Concrete-filled steel tube pier column foot anti-rockfall structure and construction method thereof

Abstract

The invention relates to a concrete-filled steel tube pier column foot rockfall prevention structure and a construction method, and belongs to the technical field of bridges. A concrete filled steel tube pier column foot rockfall prevention structure is characterized by comprising a layered bearing platform structure, a column foot pre-embedded component assembly, a column foot steel structure assembly, outer wrapped concrete and a fine adjustment positioning assembly. The layered bearing platform structure is composed of a lower bearing platform and an additional platform, the lower bearing platform is located below the ground, and the additional platform is located above the lower bearing platform, exposed out of the ground and used for preventing falling stone impact. The layered bearing platform and the encased concrete are arranged, so that the size is reduced, the light weight of the concrete-filled steel tube structure is adapted, and compared with a traditional single anti-collision assembly (such as a cushion), the size is effectively reduced, and the characteristic of light dead weight of the concrete-filled steel tube is adapted.

Description

Technical Field

[0001] The present invention relates to a steel tube concrete pier column foot anti-rockfall structure integrating an anti-collision function into the pier structure and a construction method thereof, belonging to the technical field of bridge engineering. Background Art

[0002] Concrete-filled steel tube structures offer advantages such as light weight, high strength, formwork-free construction, and minimal site requirements. These advantages significantly reduce the use of concrete, steel, and other materials. Concrete-filled steel tube composite high piers are lightweight, reduce the number of pile foundations, and minimize excavation and slope protection work for bridge foundations on steep slopes. Furthermore, they facilitate construction, reducing project costs and offering significant economic benefits. They represent a key technical approach to addressing the challenges of high pier construction on mountainous railways and are of great significance for promoting the development of railway bridge technology in mountainous areas.

[0003] Traditional direct collision avoidance designs for bridges (such as external steel plates and reinforced concrete) are prone to fatigue cracking due to stress concentration and are prone to deformation and failure after long-term impact from falling rocks. Furthermore, they require thickening bridge piers or adding heavy protective layers, which increases the deadweight of the structure. These structures are not suitable for areas with limited space, such as steep slopes in mountainous areas. Indirect collision avoidance structures also have certain drawbacks. The first is the high cost, requiring the independent construction of collision avoidance piers or buffer barriers, which increases material and construction costs by more than 30%. Furthermore, indirect collision avoidance requires additional foundation excavation and occupies a large space, making construction difficult in narrow mountainous areas or near existing traffic lines. Furthermore, insufficient control over the trajectory of falling rocks may leave blind spots for impact. Summary of the Invention

[0004] In response to the problems existing in existing bridge anti-collision technology, the present invention provides a rockfall prevention structure and construction method with simple structure, low cost and good durability. The structure is suitable for steel tube concrete bridge piers, especially in mountainous areas that are easily affected by rolling stones or debris flows.

[0005] The construction method of the concrete-filled steel tube bridge pier column foot anti-rockfall structure of the present invention comprises the following steps:

[0006] S1. Cast the lower cap and form a flat column foot embedded plate on the upper surface of the lower cap. Multiple anchor bolts are exposed on the upper side of the column foot embedded plate and are evenly distributed.

[0007] Hoisting and fine-tuning of the column foot steel structure: install leveling nuts on the side of each anchor bolt exposed from the column foot annular pre-embedded steel plate, then place leveling washers on the leveling nuts, hoist the column foot steel structure components, make the openings of the evenly opened column foot pressure-bearing base plate initially aligned with the anchor bolts, and seat them on the leveling washers, use wedge blocks to insert between the column foot pressure-bearing base plate and the column foot annular pre-embedded steel plate to adjust the horizontality of the column foot pressure-bearing base plate, adjust the elevation of the leveling nuts until the leveling washers are close to the column foot pressure-bearing base plate, install a detachable steel formwork surrounding the column foot annular pre-embedded steel plate on the upper surface of the lower pedestal and set a rubber leak-proof strip, use gravity grouting to cast the area between the column foot pressure-bearing base plate and the column foot annular pre-embedded steel plate, install fasteners outside the anchor bolts exposed on the upper surface of the column foot pressure-bearing base plate, and tighten the column foot pressure-bearing base plate;

