A new type of foundation for a transmission line river-crossing tower

Abstract

The utility model discloses a novel transmission line river-crossing tower foundation relates to transmission line engineering technical field, it includes four independent foundation and three layers of link beam, three layers of link beam are arranged at four independent foundation between along vertical direction interval, for the whole reinforcement of four independent foundation and the stress synergy, every independent foundation all includes foundation bottom plate and foundation stand, and foundation bottom plate horizontal arrangement, its top and the bottom fixed connection of foundation stand, three layers of link beam include upper layer link beam, middle layer link beam and lower layer link beam, upper layer link beam is close to the bottom setting of iron tower tower leg, and middle layer link beam sets up in the middle position of foundation stand height direction, and the bottom of lower layer link beam is flush with the top of foundation bottom plate. The utility model scheme can adapt to the soft soil of river bank, and the whole stress synergy performance is good, can effectively resist water environment erosion, and the service life is long.

Description

Technical Field

[0001] This utility model relates to the field of power transmission line engineering technology, and in particular to a novel foundation for a power transmission line tower crossing a river. Background Technology

[0002] The river-crossing sections of power transmission lines are a crucial link in the power transmission network, and the performance of the river-crossing tower foundation, as the core structure supporting the transmission tower, directly determines the safety and stability of the line. Constructing river-crossing tower foundations in a riverside environment presents a dual core challenge: firstly, riverside soil, due to long-term immersion in river water, is generally soft and has low bearing capacity, making traditional foundations prone to uneven settlement, leading to tower tilting and even structural instability; secondly, the foundation columns are constantly exposed to river water immersion, water erosion, and seasonal freeze-thaw cycles, making the materials susceptible to corrosion and deterioration, significantly reducing durability, increasing maintenance costs, and posing significant safety hazards such as tower collapse.

[0003] Existing technologies have significant limitations in solutions for tower foundations spanning rivers. While monolithic foundation designs can ensure a certain degree of integrity, they are poorly adaptable to uneven riverbank foundations, and localized settlement can easily lead to overall foundation cracking. On the other hand, conventional independent foundation solutions lack effective connecting and reinforcing structures, resulting in isolated foundation units that are unable to work together to resist horizontal loads and water flow impacts, leading to insufficient stability in complex environments.

[0004] Therefore, there is an urgent need to design a cross-river tower foundation that can adapt to the soft soil along the river, improve the overall synergistic stress performance, effectively resist water erosion, and extend the service life. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a new type of transmission line cross-river tower foundation, which can adapt to the soft soil of the riverbank, has good overall coordinated stress performance, can effectively resist water environment erosion, and has a long service life.

[0006] The technical solution adopted by this utility model to solve its technical problem is: a new type of transmission line cross-river tower foundation, including 4 independent foundations and three layers of connecting beams; the 4 independent foundations are distributed in a rectangular shape, and each tower leg of the tower is connected to one independent foundation respectively; the three layers of connecting beams are arranged vertically at intervals between the 4 independent foundations to reinforce the 4 independent foundations as a whole and to cooperate in bearing the force.

[0007] Each of the aforementioned independent foundations includes a foundation base plate and a foundation column; the foundation base plate is horizontally arranged, its top is fixedly connected to the bottom of the foundation column, and the cross-sectional area of ​​the foundation base plate is larger than the cross-sectional area of ​​the foundation column.

[0008] The three-layer connecting beam includes an upper connecting beam, a middle connecting beam, and a lower connecting beam; the upper connecting beam is located near the bottom of the tower leg, and the distance between its top surface and the bottom of the tower leg is no more than 0.15m; the middle connecting beam is located at the middle of the foundation column height direction; the bottom of the lower connecting beam is flush with the top of the foundation slab.

[0009] Furthermore, the foundation slab is square or rectangular in shape and buried at a depth of not less than 6m; a concrete cushion layer is provided below the foundation slab, and the thickness of the concrete cushion layer is not less than 100mm.

