Multi-load foundation structure of transformer substation in soft soil area

Abstract

The invention discloses a soft soil area transformer substation multi-load foundation structure which comprises pipe pile bearing platforms, prestressed pipe piles and integrally-arranged beam plate type rafts, and the multiple pipe pile bearing platforms are arranged at the positions, corresponding to an accident oil pool area, a road cable trench area, a power distribution building area and a main transformer area, below the beam plate type rafts. Two vertically-arranged prestressed pipe piles are connected to the lower portion of each pipe pile bearing platform corresponding to the accident oil pool area, two vertically-arranged prestressed pipe piles are connected to the lower portion of each pipe pile bearing platform corresponding to the road cable trench area, and 3-8 prestressed pipe piles are connected to the lower portion of each pipe pile bearing platform corresponding to the power distribution building area according to the load difference. And six pre-stressed pipe piles which are vertically arranged are connected below each pipe pile bearing platform corresponding to the main transformer area. Continuous load transmission and overall stress of the foundation structure can be achieved, the problem that differential settlement of all areas is too large is effectively solved, the structural durability is improved, the local stress concentration risk is reduced, and the bearing reliability is improved.

Description

Technical Field

[0001] This invention relates to the field of building technology, and in particular to a multi-load foundation structure for a substation in a soft soil area. Background Technology

[0002] For substations built in areas of deep soft soil, the current industry mainly adopts a separate technical solution for foundation treatment and design: for core structures such as distribution buildings and main transformers, a "prestressed pipe pile + independent pile cap + frame column" structure is used; for ancillary facilities such as roads, cable trenches, and emergency oil tanks, a "cement mixing pile + crushed stone cushion" treatment scheme is generally used, with the mixing piles and soft soil forming a composite foundation to bear the load. However, this separate design results in significant differences in stiffness and bearing mechanisms between the core structures (pipe pile foundation, settlement usually ≤15mm) and the ancillary facilities (mixing pile composite foundation, settlement can reach 30-50mm). During operation, the risk of differential settlement in different areas is high, leading to problems such as "cracking at the junction of buildings and roads", "deformation of cable trenches leading to pipeline damage", and "uneven settlement of emergency oil tanks causing leakage". In addition, the overall stress coordination between the core structures and ancillary facilities is poor, and the stress cannot be distributed, which easily leads to stress concentration in local areas of the foundation and damage. Summary of the Invention

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a multi-load foundation structure for substations in soft soil areas, which can achieve continuous load transfer and overall stress distribution, effectively solve the problem of excessive differential settlement in different areas, improve structural durability, reduce the risk of local stress concentration, and enhance load-bearing reliability.

[0004] According to an embodiment of the present invention, a multi-load foundation structure for a substation in a soft soil area includes pipe pile caps, prestressed pipe piles, and an integrally formed beam-slab raft slab. The area above the beam-slab raft slab includes the substation's emergency oil tank area, road and cable trench area, power distribution building area, and main transformer area. Below the beam-slab raft slab, multiple pipe pile caps are arranged at positions corresponding to the emergency oil tank area, road and cable trench area, power distribution building area, and main transformer area. Each pipe pile cap corresponding to the emergency oil tank area is connected to two vertically arranged prestressed pipe piles. Each pipe pile cap corresponding to the road and cable trench area is connected to two vertically arranged prestressed pipe piles. Each pipe pile cap corresponding to the power distribution building area is connected to three to eight prestressed pipe piles according to load differences. Each pipe pile cap corresponding to the main transformer area is connected to six vertically arranged prestressed pipe piles. The length of each prestressed pipe pile is greater than 30 meters to penetrate the soft soil layer and reach the dense bearing layer.