[0008] S3. Pouring concrete for the additional platform and steel pipe: Tie the additional platform steel bars outside the column base steel structure components, and pour the additional platform concrete and concrete inside the steel pipe pier;

[0009] S4. External concrete construction: Tie the external concrete reinforcement, set a waterproof layer on the edge of the upper bearing plate, and pour external concrete on the steel pipe pier above the waterproof layer;

[0010] The column base steel structure assembly includes a steel pipe pier, shear nails are evenly welded on the outer periphery of the steel pipe pier, and the lower part of the steel pipe pier is provided with a column base pressure-bearing base plate located at the lower end and an upper pressure-bearing plate close to the lower end, wherein the opening diameter of the column base pressure-bearing base plate is larger than the anchor bolt.

[0011] The column foot bearing plate reinforcement is evenly arranged along the upper side of the steel pipe pier on the lower side of the column foot bearing bottom plate, and the upper bearing plate reinforcement is evenly arranged along the upper side of the steel pipe pier on the upper bearing plate.

[0012] Preferably, S1 includes: adopting reasonable foundation pit support measures according to the on-site topographic and geological conditions, installing a frame structure in the foundation pit of the pedestal, the pedestal frame structure is a lattice frame, and placing the column foot annular embedded steel plate flat on the grid on the top surface of the pedestal frame structure, arranging anchor bolts penetrating the column foot annular embedded steel plate along the column foot annular embedded steel plate, and tying the bottom pressure steel bar at the bottom of the anchor bolt, and casting the lower pedestal in the pedestal frame structure.

[0013] Preferably, the grouting in S2 adopts gravity grouting, and the grouting material is injected from the center of the bottom of the steel pipe pier to the surrounding area.

[0014] The present invention provides a steel tube concrete bridge pier column foot anti-rockfall structure, comprising a layered cap structure, a column foot embedded component assembly, a column foot steel structure assembly, an outer concrete covering, and a fine-tuning positioning assembly;

[0015] The layered platform structure consists of a lower platform and an additional platform, wherein the lower platform is located below the ground, and the additional platform is located above the lower platform and exposed to the ground, for protection against falling rocks;

[0016] The column foot embedded component assembly includes a column foot annular embedded steel plate, which is embedded in the top surface of the lower pedestal, and on which anchor bolts are evenly arranged. The anchor bolts penetrate the column foot annular embedded steel plate from top to bottom and are embedded in the lower pedestal, and are tied and connected with the bottom pressure-bearing steel bars in the lower pedestal;

[0017] The column foot steel structure assembly includes a steel pipe pier, the outer periphery of the steel pipe pier is uniformly welded with shear nails, the lower part of the steel pipe pier is provided with a column foot bottom pressure bearing base plate located at the lower end and an upper pressure bearing plate near the lower end, wherein the column foot bottom pressure bearing base plate is connected to the anchor bolt; the column foot bottom pressure bearing base plate is uniformly provided with column foot pressure bearing plate reinforcement along the upper side of the steel pipe pier, and the upper pressure bearing plate reinforcement is uniformly provided along the upper side of the steel pipe pier; the said platform is cast between the column foot bottom pressure bearing base plate and the upper pressure bearing plate;

[0018] The outer concrete covers the exposed pedestal area of ​​the steel pipe pier and forms a double-layer protection system with the pedestal. The pedestal is located above the ground to protect the lower part of the pier bottom where the impact probability and impact force are greater; the outer concrete is located above the pedestal to protect the higher part of the pier top where the impact probability and impact force are less;

[0019] The fine adjustment positioning assembly is arranged between the column foot pressure base plate and the column foot annular embedded steel plate, and includes a leveling nut, a wedge block and a leveling gasket, for accurately adjusting the column foot position.

[0020] Preferably, the pressure-bearing base plate at the bottom of the column foot is provided with a hole with a diameter of 40 mm, allowing the position to be adjusted on the anchor bolt, and the adjustment amount is controlled by the gap between the hole and the anchor bolt.

[0021] Preferably, the coverage of the outer concrete is adjusted according to the probability of rockfall impact and the magnitude of the impact force, and the coverage area is from the edge of the upper bearing plate to a certain height of the steel pipe pier.