[0010] Furthermore, the foundation column is made of corrosion-resistant concrete material with a permeability grade of not less than P8, and the outer surface of the foundation column is provided with an anti-corrosion coating, which is an epoxy asphalt paint coating.

[0011] Furthermore, a crash protection sleeve is installed at the part of the foundation column that comes into contact with the river water; the crash protection sleeve is made of steel and its interior is filled with an asphalt hemp fiber buffer layer.

[0012] Furthermore, the upper, middle, and lower connecting beams are all reinforced concrete structures; the interior of the upper, middle, and lower connecting beams is equipped with longitudinal reinforcing bars and stirrups, the diameter of the longitudinal reinforcing bars is not less than 16mm, and the spacing of the stirrups is not greater than 200mm.

[0013] Furthermore, the upper connecting beam is connected to the tower leg via a base plate and anchor bolts; the thickness of the base plate is determined based on stress calculations and is not less than 35mm; the anchor bolts are pre-embedded in the foundation column, with a diameter of not less than 36mm and a length of not less than 1500mm.

[0014] Furthermore, the surfaces of the upper, middle, and lower connecting beams are all provided with a waterproof coating, which is a polyurethane waterproof coating.

[0015] The beneficial effects of this utility model are:

[0016] 1. This utility model precisely addresses the challenges of soft soil along riverbanks through the coordinated design of four independent foundations and three-layer connecting beams. The independent foundations utilize an enlarged base plate area and a deeper burial depth to significantly increase the soil contact area, effectively dispersing the load and improving the anti-settlement capacity by more than 50% compared to traditional designs. The three-layer connecting beams have a clear division of labor: the upper layer transmits horizontal loads, the middle layer enhances lateral stiffness, and the lower layer disperses bottom stress, forming a spatial frame system. This enhances the overall anti-overturning moment and can stably resist complex loads such as strong winds and water flow impacts, ensuring that the transmission tower remains stable even when the foundation settles unevenly.

[0017] 2. To address the issue of river erosion, this application constructs a multi-layered protection system; the foundation columns are made of corrosion-resistant concrete with a permeability grade ≥ P8, coated with epoxy asphalt paint on the outside, forming a dual protection of material impermeability and surface isolation; the connecting beams are coated with polyurethane waterproof coating, which has a long service life against water erosion; steel anti-collision casings are installed in the water level fluctuation zone, filled with a buffer layer, which can absorb impact energy and reduce the water flow erosion rate. Combined with the selection of antifreeze concrete, it effectively resists freeze-thaw cycles and significantly extends the service life of the foundation.

[0018] 3. This scheme adopts a modular design, with four independent foundations that can be constructed simultaneously, reducing disturbance to the original soil of the riverbed. The connecting beams are connected by welding with pre-embedded steel bars, eliminating the need for complex processes and improving construction efficiency. Compared with monolithic foundations, the amount of concrete used is reduced, and steel consumption is lower, making it suitable for construction in complex sites. The multi-layered protection design reduces later maintenance costs, lowers the overall cost, and combines economy and convenience. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure after the embodiment of this utility model is connected to the tower body.

[0020] Figure 2 This is a three-dimensional structural schematic diagram of an embodiment of the present invention.

[0021] Figure 3 This is a side view of an embodiment of the present utility model.

[0022] Figure 4 This is a top view of an embodiment of the present utility model.

[0023] In the diagram: 1. Foundation slab; 2. Lower layer connecting beam; 3. Middle layer connecting beam; 4. Upper layer connecting beam; 5. Foundation column. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment takes a 220kV transmission line crossing a river as an example. The soil on both banks of the river crossing is soft clay, the groundwater level is high, and there is seasonal flooding. Based on the technical solution of the present invention, the foundation of the river-crossing tower is designed as follows:

[0025] Reference Figures 1 to 4 The novel transmission line tower foundation in this embodiment consists of four independent foundations and three layers of connecting beams. The four independent foundations are arranged in a rectangular pattern, with a distance of 8 meters between the long sides and 6 meters between the short sides. Each of the four independent foundations corresponds to one of the four legs of the tower. The three layers of connecting beams are spaced vertically between the four independent foundations, forming a spatial frame system for overall reinforcement.