[0005] The multi-load foundation structure of the substation in soft soil area according to the embodiments of the present invention has at least the following beneficial effects: the beam-slab raft foundation is continuous throughout the entire area, so all loads in the accident oil pool area, road cable trench area, power distribution building area and main transformer area can be uniformly transferred to the beam-slab raft foundation, and then distributed from the beam-slab raft foundation to the pipe pile cap below, and finally distributed from the pipe pile cap to each prestressed pipe pile that directly reaches the dense bearing layer, thereby realizing continuous load transfer and overall stress. On this basis, the number of prestressed pipe piles connected by the pipe pile cap is set according to the load difference of each area, and the rigidity of the beam-slab raft foundation itself can significantly reduce the settlement difference between areas, effectively solve the problem of excessive differential settlement between areas, and thus completely avoid problems such as "cracks at the joint, pipeline damage, and oil pool leakage", improving structural durability. At the same time, the vibration load of the main transformer area and the vehicle traffic load of the road cable trench area can be evenly transferred to the surrounding prestressed pipe piles through the beam-slab raft foundation, reducing the risk of local stress concentration and improving the bearing reliability.

[0006] According to some embodiments of the present invention, the beam-slab raft slab is composed of a raft slab body integrally cast with reinforced concrete and a grid-like distribution of ground beams. The ground beams are located on the lower side of the raft slab body, and all the pipe pile caps are connected to the ground beams. Adjacent pipe piles are supported by longitudinal reinforcement bars in the ground beams.

[0007] According to some embodiments of the present invention, the thickness of the raft slab is designed according to the load differences of each zone, including the road cable trench zone, the emergency oil tank zone, the power distribution building zone, and the main transformer zone.

[0008] According to some embodiments of the present invention, the raft slab thickness in the accident oil pool area is 400 mm, the raft slab thickness in the main transformer area is 250 mm, the raft slab thickness in the power distribution building area is 150-250 mm, and the raft slab thickness in the road cable trench area is 180 mm.

[0009] According to some embodiments of the present invention, the beam-slab raft slab in all regions adopts double-layer bidirectional reinforcement.

[0010] According to some embodiments of the present invention, the prestressed pipe pile is a PHC pipe pile with a diameter of 500mm, using C80 concrete, and the vertical bearing capacity of a single pile is ≥1800kN.

[0011] According to some embodiments of the present invention, the prestressed pipe pile is provided with a post-grouting layer for solidifying soft soil on the pile side.

[0012] According to some embodiments of the present invention, a crushed stone-geogrid composite cushion layer is provided between the pipe pile cap and the top of the prestressed pipe pile.

[0013] According to some embodiments of the present invention, a prefabricated buckling restraint brace is connected between two adjacent pipe pile caps, and a reinforced concrete connection is cast between the middle part of the buckling restraint brace and the ground beam.

[0014] According to some embodiments of the present invention, the construction method is as follows: first, multiple static pressure pile drivers are used to construct all the prestressed pipe piles in sections and simultaneously, and then the pipe pile cap and the beam-slab raft slab are constructed.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a basic structural elevation view of the multi-load foundation structure of a substation in a soft soil area according to an embodiment of the present invention. Figure 2 for Figure 1 The diagram shows the layout of pipe pile caps and prestressed pipe piles in various areas of the multi-load foundation structure of a substation in a soft soil area. Figure 3 for Figure 2 A schematic diagram showing the configuration of the number of central pipe pile caps and prestressed pipe piles; Figure 4 This is a schematic diagram of the seismic optimization structure of a multi-load foundation structure for a substation in a soft soil area, according to an embodiment of the present invention.

[0017] Figure label: Pipe pile cap 110, prestressed pipe pile 120, beam-slab raft slab 130, raft slab body 131, ground beam 132, reinforced concrete connection 133, post-grouting layer 210, crushed stone-geogrid composite cushion layer 220, buckling restraint brace 230, accident oil pool area 01, road cable trench area 02, power distribution building area 03, main transformer area 04. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0020] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0021] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0022] Reference Figures 1 to 3 According to an embodiment of the present invention, the multi-load foundation structure of a substation in a soft soil area includes pipe pile caps 110, prestressed pipe piles 120, and an integrally formed beam-slab raft slab 130. The area above the beam-slab raft slab 130 includes an emergency oil tank area 01, a road and cable trench area 02, a power distribution building area 03, and a main transformer area 04 of the substation. Below the beam-slab raft slab 130, multiple pipe pile caps 110 are arranged at positions corresponding to the emergency oil tank area 01, the road and cable trench area 02, the power distribution building area 03, and the main transformer area 04. Each pipe pile cap corresponding to the emergency oil tank area 01... Each 110 is connected to two vertically installed prestressed pipe piles 120. Corresponding to the road cable trench area 02, each pipe pile cap 110 is connected to two vertically installed prestressed pipe piles 120. Corresponding to the power distribution building area 03, each pipe pile cap 110 is connected to three to eight prestressed pipe piles 120 depending on the load difference. Corresponding to the main transformer area 04, each pipe pile cap 110 is connected to six vertically installed prestressed pipe piles 120. The length of each prestressed pipe pile 120 is greater than 30 meters to penetrate the soft soil layer and reach the dense bearing layer.