[0022] Preferably, the shear studs are welded to the surface of the steel pipe pier to enhance the bonding strength between the concrete and the steel pipe.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention sets up a layered foundation and outer concrete to reduce the volume and adapt to the lightweight characteristics of steel tube concrete structure. Compared with the traditional single anti-collision component (such as a buffer pad), it effectively reduces the volume and adapts to the light weight characteristics of steel tube concrete;

[0025] (2) At the same time, the integrated construction and fine-tuning components of the present invention reduce the difficulty and cost of installation, introduce secondary adjustments during construction, solve the common problem of insufficient precision in bridge installation, simplify the complex positioning process of indirect collision avoidance, reduce human errors, and indirectly solve the problem of high cost;

[0026] (3) The present invention is specially optimized for geological disasters in mountainous areas. The impact force of rolling stones and debris flows unique to mountainous areas is dispersed, which is more efficient than general anti-collision designs. It accurately matches the zoning protection system for the distribution of rockfall risks. At the same time, the flexible waterproof layer design completely decouples the anti-collision layer from the structural force. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the anti-rockfall structure of the steel tube concrete pier column foot of the present invention.

[0028] Figure 2 This is the elevation and plan view of the column base embedded plate of the present invention.

[0029] Figure 3 This is the elevation and plan view of the column base steel structure of the present invention.

[0030] Figure 4 This is a schematic diagram of the construction steps of the present invention.

[0031] Figure 5 This is a schematic diagram of the construction steps of the foot steel structure assembly of the present invention.

[0032] Figure 6 for Figure 4 Enlarged view of point A in the middle.

[0033] In the figure: 1. Lower bearing platform, 2. Additional platform, 3. Outer concrete, 4. Embedded component assembly of column foot, 5. Steel structure assembly of column foot, 7. Bearing platform frame, 8. Waterproof layer, 4-1. Annular embedded steel plate of column foot, 4-2. Anchor bolt, 4-3. Bottom bearing steel bar, 5-1. Bottom bearing base plate of column foot, 5-2. Reinforcement of lower bearing plate of column foot, 5-3. Steel pipe pier, 5-4. Shear nail, 5-5 Upper bearing plate, 5-6. Reinforcement of upper bearing plate, 5-7. Wedge block, 5-8. Removable steel formwork, 5-9. Thick rubber anti-leakage strip, 5-10. Bolt pad, 5-11. Nut, 5-12. Leveling nut, 5-13. Leveling gasket. DETAILED DESCRIPTION

[0034] Example 1

[0035] like Figure 1-Figure 3 As shown, the anti-rockfall structure of the steel tube concrete pier column foot of the present invention:

[0036] Layered cap structure, column base embedded component assembly, column base steel structure assembly, outsourced concrete and fine-tuning positioning assembly;

[0037] The layered cap structure consists of a lower cap 1 and an additional cap 2, wherein the lower cap 1 is located below the ground, and the additional cap 2 is located above the lower cap 1 and exposed to the ground to protect against falling rocks. The impact probability and impact force at the lower part of the pier bottom are greater, and are protected by the cap and additional cap 2. Based on the results of the on-site rockfall risk survey, the height of the additional cap 2 can be adjusted between 1.5 and 2.5 meters. The impact probability and impact force at the higher position are smaller, and are protected by the outer concrete 3. At the same time, the height of the additional cap and the height of the outer concrete 3 can be adjusted according to the on-site conditions, which makes the force transmission more solid and avoids excessive stress concentration. It is suitable for steel tube concrete pier structures with larger diameters and large loads.

[0038] The column foot embedded component assembly 4 includes a column foot annular embedded steel plate 4-1, which is embedded in the top surface of the lower pedestal 1 and evenly provided with anchor bolts 4-2. The anchor bolts 4-2 penetrate the column foot annular embedded steel plate 4-1 from top to bottom and are embedded in the lower pedestal 1, and are tied and connected with the bottom pressure steel bars 4-3 in the lower pedestal 1;