[0026] Each independent foundation includes a foundation base plate 1 and a foundation column 5; the foundation base plate 1 is horizontally set, and its top is fixedly connected to the bottom of the foundation column 5, and the cross-sectional area of ​​the foundation base plate 1 is larger than the cross-sectional area of ​​the foundation column 5.

[0027] The foundation slab 1 is square or rectangular in shape, and its embedment depth is determined based on the bearing capacity of the riverbank soil and geological conditions, with a minimum embedment depth of 6m. A concrete cushion layer with a thickness of at least 100mm is placed beneath the foundation slab 1. The foundation slab 1 adopts an enlarged area design, which increases the contact area between the foundation and the soil, thereby improving the foundation's resistance to settlement. The embedment depth of the foundation slab 1, at least 6m, allows the foundation to penetrate into a relatively stable soil layer, reducing the risk of settlement due to soft surface soil. Simultaneously, the soil's own weight resists uplift forces, improving the foundation's resistance to overturning. The concrete cushion layer isolates pollutants, levels the base, improves the soil environment, diffuses loads, and plays a role in frost resistance and settlement prevention under special geological or climatic conditions.

[0028] In this embodiment, the foundation slab 1 adopts a square enlarged foundation with a side length of 4m, a thickness of 1.2m, and an embedment depth of 7m, extending 2m into the stable clay layer. The foundation slab 1 is cast with C35 concrete and equipped with a double-layer bidirectional steel mesh: the longitudinal reinforcement uses HRB400 grade steel bars with a diameter of 20mm and a spacing of 150mm; the transverse reinforcement has the same specifications as the longitudinal reinforcement, forming a grid-like stress system.

[0029] A 150mm thick C25 plain concrete cushion layer is set under the foundation slab 1. The cushion layer extends 100mm beyond the edge of the foundation slab 1 on each side, which serves to isolate groundwater, level the foundation, and diffuse the upper load.

[0030] Foundation column 5 is made of corrosion-resistant concrete with a permeability grade of at least P8. The outer surface of foundation column 5 is coated with an epoxy asphalt paint layer. The special corrosion-resistant concrete material used in foundation column 5 provides high permeability and frost resistance, effectively resisting river water seepage and freeze-thaw cycles. Furthermore, the anti-corrosion coating on the outer surface of foundation column 5 further enhances its corrosion resistance and extends its service life.

[0031] In this embodiment, the foundation column 5 has a square cross-section with a side length of 1.0m and a height of 10m, of which 3m is below ground level and 7m is above ground level. It is constructed using corrosion-resistant concrete with a permeability grade of P10 and a frost resistance grade of F200, determined based on the local winter freeze-thaw cycle count. A 2mm thick epoxy asphalt paint anti-corrosion coating is applied to the outside of the foundation column 5, applied in two layers. The second layer is applied after the first layer has dried, ensuring even coverage.

[0032] The longitudinal reinforcing bars inside the foundation column 5 are 16 HRB400 grade steel bars with a diameter of 25mm, evenly arranged around the perimeter of the cross section; the stirrups are HPB300 grade steel bars with a diameter of 12mm and a spacing of 150mm, and are densified to 100mm within a 2m range at the bottom and top of the column to enhance shear resistance.

[0033] The three-layer connecting beam system includes an upper connecting beam 4, a middle connecting beam 3, and a lower connecting beam 2. The upper connecting beam 4 is located near the bottom of the tower leg, with its top surface no more than 0.15m from the bottom of the tower leg. The middle connecting beam 3 is located at the midpoint of the foundation column 5 in the height direction. The bottom of the lower connecting beam 2 is flush with the top of the foundation slab 1. The upper connecting beam 4, the middle connecting beam 3, and the lower connecting beam 2 are all reinforced concrete structures with a cross-sectional dimension of no less than 0.25m wide × 0.4m high. The upper connecting beam 4, the middle connecting beam 3, and the lower connecting beam 2 are all internally equipped with longitudinal reinforcing bars and stirrups. The diameter of the longitudinal reinforcing bars is no less than 16mm, and the spacing of the stirrups is no more than 200mm.

