A heavy-load anti-tension safety device and method for bridge construction under constrained conditions

Abstract

This invention discloses a heavy-load anti-tension safety device and method for bridge construction under constrained conditions, belonging to the field of bridge construction technology. It includes a pier cap and pile foundations. The pier cap has a main support tower on top, and the pile foundation has a heavy-load assembly support on top. This invention, through a flexible joint treatment method using flexible slings encircling the pile foundation, exhibits good adaptability and operability in situations with high water levels and constrained construction environments. Furthermore, the use of a six-stage tensioning process actively controls the tension force, replacing direct steel strand connection or rigid connection methods. This avoids the adverse effects of excessive tension on the structure, making the device suitable for the construction of large-scale projects such as long-span steel truss bridges. It can adapt to various complex environments and construction conditions, optimizing the connection node design, tensioning timing, and number of tensioning operations, thus improving construction efficiency and safety.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a heavy-load anti-tension safety device and method for bridge construction under limited conditions. Background Technology

[0002] With the continuous advancement of infrastructure construction, large-scale projects such as long-span steel truss bridges are gradually increasing. In these projects, the connection between long-distance heavy-load structures has become a key link in construction. During the construction of auxiliary supports, due to the relatively soft and poor soil quality of the riverbank and the low lateral resistance, there may be slope slippage, settlement and cracking of the bank line, resulting in gaps in the bank line. If the slippage on the bank line continues to expand, it may cause the auxiliary supports to shift. If the supports continue to deform, it will bring safety hazards to the steel beam jacking operation. Therefore, it is necessary to limit the shift of the auxiliary supports and implement safety insurance measures.

[0003] In the construction of long-distance, heavy-load structures, traditional technical solutions are mainly designed for construction conditions where the structures are close together and bear relatively small loads. However, with the continuous advancement of infrastructure construction, the demand for large-scale projects such as long-span steel truss bridges is constantly increasing. These projects often face complex environments such as long distances, heavy loads, and adverse geological and hydrological conditions. This results in poor adaptability and construction convenience when dealing with the connection between long-distance, heavy-load structures under adverse geological and hydrological conditions, leading to low construction safety and efficiency. Traditional technologies can no longer meet the needs of these projects. Therefore, we propose a heavy-load anti-tension safety device and method for bridge construction under limited conditions to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to address the increasing demand for large-scale engineering projects, such as long-span steel truss bridges, which face complex environments such as long distances, heavy loads, and adverse geological and hydrological conditions. Due to the long distances between structures and the limited available space, traditional rigid connection methods are difficult to implement. At the same time, the loads they bear are large, resulting in poor adaptability and construction convenience. Therefore, this invention proposes a heavy-load anti-tension safety device and method for bridge construction under limited conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a heavy-load anti-tension safety device for bridge construction under limited conditions, comprising a pier cap and pile foundation, wherein the top of the pier cap is provided with a load-bearing main tower; The top of the pile foundation is equipped with a heavy-duty assembly support. The main support tower away from the heavy-duty assembly support is equipped with two anti-tension distribution beams. Flexible slings are fitted on multiple pile foundations in the middle. Four steel strands are installed on the two anti-tension distribution beams. The other end of the steel strands is connected to the flexible slings. A steel anchor box is installed between the flexible slings and the steel strands. A bearing support is installed between the anti-tension distribution beam and the pile cap, and limit baffles are installed at the corresponding positions of the pile foundation and the flexible sling.

[0006] Preferably, a temporary trestle is provided between the main support tower and the pile foundation. The temporary trestle is located directly below the steel strand, and a tensile tension testing point is provided near the connection point between the temporary trestle and the steel strand.

[0007] Preferably, a reaction seat is provided on the side of the anti-tension distribution beam away from the main support tower. One end of the steel strand passes through the anti-tension distribution beam and the reaction seat and is connected to a support anchor system. The support anchor system consists of an anchor plate and an anchor support plate. The number of bundles of the steel strand is equal to the number of reaction seats.

[0008] Preferably, the anti-tension distribution beam is provided with a diagonal brace on the side near the main support tower, and the diagonal brace and the anti-tension distribution beam are provided with pads on the side near the main support tower.

[0009] Preferably, the number of flexible slings, steel strands, and steel anchor boxes are equal, and the flexible slings can be connected to the steel strands by the steel anchor boxes.

[0010] Preferably, the limiting baffle is assembled on the top of the pile foundation, the bottom of the limiting baffle is inclined, the bottom of the limiting baffle matches the inclination angle of the flexible sling, and the side of the limiting baffle is provided with arc-shaped protective measures.

[0011] Preferably, a steel casing is provided on the outside of the pile foundation, the limiting baffle is sleeved on the outside of the steel casing, and the flexible sling is sleeved on the outside of the steel casing.