[0039] The column foot steel structure assembly 5 includes a steel pipe pier 5-3, the outer periphery of which is evenly welded with shear studs 5-4, and the lower part of the steel pipe pier 5-3 is provided with a column foot bottom pressure-bearing base plate 5-1 located at the lower end and an upper pressure-bearing plate 5-5 near the lower end, wherein the column foot bottom pressure-bearing base plate 5-1 is connected to the anchor bolt 4-2; the column foot bottom pressure-bearing base plate 5-1 is evenly provided with column foot bottom pressure-bearing plate stiffeners 5-2 along the steel pipe pier 5-3, and the upper pressure-bearing plate stiffeners 5-6 are evenly provided along the steel pipe pier 5-3 on the upper pressure-bearing plate 5-5; the said platform 2 is cast between the column foot bottom pressure-bearing base plate 5-1 and the upper pressure-bearing plate 5-5;

[0040] The outer concrete 3 covers the exposed area of ​​the steel pipe pier 5-3, and forms a double-layer protection system with the platform 2. The platform 2 is located above the ground to protect the lower part of the pier bottom where the impact probability and impact force are greater; the outer concrete 3 is located above the platform 2 to protect the higher part of the pier top where the impact probability and impact force are less;

[0041] A fine adjustment positioning assembly is provided between the column foot bearing base plate 5-1 and the column foot annular embedded steel plate 4-1, including a leveling nut 5-12, a wedge block 5-7 and a leveling gasket 5-13, for precisely adjusting the column foot position.

[0042] like Figure 4-Figure 6 As shown, the construction method of the steel tube concrete pier column foot anti-rockfall structure of the present invention includes the following steps:

[0043] S1. Positioning the embedded plate at the column foot and casting the lower cap: excavate the soil and rock around the upper end of the pier pile, set up a cap pit, install the cap frame 7 and the column foot embedded component assembly 4 in the cap pit, the column foot embedded component assembly 4 includes a column foot annular embedded steel plate 4-1, the cap frame 7 is a lattice frame, the spacing of the grid on the top surface of the cap frame 7 is smaller than the column foot annular embedded steel plate 4-1, the column foot annular embedded steel plate 4-1 is horizontally positioned on the top surface grid of the cap frame 7 by steel pipe brackets 4-4, embedded anchor bolts 4-2 are evenly arranged along the circumference of the column foot annular embedded steel plate 4-1 and vertically penetrate the column foot annular embedded steel plate 4-1, the lower side of the anchor bolts 4-2 is tied and connected to the bottom pressure steel bar 4-3, and finally cast the lower cap 1;

[0044] S2. Hoisting and fine-tuning of column foot steel structure: hoist column foot steel structure assembly 5, and preliminarily locate it through the opening of column foot pressure base plate 5-1 and anchor bolt 4-2. Since the opening size of column foot pressure base plate 5-1 is 40mm, there is a certain amount of adjustment. Therefore, the pier body adopts leveling nuts and wedges to adjust the elevation and horizontality, including: wedge-shaped blocks 5-7 are wedged between column foot pressure base plate 5-1 and column foot annular embedded steel plate 4-1 to perform a second precise horizontal positioning adjustment on column foot pressure base plate 5-1; then use leveling nuts 5-12 provided on the outer surface of anchor bolt 4-2 to fix the distance between column foot pressure base plate 5-1 and column foot annular embedded steel plate 4-1. When adjusting the horizontal position of the pier body within the adjustment range of the bolt hole, use

[0045] Use wedge blocks 5-7 to assist in adjustment. Finally, roughen the surface of the pier base at the bottom of the pier to remove debris. Install a detachable steel formwork 5-8 around the upper surface of the lower pier base 1 on the outer periphery of the column base annular pre-embedded steel plate 4-1. Wet the pier base surface with water and secure a circle of rubber anti-leakage strips 5-9 to the top of the lower pier base on the outer bottom of the detachable steel formwork 5-8 using expansion bolts. Next, grout the steel pipe pier 5-3 from the center of the pier base to the surrounding areas until the grouting material is flush with the top of the column base pressure base plate 5-1. After the grouting material reaches the designed strength, remove the steel formwork 5-8 and check for leaks. If necessary, fill the leaks. Finally, install bolt pads 5-10 and nuts 5-11 outside the anchor bolts 4-2 exposed on the upper surface of the column base pressure base plate 5-1. Tighten them initially, weld the pads around them, and pour the grouting layer. The direct tensioning method is used to pre-tighten the bolts.

