistance of the transformer for long-term operation.

[0007] The technical solution of the present invention is:

[0008] A transformer foundation with a high seismic strength and restorable caisson structure, the transformer foundation comprises: a transformer oil tank bottom, a limit device, a caisson, anchor bolts, and transformer fixing bolts, and the specific structure is as follows:

[0009] The bottom of the transformer oil tank is set on the ground, and the caissons are symmetrically distributed on both sides or around the bottom of the transformer oil tank. The bottom of the transformer oil tank is overlapped on the caisson, and each caisson is fixed to the overlap of the transformer oil tank bottom by fixing the transformer bolts. The anchor bolts located underground pass through the bottom of the caisson and are welded to the caisson; the limit device is set under the ground around the bottom of the transformer oil tank, and a limit fixing plate is set on the top of each limit device, and the limit fixing plate is close to the four sides of the bottom of the transformer oil tank.

[0010] The transformer foundation of the caisson structure with high seismic strength and recoverable structure is characterized in that the caisson cover plate covers the upper opening of the caisson, and concrete is poured around the limit device, caisson and anchor bolts below the ground to form the transformer foundation.

[0011] The transformer foundation of the high seismic strength restorable caisson structure is configured such that after concrete is poured, the transformer oil tank is installed on the bottom of the transformer oil tank, and a limiting fixing plate is welded on the limiting device to limit the displacement of the transformer oil tank and the bottom of the transformer oil tank.

[0012] The transformer foundation of the high seismic strength restorable caisson structure, the caisson consists of a box upper cover plate, a box inner fixed plate, an upper rib plate, a box body, and a lower rib plate. The box upper cover plate is horizontally welded on one side of the box top opening, and there are one or more box upper covers. The box inner fixed plates corresponding to the box upper cover plate are horizontally welded on the middle inner wall of the box body. A "U-shaped groove" is formed between the corresponding box upper cover plate, the box inner fixed plate and the middle inner wall of the box body. The edges between the box upper cover plate and the box inner fixed plate are welded by a vertical upper rib plate, and the box inner fixed plate and the box inner bottom are welded by a vertical lower rib plate. The transformer fixing bolts are penetrated through the corresponding box upper cover plate, the box inner fixed plate and the transformer oil tank bottom overlapped on the caisson, so that the caisson is connected and fixed to the transformer oil tank bottom.

[0013] The transformer foundation of the caisson structure with high seismic strength and recoverability has a space on the other side of the top opening of the box body for fixing the installation of transformer bolts.

[0014] The transformer foundation of the high seismic strength restorable caisson structure is that the bottom of the transformer oil tank is a rectangular steel plate with connecting blocks symmetrically arranged on both sides or all around, the connecting blocks correspond to the caisson one by one, the bottom of the transformer oil tank is overlapped on the upper cover plate of the caisson through the connecting blocks, the connecting blocks are provided with oblong mounting holes for the bolts for fixing the transformer to pass through, and the bottom reinforcement irons are arranged on the two edges and the middle of the upper surface of the connecting blocks.

[0015] The transformer foundation of the high seismic strength restorable caisson structure, the bottom reinforcement iron of the box is respectively located between and on both sides of the oval-shaped mounting holes, the bottom reinforcement iron of the box is a right-angled sheet structure, the lower side of the bottom reinforcement iron of the box is welded to the connecting block, the vertical side of the bottom reinforcement iron of the box is close to the transformer oil tank, and is welded to the side wall of the transformer oil tank.

[0016] The transformer foundation of the high seismic strength restorable caisson structure, the fixing transformer bolts connecting the caisson and the transformer oil tank are made of structural steel with strong ductility, and the fixing transformer bolts have an elastic potential energy of more than 27 joules.