[0023] Among them, the road and cable trench area 02 is used to set up roads and cable trenches, and it is distributed in a ring shape; the accident oil tank area 01 is used to set up an accident oil tank, and the accident oil tank area 01 is located inside the road and cable trench area 02; the power distribution building area 03 is used to set up a power distribution building, and the power distribution building area 03 is located inside the road and cable trench area 02; and the main transformer area 04 is used to set up a main transformer room, and the main transformer area 04 is located inside the road and cable trench area 02 and next to the accident oil tank area 01.

[0024] Among them, "dense bearing layer" is a reasonable and commonly used descriptive term in the construction industry. The bearing layer refers to the soil layer that directly bears the foundation load and belongs to the foundation layer (corresponding to the underlying layer) classified according to engineering function. "Dense" refers to the physical state (compactness) of the soil and belongs to the state level classified according to mechanical properties (for example, the compactness of sand is divided into four levels: loose, slightly dense, medium dense, and dense). The combination of "dense bearing layer" is essentially a description of a soil layer that simultaneously meets the requirements of "dense state" and "bearing layer function", such as "dense medium sand bearing layer" or "dense crushed stone bearing layer".

[0025] In this invention, the beam-slab raft foundation 130 is continuous throughout the entire area. Therefore, all loads from the accident oil tank area 01, the road cable trench area 02, the power distribution building area 03, and the main transformer area 04 can be uniformly transferred to the beam-slab raft foundation 130, and then distributed from the beam-slab raft foundation 130 to the lower pipe pile cap 110, and finally from the pipe pile cap 110 to each prestressed pipe pile 120 that directly reaches the compacted bearing layer. This achieves continuous load transfer and overall stress distribution. Based on this, the number of prestressed pipe piles 120 connected through the pipe pile cap 110... Based on the differentiated load settings for each area and the inherent stiffness of the beam-slab raft slab 130, the settlement difference between areas can be significantly reduced, effectively solving the problem of excessive differential settlement between areas. This completely avoids problems such as "cracks at joints, pipeline damage, and oil pool leakage," improving structural durability. At the same time, the vibration load of the main transformer area 04 and the vehicle traffic load of the road cable trench area 02 can be evenly transferred to the surrounding prestressed pipe piles 120 through the beam-slab raft slab 130, reducing the risk of local stress concentration and improving load-bearing reliability.

[0026] Reference Figure 1 According to some embodiments of the present invention, the beam-slab raft slab 130 is composed of a raft slab body 131 integrally cast with reinforced concrete and a grid-like distribution of ground beams 132. The ground beams 132 are located below the raft slab body 131, and all the pipe pile caps 110 are connected to the ground beams 132. Adjacent pipe piles share the load collaboratively through the long longitudinal reinforcement within the ground beams 132, thereby achieving load transfer and dispersion, forming a continuous load transfer and overall force-bearing system of pipe piles + caps + beam-slab raft slab 130 throughout the entire area. The ground beams 132 are grid-like beam structures formed by the intersecting connection of multiple horizontal beams and multiple longitudinal beams. Both the horizontal and longitudinal beams have long longitudinal reinforcement and short horizontal reinforcement. The long longitudinal reinforcement refers to long steel bars along the length of the horizontal or longitudinal beam.

[0027] According to some embodiments of the present invention, the thickness of the raft slab 131 is designed according to the load differences of each area, including the road cable trench area 02, the accident oil tank area 01, the power distribution building area 03, and the main transformer area 04, so that the load-bearing capacity of the raft slab 131 can be adapted to the load conditions and usage requirements of each area, while reducing the overall weight of the raft slab 131.