[0012] Preferably, the flexible sling adopts R02-25 protective type, the length of the flexible sling at the edge is 14000mm, the length of the flexible sling in the middle is 12500mm, and the angle of the flexible sling corresponds to and matches the adjacent steel strand.

[0013] A construction method for a heavy-load anti-tension safety device in bridge construction under constrained conditions. Step 1: Conduct localized cleaning around the pile foundation of the heavy-duty assembly support, and weld limiting baffles at specific positions on the steel casing to limit the flexible slings; the upper part of the limiting baffles is welded and fixed to the steel casing by vertical stiffening plates, and the ends of the limiting baffles are protected by arc-shaped protection measures and rounded transition treatment to prevent cutting the flexible slings; Step 2: Wrap the flexible sling around the bottom of the limiting baffle and temporarily suspend and fix it. At the same time, place the steel anchor box at the designed position of the pile head. The ring joints at both ends of the flexible sling are connected to the steel anchor box through pins. Step 3: Based on the foundation, pour concrete strip foundations as the foundation for the load-bearing support. After the load-bearing support is assembled on the ground, it is hoisted as a whole and fixed by welding through the embedded parts of the strip foundation after layout and verification. Step 4: Hoist the anti-tension distribution beam and place it above the bearing support, close to the bearing main tower. Weld steel pipe diagonal braces on the anti-tension distribution beam and close to the bearing main tower to resist the horizontal component force generated by tension. To protect the concrete surface of the main tower, rubber pads are used between the anti-tension distribution beam and the diagonal braces and the bearing main tower. Step 5: After the steel strands are cut to size, install them one by one. One end is anchored to the steel anchor box on the side of the pile foundation, and the other end passes through the duct of the anti-tension distribution beam and is anchored to the reaction seat of the distribution beam. The reaction seat is welded to the back of the anti-tension distribution beam, and the steel strands pass through the pre-reserved duct in the beam and emerge from the reaction seat. Step Six: The steel strands on both sides of the main tower are tensioned simultaneously. For the initial tensioning, each bundle of steel strands is considered to have a tension of 50t (only the steel strands are tensioned). After tensioning is completed, the steel strands are anchored at the reaction seat. Subsequently, the heavy-duty assembly support is continuously monitored, and additional tensioning is considered based on its continued displacement and deformation. Step 7: Install a cable force gauge on the steel strand for cable force monitoring. This will be used in conjunction with daily displacement and deformation monitoring to assess the structural safety status and determine the timing for subsequent additional tensioning. If the daily displacement of the cable force gauge exceeds 2mm, a warning value is reached, requiring enhanced monitoring and data verification. If the displacement exceeds 2mm for several consecutive days, an alarm value is reached. It is necessary to check whether the instrument is malfunctioning and verify whether there are any errors in data acquisition, and take the next steps according to the handling plan.

[0014] Compared with the prior art, the present invention provides a heavy-load anti-tension safety device and method for bridge construction under constrained conditions, which has the following beneficial effects: (1) The present invention adopts a flexible joint treatment method of flexible sling wrapping around the pile foundation at the anchoring end, which has good adaptability and operability in the case of high water level and limited construction environment; the steel anchor box and flexible sling are all manufactured in the factory, which greatly reduces the difficulty of on-site construction and shortens the construction cycle; at the same time, the flexible joint design has spatial angle adjustment, which can improve the tolerance of on-site construction.

[0015] (2) The present invention adopts the treatment method of anti-tension distribution beam node at the tension end. The anti-tension distribution beam and the main tower are balanced by adaptive diagonal bracing to balance the horizontal load generated by the tension force. The vertical structure adopts prefabricated support frame. The structure has the advantages of clear force and convenient construction. While protecting the main tower structure, the materials have good turnover and economy, saving construction costs.

[0016] (3) In the use stage, the present invention adopts a six-level tensioning method to actively control the tension force, replacing the fixing method of direct tie or rigid connection of steel strands; the initial tensioning only tightens the steel strands as a safety measure to avoid the adverse effects of excessive tension on the structure at one time. If the structure continues to displace, the tension force is gradually increased. At the same time, a warning value of tension force is set. The relative displacement of the structure is controlled, which has higher safety and is suitable for the counter-tension adjustment in narrow water temperature environments.

[0017] (4) The steel strand and bearing anchor system of the present invention consists of anchor plate and anchor support plate, controlled by jack, and can be extended and adjusted to adjust tension load and tension times, and determine the optimal tensioning time according to the pile foundation deformation. It is adaptable and convenient to construction, making the device suitable for the construction of large-scale projects such as large-span steel truss bridges. It can adapt to various complex environments and construction conditions, and has a good ability to adjust and adapt to the phenomenon of continuous sliding of water level slope soil. It optimizes the design of connection nodes, tensioning time, tension load and number of times, improves construction efficiency and safety factor, and reduces construction cost and construction time.