[0046] S3, pouring concrete in the platform and steel pipe: tie the reinforcement of platform 2 and the PBL reinforcement of column base outside the column base steel structure component 5, pour the concrete of platform 2 and the concrete in the steel pipe pier 5-3, and pour the concrete in the steel pipe by throwing from the top of the pipe;

[0047] S4. Outer concrete construction: tie the outer concrete 3 steel bars, set a waterproof layer on the edge of the upper bearing plate 5-5, and pour the outer concrete 3.

[0048] In addition, a 10cm area around the edge of the upper bearing plate 5-5 was cut at a 1:10 slope and laid with a 3mm MMA waterproofing layer 8. Steel tube outer concrete was poured above the waterproofing layer 8 to ensure that rainwater can drain along the steel plate and avoid water accumulation. The addition of an MMA waterproofing layer prevents the outer concrete from participating in the overall load-bearing of the steel tube concrete pier, which could prevent cracking caused by bending moment at the pier base.

[0049] The description of the direction and relative position relationship of the structure in the present invention, such as the description of front, back, left, right, up and down, does not constitute a limitation of the present invention and is only for the convenience of description.

Claims

1. A construction method for a concrete-filled steel tube bridge pier column foot anti-rockfall structure, characterized in that: The following steps are involved: S1, pouring the lower pedestal (1), forming a horizontal column foot embedded plate (4-1) on the upper surface of the lower pedestal (1), exposing a plurality of anchor bolts (4-2) on the upper side of the column foot embedded plate (4-1), and the anchor bolts (4-2) are evenly distributed; S2. Hoisting and fine-tuning of the column foot steel structure: Install a leveling nut (5-12) on the side of each anchor bolt (4-2) exposed from the column foot annular pre-buried steel plate (4-1), then place a leveling washer (5-13) on the leveling nut (5-12), hoist the column foot steel structure assembly (5), make the opening of the evenly opened column foot pressure-bearing base plate (5-1) and the anchor bolt (4-2) preliminarily aligned, and seat it on the leveling washer (5-13), use a wedge block (5-7) to insert between the column foot pressure-bearing base plate (5-1) and the column foot annular pre-buried steel plate (4-1) to adjust the column foot pressure-bearing base plate (5-1), adjust the elevation of the leveling nut (5-12) until the leveling gasket (5-13) is close to the column foot pressure base plate (5-1), install a detachable steel mold (5-8) surrounding the column foot annular pre-buried steel plate (4-1) on the upper surface of the lower pedestal (1) and set a rubber anti-leakage strip (5-9), use gravity grouting to cast the area between the column foot pressure base plate (5-1) and the column foot annular pre-buried steel plate (4-1), install fasteners outside the anchor bolts (4-2) exposed on the upper surface of the column foot pressure base plate (5-1), and tighten the column foot pressure base plate (5-1); S3, pouring concrete for the additional platform and steel pipe: tying the additional platform (2) steel bars outside the column foot steel structure assembly (5), pouring concrete for the additional platform (2) and concrete inside the steel pipe pier (5-3); S4, external concrete construction: tie the external concrete (3) steel bars, set a waterproof layer (8) on the edge of the upper bearing plate (5-5), and pour the external concrete (3) on the steel pipe pier (5-3) above the waterproof layer (8); The column foot steel structure assembly (5) comprises a steel pipe pier (5-3), the outer periphery of which is uniformly welded with shear studs (5-4), and the lower portion of the steel pipe pier (5-3) is provided with a column foot bottom pressure-bearing base plate (5-1) located at the lower end and an upper pressure-bearing plate (5-5) close to the lower end, wherein the opening diameter of the column foot bottom pressure-bearing base plate (5-1) is larger than the anchor bolt (4-2).

2. The construction method of the concrete-filled steel tube bridge pier column foot rockfall prevention structure according to claim 1, characterized in that: The column foot bearing plate reinforcement (5-2) is evenly arranged on the upper side of the column foot bearing bottom plate (5-1) along the steel pipe pier (5-3), and the upper bearing plate reinforcement (5-6) is evenly arranged on the upper side of the upper bearing plate (5-5) along the steel pipe pier (5-3).