[0028] According to some embodiments of the present invention, the raft foundation 131 located in the accident oil pool area 01 has a thickness of 400mm to meet the requirements of leakage prevention and waterproofing of the accident oil pool area 01; the raft foundation 131 located in the main transformer area 04 has a thickness of 250mm to meet the load bearing requirements; the raft foundation 131 located in the power distribution building area 03 has a thickness of 150~250mm to meet the load bearing requirements; and the raft foundation 131 located in the road cable trench area 02 has a thickness of 180mm to meet the load bearing requirements.

[0029] According to some embodiments of the present invention, the beam-slab raft slab 130 in all areas adopts double-layer bidirectional reinforcement to ensure the load-bearing capacity and strength of the beam-slab raft slab 130.

[0030] According to some embodiments of the present invention, the prestressed pipe pile 120 is a 500mm diameter PHC pipe pile, made of C80 concrete, with a single pile vertical bearing capacity ≥1800kN. Therefore, the prestressed pipe pile 120 has sufficient bearing capacity, strength, and stiffness. PHC pipe pile, namely prestressed high-strength concrete pipe pile, is a hollow cylindrical pile foundation component prefabricated in a factory and cured under high pressure steam. It is driven on site using static pressure method or hammer driving method, without the need for on-site casting and curing as with bored piles. The construction period in soft soil areas is only 1 / 3 to 1 / 2 of that of traditional pile foundations, and the pile driving process causes little disturbance to the soft soil, making construction efficient and convenient.

[0031] Reference Figure 4 According to some embodiments of the present invention, a post-grouting layer 210 for solidifying soft soil is provided on the side of the prestressed pipe pile 120. The solidification effect of the post-grouting layer 210 on the soft soil around the pile, combined with the soft soil compaction effect and anti-liquefaction ability of the PHC pipe pile, effectively enhances the pile-soil synergy, thereby improving the bearing capacity stability during earthquakes.

[0032] Reference Figure 4 According to some embodiments of the present invention, a crushed stone-geogrid composite cushion layer 220 is provided between the top of the pipe pile cap 110 and the prestressed pipe pile 120. The crushed stone-geogrid composite cushion layer 220 is composed of a crushed stone layer and a geogrid. The crushed stone layer can dissipate the pressure of liquefied pore water, while the geogrid enhances the integrity of the cushion layer, reduces uneven settlement of the cap during earthquakes, and also buffers seismic waves. The range of the crushed stone-geogrid composite cushion layer 220 coincides with the range of the post-grouting layer 210, and the crushed stone-geogrid composite cushion layer 220 abuts against the post-grouting layer 210. Therefore, the crushed stone-geogrid composite cushion layer 220 and the post-grouting layer 210 can work together synergistically.

[0033] Reference Figure 4According to some embodiments of the present invention, a prefabricated buckling-restrained brace 230 is connected between two adjacent pipe pile caps 110, and a reinforced concrete connection 133 is cast between the middle of the buckling-restrained brace 230 and the ground beam 132. During an earthquake, the buckling-restrained brace 230 itself can yield before the pipe pile cap 110, dissipating energy through the plastic deformation of the steel, while providing horizontal lateral stiffness and limiting the horizontal displacement of the pipe pile cap 110. At the same time, an additional connection can be formed between two adjacent pipe pile caps 110 and the ground beam 132 through the buckling-restrained brace 230, forming a suspended support for the beam-slab raft slab 130, which can effectively improve the seismic performance of the foundation structure. The buckling restraint brace 230 includes a core material and a restraint member covering the core material. The core material is made of low yield point steel with an I-shaped or cross-shaped cross section or HRB400E seismic-resistant steel reinforcement. The restraint member is made of concrete, steel-concrete composite tube, or steel plate sleeve. The space between the core material and the restraint member is filled with mortar, foam, or rubber pads. The restraint member only undertakes the "buckling resistance" function and does not participate in energy consumption. The core material only bears axial force and does not bear bending moment, ensuring stable energy dissipation during earthquakes.