[0018] (5) By connecting the heavy-duty assembly support to the rear supporting main tower with a counter-tension connection, the invention restricts the continued displacement and deformation of the heavy-duty assembly support. The counter-tension measure can play a safety role in the construction process and prevent the occurrence of safety risks under the most unfavorable working conditions. Attached Figure Description

[0019] Figure 1 This is a front view schematic diagram of the structure of the present invention; Figure 2 This is a top view of the structure of the present invention; Figure 3 This is a top view schematic diagram of the connection structure between the anti-tension distribution beam and the diagonal brace of the present invention; Figure 4 This is a front view schematic diagram of the connection structure between the steel strand and the steel anchor box of the present invention; Figure 5 This is a top view schematic diagram of the connection structure between the flexible sling and the steel anchor box of the present invention; Figure 6 This is a side view of the connection structure between the foundation and the main tower of the present invention; Figure 7 This is a front view schematic diagram of the connection structure between the steel strand and the load-bearing anchor system of the present invention; Figure 8 This is a top view schematic diagram of the connection structure between the steel strand and the steel anchor box of the present invention; Figure 9 This is a front view schematic diagram of the connection structure between the steel strand and the steel anchor box of the present invention; Figure 10 This is a front view schematic diagram of the connection structure between the anti-tension distribution beam and the load-bearing support of the present invention; Figure 11 This is a side view schematic diagram of the connection structure between the anti-tension distribution beam and the load-bearing support of the present invention; Figure 12 This is a schematic diagram of the flexible sling connection structure of the present invention.

[0020] In the diagram: 1. Foundation; 2. Pile foundation; 3. Main load-bearing tower; 4. Heavy-duty assembly support; 5. Counter-tension distribution beam; 6. Flexible sling; 7. Steel strand; 8. Steel anchor box; 9. Load-bearing support; 10. Limiting baffle; 11. Reaction seat; 12. Load-bearing anchor system; 13. Diagonal brace; 14. Pad; 15. Steel casing; 16. Temporary trestle. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship 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 limitations on this invention.

[0023] Reference Figure 1-12 A heavy-load anti-tension safety device for bridge construction under limited conditions includes a pier cap 1 and a pile foundation 2, with a load-bearing main tower 3 provided on the top of the pier cap 1. The top of the pile foundation 2 is equipped with a heavy-duty assembly support 4. The main tower 3 is equipped with two anti-tension distribution beams 5 on the side away from the heavy-duty assembly support 4. Flexible slings 6 are fitted on multiple pile foundations 2 in the middle. Four steel strands 7 are installed on the two anti-tension distribution beams 5. The other end of the steel strands 7 is connected to the flexible slings 6. A steel anchor box 8 is installed between the flexible slings 6 and the steel strands 7. A load-bearing bracket 9 is installed between the anti-tension distribution beam 5 and the pile cap 1, and limit baffles 10 are installed at the corresponding positions of the pile foundation 2 and the flexible sling 6. The beneficial effects of this scheme are as follows: A steel strand 7 is installed between the main support tower 3 and the heavy-duty assembly support 4. A flexible sling 6 is fitted onto the pile foundation 2 and connected to the steel strand 7 by a steel anchor box 8. A limiting baffle 10 limits the flexible sling 6, effectively resisting the effects of water flow scouring and slippage. The other end of the steel strand 7 is fixed to the anti-tension distribution beam 5. The steel strand 7 provides anti-tension load between the pile foundation 2 and the main support tower 3. The steel strand 7 is connected to the main support tower 3 through a reaction seat 11 and a support anchor system 12. The support anchor system 12 consists of anchor plates and anchor support plates. The system, controlled by jacks, allows for fine-tuning of the tensioning load and number of tensioning cycles, determining the optimal tensioning timing based on the deformation of pile foundation 2. This ensures structural safety while minimizing the impact on the main tower structure, resulting in a flexible overall connection for the heavy-load anti-tensioning system. This makes the system adaptable and convenient for construction, suitable for large-scale projects such as long-span steel truss bridges. It can adapt to various complex environments and construction conditions, optimizing the connection node design, tensioning timing, load, and number of tensioning cycles, thus improving construction efficiency and safety while reducing construction costs and time.

[0024] Each pile foundation 2 is surrounded by 2 slings. An alternative is to surround each pile foundation 2 with 1 sling or more slings, depending on the tension and the material of the slings.

[0025] One option in this application is that the initial tension of each bundle of steel strands 7 is 50t. An alternative option is that the tension of each bundle of steel strands 7 is 70t, or greater or less, which can be adjusted appropriately according to the actual tension of the steel strands 7.