[0034] In this embodiment, the lower connecting beam 2 has a cross-sectional dimension of 0.5m wide × 0.6m high, and is cast with C30 reinforced concrete. Internal longitudinal reinforcement includes: 6 HRB400 grade steel bars (22mm diameter) at the top and bottom of the beam; and HPB300 grade steel bars (10mm diameter) spaced at 150mm intervals, with the spacing increased to 100mm at both ends of the beam within a range of 1.5 times the beam height.

[0035] The lower connecting beam 2 is connected to the foundation column 5 via pre-embedded steel bars: HRB400 grade steel bars, 20mm in diameter, are pre-embedded in the column, extending 350mm beyond the column surface, and are welded to the connecting beam steel bars. The weld length is 10 times the diameter of the steel bars to ensure effective force transfer. The main function of the lower connecting beam 2 is to effectively disperse the stress at the bottom of the foundation. Due to the uneven soil conditions along the riverbank, stress concentration is prone to occur in the foundation when under load. The lower connecting beam 2 redistributes the stress at the bottom of the foundation, allowing the stress to be transferred more evenly to the soil, reducing excessive stress on local soil areas, and further improving the stability and bearing capacity of the foundation.

[0036] The cross-sectional dimensions of the intermediate-level connecting beam 3 are the same as those of the lower-level connecting beam 2, and the materials and reinforcement are the same. At the junction of the intermediate-level connecting beam 3 and the foundation column 5, a vertical haunch design is adopted, with a haunch height of 0.3m and a length of 0.5m. Four diagonal reinforcing bars with a diameter of 16mm are added inside to enhance the shear resistance of the joint. The intermediate-level connecting beam 3 is mainly used to enhance the foundation's resistance to lateral displacement in the horizontal direction. Under horizontal loads such as river scouring and earthquakes, the intermediate-level connecting beam 3 can limit the relative displacement between independent foundations, enabling the four independent foundations to work together to resist horizontal forces, thereby improving the overall stiffness and stability of the foundation structure.

[0037] The top surface of the upper connecting beam 4 is 0.1m away from the bottom of the tower leg. Its cross-sectional dimensions are the same as the lower connecting beam 2, and its material and reinforcement are identical. The connection method between the upper connecting beam 4 and the foundation column 5 is the same as that of the middle connecting beam 3, and additional reinforcing bars are added at the connection node with the tower leg. The upper connecting beam 4 primarily bears the transmission of horizontal loads from the tower. When the transmission tower is subjected to horizontal loads such as wind force and conductor tension, the upper connecting beam 4 can effectively transfer these loads to each independent foundation, allowing the four independent foundations to share the load and improving the overall stability of the foundation.

[0038] After the three-layer connecting beam is poured and cured, a 2mm thick polyurethane waterproof coating is applied to the surface in two coats. The coating area includes the top surface, sides and inside corners where it connects to the columns, forming a complete waterproof system.

[0039] The upper connecting beam 4 is connected to the tower leg by the tower foot plate and anchor bolts; the thickness of the tower foot plate is determined according to the stress calculation and is not less than 35mm; the anchor bolts are embedded in the foundation column 5, with a diameter of not less than 36mm and a length of not less than 1500mm.

[0040] In this embodiment, the tower foot base plate is made of Q355 steel plate with a thickness of 80mm and dimensions of 1.2m × 1.2m. The anchor bolts are made of 40Cr alloy structural steel with a diameter of 50mm and a length of 2500mm, totaling 8 bolts, evenly distributed along the perimeter of the tower foot base plate. The anchor bolts are pre-embedded in the top of the foundation column 5 to a depth of 1800mm, and are tied and fixed to the column reinforcement, forming an integral load-bearing structure after pouring.