[0017] The design idea of ​​the present invention is:

[0018] The caisson shell of the present invention is welded to the anchor bolts and buried in the foundation. The box body has a "U-shaped groove", which corresponds to the position of the through hole at the bottom of the transformer oil tank, and is connected and fixed to the transformer oil tank with fasteners. The fasteners are made of general structural steel with strong ductility, and high-strength steel fixing bolts are not used. In order to reduce the influence of shear force on the fasteners, a limit device is added to the design of this seismic system, so that these forces can pass through an intermediate medium to the bottom of the transformer oil tank. The present invention ensures that the transformer can still operate stably for a long time in a high-intensity earthquake environment with frequent earthquakes, avoids the problem of weakened seismic strength due to damage to the transformer fixings after an earthquake, and realizes the recoverability of seismic strength.

[0019] The advantages and beneficial effects of the present invention are:

[0020] 1. The present invention has been verified by simulation. Under the premise of not installing shock absorbers, it is ensured that the transformer foundation of the caisson structure can withstand a horizontal acceleration of 0.5g, that is, the intensity is between 9 and 10. This effectively solves the problem of high earthquake resistance of the transformer foundation, reduces the transformer design cost, and ensures the seismic performance of the product while reducing the complexity of transformer design.

[0021] 2. The caisson structure of the transformer foundation of the present invention allows the fasteners for fixing the transformer to be replaced regularly to restore the anti-seismic performance, thereby ensuring the long-term operation of the transformer.

[0022] 3. The fixing bolts connecting the caisson and the transformer of the present invention are made of general structural steel with strong ductility, and do not use high-endurance steel fixing bolts. In order to reduce the influence of shear force on the bolts, a limit device is added to the design of this seismic system, so that these forces can pass through the intermediate medium to the transformer base. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the front view of the installation of the caisson and the limit device of the present invention (each caisson has N mounting bolts, and the figure shows 2 as an example).

[0024] Figure 2 This is a top view of the installation of the caisson and the limiting device of the present invention.

[0025] Figure 3 It is an enlarged schematic diagram of the side view of the caisson installation of the present invention.

[0026] Figure 4 It is a schematic diagram of the side structure of the caisson of the present invention.

[0027] Figure 5 It is a schematic diagram of the top view structure of the caisson of the present invention.

[0028] Figure 6 The figure is a schematic diagram of the bottom structure of the transformer oil tank of the present invention.

[0029] In the figure: 1 transformer oil tank, 2 transformer oil tank bottom, 201 bottom reinforcement iron, 202 oval mounting hole, 203 connecting block, 3 limit device, 301 limit fixing plate, 4 caisson, 401 box upper cover plate, 402 box inner fixing plate, 403 upper rib plate, 404 box, 405 lower rib plate, 5 anchor bolts, 6 transformer fixing bolts, 7 caisson cover plate. DETAILED DESCRIPTION

[0030] The invention is further described below in conjunction with the accompanying drawings.

[0031] like Figure 1-Figure 6 As shown, the transformer foundation of the caisson structure with high seismic strength and recoverable in the present invention mainly includes: a transformer oil tank 1, a transformer oil tank bottom 2, a limit device 3, a caisson 4, anchor bolts 5, a transformer fixing bolt 6, a caisson cover plate 7, etc. The specific structure is as follows:

[0032] The transformer oil tank bottom 2 is arranged on the ground, and the caissons 4 are symmetrically distributed on both sides or around the transformer oil tank bottom 2. The bottom of the transformer oil tank bottom 2 is overlapped on the caisson 4, and each caisson 4 is connected and fixed to the transformer oil tank bottom 2 at the overlap by fixing the transformer bolts 6. The anchor bolts 5 located underground pass through the bottom of the caisson 4 and are welded to the caisson 4; the limit device 3 is arranged under the ground around the transformer oil tank bottom 2, and a limit fixing plate 301 is welded on the top of each limit device 3, and the limit fixing plate 301 is close to the four sides of the transformer oil tank bottom 2; the caisson cover plate 7 is used to cover the upper mouth of the caisson 4, and concrete is poured around the limit device 3, the caisson 4, and the anchor bolts 5 below the ground to form a transformer foundation.