[0034] According to some embodiments of the present invention, the construction method of the multi-load foundation structure for substations in soft soil areas provided by the present invention is as follows: first, multiple static pressure pile drivers are used to simultaneously construct all prestressed pipe piles 120 in sections, followed by the construction of pipe pile caps 110 and beam-slab raft slabs 130. The present invention allows for simultaneous construction of the entire area, eliminating the need for sectioned construction and multiple curing processes, shortening the total construction period to 30-40 days, which is more than 50% less than the 60-90 days of existing technologies. Simultaneous construction across the entire area eliminates construction joints, saving the need for subsequent waterproofing procedures, further reducing construction complexity and cost. The pipe pile caps 110 and beam-slab raft slabs 130 can be integrally cast, ensuring connection strength and reducing construction stages.

[0035] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A multi-load foundation structure for a substation in a soft soil area, characterized in that, The system includes pipe pile caps (110), prestressed pipe piles (120), and an integrated beam-slab raft slab (130). The area above the beam-slab raft slab (130) includes the substation's emergency oil tank area (01), road cable trench area (02), power distribution building area (03), and main transformer area (04). Multiple pipe pile caps (110) are arranged below the beam-slab raft slab (130) at positions corresponding to the emergency oil tank area (01), road cable trench area (02), power distribution building area (03), and main transformer area (04). Each pipe pile cap (110) corresponding to the emergency oil tank area (01) is connected to a... Two vertically arranged prestressed pipe piles (120) are connected to each pipe pile cap (110) in the road cable trench area (02). Two vertically arranged prestressed pipe piles (120) are connected to each pipe pile cap (110) in the power distribution building area (03). Three to eight prestressed pipe piles (120) are connected to each pipe pile cap (110) in the power distribution building area (03) according to the load difference. Six vertically arranged prestressed pipe piles (120) are connected to each pipe pile cap (110) in the main transformer area (04). The length of each prestressed pipe pile (120) is greater than 30 meters to penetrate the soft soil layer and reach the dense bearing layer.

2. The multi-load foundation structure for a substation in a soft soil area according to claim 1, characterized in that, The beam-slab raft slab (130) is composed of a raft slab body (131) formed by integral casting of reinforced concrete and a grid-like distribution of ground beams (132). The ground beams (132) are located on the lower side of the raft slab body (131). All the pipe pile caps (110) are connected to the ground beams (132). Two adjacent pipe piles are supported by the longitudinal reinforcement in the ground beams (132).

3. The multi-load foundation structure for a substation in a soft soil area according to claim 1, characterized in that, The thickness of the raft slab (131) is designed according to the load differences of each area, namely the road cable trench area (02), the accident oil pool area (01), the power distribution building area (03), and the main transformer area (04).

4. The multi-load foundation structure for a substation in a soft soil area according to claim 2, characterized in that, The thickness of the raft body (131) located in the accident oil pool area (01) is 400mm, the thickness of the raft body (131) located in the main transformer area (04) is 250mm, the thickness of the raft body (131) located in the power distribution building area (03) is 150~250mm, and the thickness of the raft body (131) located in the road cable trench area (02) is 180mm.

5. A multi-load foundation structure for a substation in a soft soil area according to claim 1, characterized in that, All beam-slab raft slabs (130) in all areas are reinforced with double-layer bidirectional reinforcement.

6. A multi-load foundation structure for a substation in a soft soil area according to claim 2, characterized in that, The prestressed pipe pile (120) is a PHC pipe pile with a diameter of 500mm, using C80 concrete, and the vertical bearing capacity of a single pile is ≥1800kN.

7. A multi-load foundation structure for a substation in a soft soil area according to claim 6, characterized in that, The prestressed pipe pile (120) has a post-grouting layer (210) on its side for solidifying soft soil.

8. A multi-load foundation structure for a substation in soft soil area according to claim 1, characterized in that, A crushed stone-geogrid composite cushion layer (220) is provided between the pile cap (110) and the top of the prestressed pipe pile (120).

9. A multi-load foundation structure for a substation in a soft soil area according to claim 2, characterized in that, A prefabricated buckling restraint brace (230) is connected between two adjacent pipe pile caps (110), and a reinforced concrete connection (133) is poured between the middle of the buckling restraint brace (230) and the ground beam (132).

10. A multi-load foundation structure for a substation in a soft soil area according to claim 1, characterized in that, The construction method is as follows: first, multiple static pressure pile drivers are used to construct all the prestressed pipe piles (120) in sections and simultaneously, and then the pipe pile cap (110) and the beam-slab raft slab (130) are constructed.

Images