[0041] A steel crash barrier is installed around the part of the foundation column 5 that comes into contact with the river water. The barrier is made of Q235 steel plate with a wall thickness of 10mm, and its diameter is 200mm larger than the diagonal of the cross-section of the foundation column 5. An asphalt-impregnated hemp fiber buffer layer is filled between the barrier and the foundation column 5. The bottom of the barrier is welded and fixed to the top surface of the foundation base plate 1, and the top is 1m above the highest flood level, effectively reducing damage to the foundation column 5 from ship collisions and water erosion.

[0042] This embodiment, through the specific structural design described above, can adapt to the soft clay environment along the riverbank and the conditions of river water immersion, significantly improving the stability and durability of the cross-river tower foundation. Those skilled in the art can adjust the above dimensions and material parameters according to the geological conditions and tower parameters of the actual project; as long as they conform to the technical features defined in the claims, they fall within the protection scope of this utility model.

Claims

1. A novel foundation for a transmission line tower crossing a river, characterized in that: It includes four independent foundations and three layers of connecting beams; the four independent foundations are arranged in a rectangular shape, and each leg of the tower is connected to one independent foundation; the three layers of connecting beams are arranged vertically between the four independent foundations to reinforce the four independent foundations as a whole and to share the load together. Each of the independent foundations includes a foundation plate (1) and a foundation column (5); the foundation plate (1) is horizontally arranged, its top is fixedly connected to the bottom of the foundation column (5), and the cross-sectional area of ​​the foundation plate (1) is greater than the cross-sectional area of ​​the foundation column (5); The three-layer connecting beam includes an upper connecting beam (4), a middle connecting beam (3), and a lower connecting beam (2); the upper connecting beam (4) is set near the bottom of the tower leg, and the distance between its top surface and the bottom of the tower leg is no more than 0.15m; the middle connecting beam (3) is set at the middle position in the height direction of the foundation column (5); the bottom of the lower connecting beam (2) is flush with the top of the foundation plate (1).

2. The novel transmission line river-crossing tower foundation according to claim 1, characterized in that, The foundation plate (1) is square or rectangular in shape and buried at a depth of not less than 6m; a concrete cushion layer is provided below the foundation plate (1) and the thickness of the concrete cushion layer is not less than 100mm.

3. The novel transmission line river-crossing tower foundation according to claim 1, characterized in that: The foundation column (5) is made of corrosion-resistant concrete material, and the impermeability grade of the corrosion-resistant concrete material is not lower than P8. The outer surface of the foundation column (5) is provided with an anti-corrosion coating, which is an epoxy asphalt paint coating.

4. The novel transmission line river-crossing tower foundation according to claim 3, characterized in that: A crash protection sleeve is installed at the part of the foundation column (5) that comes into contact with the river water; the crash protection sleeve is made of steel and its interior is filled with an asphalt hemp fiber buffer layer.

5. The novel transmission line river-crossing tower foundation according to claim 4, characterized in that: The upper connecting beam (4), the middle connecting beam (3) and the lower connecting beam (2) are all reinforced concrete structures; the upper connecting beam (4), the middle connecting beam (3) and the lower connecting beam (2) are all equipped with longitudinal reinforcing bars and stirrups, the diameter of the longitudinal reinforcing bars is not less than 16mm and the spacing of the stirrups is not greater than 200mm.

6. The novel transmission line river-crossing tower foundation according to claim 5, characterized in that: The upper connecting beam (4) is connected to the tower leg by the tower foot plate and anchor bolts; the thickness of the tower foot plate is determined according to the stress calculation and is not less than 35mm; the anchor bolts are embedded in the foundation column (5) with a diameter of not less than 36mm and a length of not less than 1500mm.

7. The novel transmission line river-crossing tower foundation according to claim 6, characterized in that: The surfaces of the upper connecting beam (4), the middle connecting beam (3) and the lower connecting beam (2) are all provided with a waterproof coating, which is a polyurethane waterproof coating.

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