[0033] After the concrete is poured, the transformer oil tank 1 is installed on the transformer oil tank bottom 2. While pouring the transformer foundation, the limit device 3 is poured. After the transformer oil tank 1 is fixed in place, a limit fixing plate 301 is welded on the limit device 3 to limit the displacement of the transformer oil tank 1 and the transformer oil tank bottom 2, and reduce the influence of shear force on the fixing transformer bolts 6.

[0034] like Figure 3-Figure 5 As shown, the caisson 4 is composed of a box upper cover plate 401, a box internal fixing plate 402, an upper rib plate 403, a box body 404, and a lower rib plate 405. The box body 404 is in the shape of a rectangular parallelepiped structure (or a cube structure, a four-sided pyramid structure with a trapezoidal cross section, etc.), and the box upper cover plate 401 is horizontally welded on one side of the top opening. There are one or more box upper cover plates 401. The box body 404 has a horizontal inner wall in the middle part thereof, and a box internal fixing plate 402 corresponding to the box upper cover plate 401 is horizontally welded. The corresponding box upper cover plate 401 and the box internal fixing plate 402 are welded to the box upper cover plate 401. A "U-shaped groove" is formed between 402 and the inner wall of the middle part of the box body 404, the edges between the upper cover plate 401 of the box body and the fixed plate 402 in the box body are welded by a vertical upper rib plate 403, and the fixed plate 402 in the box body and the bottom of the box body 404 are welded by a vertical lower rib plate 405 to increase the mechanical strength of the box body 404; the transformer fixing bolts 6 are passed through the corresponding upper cover plate 401 of the box body, the fixed plate 402 in the box body and the transformer oil tank bottom 2 overlapped on the caisson 4, so that the caisson 4 is connected and fixed to the transformer oil tank bottom 2.

[0035] Space is reserved on the other side of the top opening of the box body 404 to facilitate the installation of the transformer fixing bolts 6. If the transformer fixing bolts 6 are damaged, they can be taken out and replaced regularly to restore the seismic strength of the transformer foundation. Before pouring concrete, the space is covered with a caisson cover plate 7, and the caisson cover plate 7 is close to the upper cover plate 401 to prevent concrete from entering the box body 404. After adopting the "U-shaped groove" that runs through from top to bottom, the height of the caisson 4 is not restricted by the axial installation of the transformer fixing bolts 6 (such as: the transformer fixing bolts 6 are pushed in through the side notches of the box upper cover plate 401 and the fixed plate 402 in the box, and pass upward through the bottom 2 of the transformer oil tank, and are connected and fixed with nuts). There is no need to reserve installation space in the radial direction, and the height of the caisson can be reduced to increase its seismic resistance.

[0036] like Figure 2 , Figure 3 , Figure 6 As shown, the transformer oil tank bottom 2 is a rectangular steel plate with a thickness of 40 mm or more, and connecting blocks 203 are symmetrically arranged on both sides or all around. The connecting blocks 203 correspond to the caisson 4 one by one. The transformer oil tank bottom 2 is overlapped on the upper cover plate 401 of the caisson 4 through the connecting blocks 203. The connecting blocks 203 are provided with oval-shaped mounting holes 202 for the fixing transformer bolts 6 to pass through. The two edges and the middle of the upper surface of the connecting block 203 are provided with box bottom reinforcement irons 201. The box bottom reinforcement irons 201 are respectively located between and on both sides of the oval-shaped mounting holes 202. The box bottom reinforcement irons 201 are right-angled sheet structures. The lower side of the box bottom reinforcement irons 201 is welded to the connecting blocks 203, and the vertical sides of the box bottom reinforcement irons 201 are close to the transformer oil tank 1 and welded to the side walls of the transformer oil tank 1.

[0037] The fixing transformer bolts 6 connecting the caisson 4 and the transformer oil tank 1 are made of general structural steel with strong ductility, and high-strength steel fixing bolts are not used. In order to reduce the influence of shear force on the fasteners, a limit device 3 is added to the design of this seismic system, so that these forces can pass through the intermediate medium to the bottom 2 of the transformer oil tank, and the fixing transformer bolts 6 should have an elastic potential energy of more than 27 joules.