3. The construction method of the steel tube concrete pier column foot anti-rockfall structure according to claim 1, characterized in that: S1 includes: According to the on-site topographic and geological conditions, reasonable foundation pit support measures are adopted, and a foundation foundation frame (7) is installed in the foundation foundation pit. The foundation foundation frame (7) is a steel lattice steel frame. The column foot annular pre-embedded steel plate (4-1) is placed flat on the grid of the top surface of the foundation foundation frame (7). Anchor bolts (4-2) that penetrate the column foot annular pre-embedded steel plate (4-1) are arranged in an annular manner along the column foot annular pre-embedded steel plate (4-1), and bottom pressure-bearing steel bars (4-3) are tied to the bottom of the anchor bolts (4-2). The lower foundation foundation (1) is cast in the foundation foundation frame (7).

4. The construction method of the concrete-filled steel tube bridge pier column foot anti-rockfall structure according to claim 1, characterized in that: The grouting in S2 adopts the gravity grouting method, and the grouting material is injected from the center of the bottom of the steel pipe pier (5-3) to the surrounding areas.

5. A steel tube concrete pier column foot rockfall prevention structure installed using the construction method according to any one of claims 1 to 4, characterized in that: It includes layered foundation structure, column base embedded component assembly, column base steel structure assembly, outsourcing concrete and fine-tuning positioning assembly; The layered support structure consists of a lower support (1) and an additional platform (2), wherein the lower support (1) is located below the ground, and the additional platform (2) is located above the lower support (1) and exposed to the ground, for protecting against falling rocks; The column foot embedded component assembly (4) comprises a column foot annular embedded steel plate (4-1), which is embedded in the top surface of the lower pedestal (1) and evenly provided with anchor bolts (4-2). The anchor bolts (4-2) penetrate the column foot annular embedded steel plate (4-1) from top to bottom and are embedded in the lower pedestal (1), and are tied and connected with the bottom pressure-bearing steel bars (4-3) in the lower pedestal (1); The column foot steel structure assembly (5) comprises a steel pipe pier (5-3), the outer periphery of which is uniformly welded with shear studs (5-4), the lower portion of the steel pipe pier (5-3) is provided with a column foot bottom pressure-bearing base plate (5-1) located at the lower end and an upper pressure-bearing plate (5-5) close to the lower end, wherein the column foot bottom pressure-bearing base plate (5-1) is connected to the anchor bolt (4-2); the upper side of the column foot bottom pressure-bearing base plate (5-1) is uniformly provided with column foot bottom pressure-bearing plate reinforcements (5-2) along the steel pipe pier (5-3), and the upper side of the upper pressure-bearing plate (5-5) is uniformly provided with upper pressure-bearing plate reinforcements (5-6) along the steel pipe pier (5-3); the added platform (2) is cast between the column foot bottom pressure-bearing base plate (5-1) and the upper pressure-bearing plate (5-5); The outer casing concrete (3) covers the exposed platform (2) area of ​​the steel pipe pier (5-3); The fine adjustment positioning assembly is arranged between the column foot pressure base plate (5-1) and the column foot annular embedded steel plate (4-1), and includes a leveling nut (5-12), a wedge block (5-7) and a leveling washer (5-13), and is used for accurately adjusting the column foot position.

6. The rockfall prevention structure for concrete-filled steel tube bridge pier foot according to claim 4, characterized in that: The column foot bottom pressure bearing bottom plate (5-1) is provided with a hole with a diameter of 40 mm, which allows the position to be adjusted on the anchor bolt, and the adjustment amount is controlled by the gap between the hole and the anchor bolt.

7. The rockfall prevention structure for concrete-filled steel tube bridge pier foot according to claim 4, characterized in that: The coverage of the outer concrete (3) is adjusted according to the probability of rockfall impact and the magnitude of the impact force, and the coverage area is from the edge of the upper bearing plate (5-5) to the steel pipe pier (5-3).

8. The rockfall prevention structure for concrete-filled steel tube bridge pier column foot according to claim 4, characterized in that: The shear nails (5-4) are welded to the surface of the steel pipe pier (5-3) and are used to enhance the bonding strength between the concrete and the steel pipe.

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