[0038] The design scheme of the present invention uses technical software modeling to analyze and design the structure, and analyze and select the bolt material characteristics. According to the calculation results, all technical parameters can reach the intensity between level 9 and level 10. At the same time, the structural form ensures that the transformer can still operate stably for a long time in an environment with high-intensity earthquakes, avoids the problem of weakened seismic strength due to damage to the transformer fixing parts after an earthquake, and realizes the recoverability of seismic strength.

Claims

1. A transformer foundation with a high seismic strength and restorable caisson structure, characterized in that: The transformer foundation includes: transformer oil tank bottom, limit device, caisson, anchor bolts, and transformer fixing bolts. The specific structure is as follows: The bottom of the transformer oil tank is set on the ground, and the caissons are symmetrically distributed on both sides or around the bottom of the transformer oil tank. The bottom of the transformer oil tank is overlapped on the caisson, and each caisson is fixed to the overlap of the transformer oil tank bottom by fixing the transformer bolts. The anchor bolts located underground pass through the bottom of the caisson and are welded to the caisson; the limit device is set under the ground around the bottom of the transformer oil tank, and a limit fixing plate is set on the top of each limit device, and the limit fixing plate is close to the four sides of the bottom of the transformer oil tank; The caisson cover plate covers the upper opening of the caisson, and concrete is poured around the limit device, caisson, and anchor bolts below the ground to form the transformer foundation; The caisson is composed of a box upper cover plate, a box inner fixed plate, an upper rib plate, a box body, and a lower rib plate. The box upper cover plate is horizontally welded on one side of the box top opening. There are one or more box upper covers. The box inner fixed plates corresponding to the box upper cover plate are horizontally welded on the middle inner wall of the box body. A "U-shaped groove" is formed between the corresponding box upper cover plate, the box inner fixed plate and the middle inner wall of the box body. The edges between the box upper cover plate and the box inner fixed plate are welded by a vertical upper rib plate, and the box inner fixed plate and the bottom of the box body are welded by a vertical lower rib plate. The transformer fixing bolts are penetrated through the corresponding box upper cover plate, the box inner fixed plate and the transformer oil tank bottom overlapped on the caisson, so that the caisson is connected and fixed to the transformer oil tank bottom.

2. The transformer foundation of the high seismic strength restorable caisson structure according to claim 1, characterized in that: After the concrete is poured, the transformer oil tank is installed on the bottom of the transformer oil tank, and a limiting fixing plate is welded on the limiting device to limit the displacement of the transformer oil tank and the bottom of the transformer oil tank.

3. The transformer foundation of the high seismic strength restorable caisson structure according to claim 1, characterized in that: A space is reserved on the other side of the top opening of the box body for installing the bolts that fix the transformer.

4. The transformer foundation of the high seismic strength restorable caisson structure according to claim 1, characterized in that: The bottom of the transformer oil tank is a rectangular steel plate with connecting blocks symmetrically arranged on both sides or all around. The connecting blocks correspond to the caisson one by one. The bottom of the transformer oil tank is overlapped with the upper cover plate of the caisson through the connecting blocks. The connecting blocks are provided with oblong mounting holes for the bolts for fixing the transformer to pass through. The bottom reinforcement irons are arranged on the two edges and the middle of the upper surface of the connecting blocks.

5. The transformer foundation of the high seismic strength restorable caisson structure according to claim 4, characterized in that: The box bottom reinforcement iron is respectively located between and on both sides of the oval mounting holes. The box bottom reinforcement iron is a right-angled sheet structure. The lower side of the box bottom reinforcement iron is welded to the connecting block. The vertical side of the box bottom reinforcement iron is close to the transformer oil tank and welded to the side wall of the transformer oil tank.

6. The transformer foundation of the high seismic strength restorable caisson structure according to claim 1, characterized in that: The transformer fixing bolts connecting the caisson and the transformer oil tank are made of structural steel with strong ductility, and the transformer fixing bolts have an elastic potential energy of more than 27 joules.

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