[0026] In this embodiment, a temporary trestle 16 is further provided between the main tower 3 and the pile foundation 2. The temporary trestle 16 is located directly below the steel strand 7, and a tensile tension detection point is provided near the connection point between the temporary trestle 16 and the steel strand 7. By setting up a temporary trestle bridge 16 between the main tower 3 and the pile foundation 2, the load counter-tension of the steel strand 7 can be detected. Construction personnel can be positioned at the temporary trestle bridge 16 to detect the counter-tension load of the steel strand 7 from the tensile tension detection point, making the detection convenient.

[0027] In this embodiment, further, a reaction seat 11 is provided on the side of the anti-tension distribution beam 5 away from the main support tower 3. One end of the steel strand 7 passes through the anti-tension distribution beam 5 and the reaction seat 11 and is connected to the support anchor system 12. The support anchor system 12 is composed of an anchor plate and an anchor support plate. The number of bundles of steel strand 7 is equal to the number of reaction seats 11. By setting reaction seats 11, which are equal in number and matched in angle and position with the steel strands 7, they can be adapted to the tensile tilt angle of the steel strands 7, resulting in excellent load-bearing capacity. The load-bearing anchor system 12 consists of anchor plates and anchor support plates, controlled by jacks, and can be extended and adjusted to adjust the tension load and tensioning times, thus determining the optimal tensioning time. Based on the deformation of the pile foundation 2, the impact on the main tower structure is minimized while ensuring structural safety. This makes the overall construction heavy-load counter-tension system a flexible connection, which is more adaptable and convenient for construction, and solves the problem of unbalanced horizontal force components.

[0028] In this embodiment, further, the anti-tension distribution beam 5 is provided with a diagonal brace 13 on the side near the main support tower 3, and the diagonal brace 13 and the anti-tension distribution beam 5 are provided with a pad 14 on the side near the main support tower 3. The diagonal brace 13 and the main tower 3 bear each other under pressure, providing pressure support for the anti-tension distribution beam 5. The support pad 14 is supported between the anti-tension distribution beam 5, the main tower 3, and the diagonal brace 13. A 100mm rubber pad + 40mm steel plate support pad 14 is used between the anti-tension distribution beam 5 and the main tower 3. The diagonal brace 13 is installed on the anti-tension distribution beam 5 and connected to the main tower to withstand the tension horizontal force. A 50mm MGB plate + 20mm steel plate support pad 14 is used between the diagonal brace 13 and the main tower. A limiting bracket is welded below the rubber pad for limiting movement.

[0029] In this embodiment, the number of flexible slings 6, steel strands 7, and steel anchor boxes 8 are equal, and the flexible slings 6 can be connected to the steel strands 7 by the steel anchor boxes 8; The number of flexible slings 6, steel strands 7, and steel anchor boxes 8 are equal. According to the corresponding requirements, the steel strands 7 are at a spatial angle and need to be anchored on the side of the main tower to provide the space for tensioning.

[0030] In this embodiment, the limiting baffle 10 is further assembled on the top of the pile foundation 2, the bottom of the limiting baffle 10 is inclined, the bottom of the limiting baffle 10 matches the inclination angle of the flexible sling 6, and the side of the limiting baffle 10 is provided with arc-shaped protective measures. The arc-shaped protection measure ensures that the limiting measure will not cut or damage the steel strand 7, and ensures that the force on the steel strand 7 is clear; By setting a limiting baffle 10 and installing it on the pile foundation 2, the flexible sling 6 is limited, effectively resisting the effects of water flow scouring and slippage. The arc-shaped protection measure can be arc-shaped and can be adapted to limit the flexible sling 6, so that the flexible sling 6 can play a better limiting role when it is in flexible displacement.

[0031] In this embodiment, a steel casing 15 is further provided on the outside of the pile foundation 2, a limiting baffle 10 is sleeved on the outside of the steel casing 15, and a flexible sling 6 is sleeved on the outside of the steel casing 15. The flexible sling 6 is wrapped around the steel casing 15, and the flexible sling 6 is connected to the steel anchor box 8 by a pin. Two flexible slings 6 are set for each pile foundation 2. In combination with the construction needs, the sling is made of polyester material. Under the conditions of flowing water, non-stagnant water, relatively low water pollution, and temperature not exceeding 70°, the long-term operation in the underwater environment has little impact on its function. It has the characteristics of being soft, lightweight, and having a large load capacity, which can meet the construction needs.

[0032] In this embodiment, the flexible sling 6 is further of R02-25 protective type, the length of the flexible sling 6 at the edge is 14000mm, the length of the flexible sling 6 in the middle is 12500mm, and the angle of the flexible sling 6 corresponds to and matches the adjacent steel strand 7. The flexible sling 6 adopts the R02-25 protective type. According to the performance parameters of the flexible sling 6, the safety reserve of the 250t sling itself is 6 times, and a single sling can withstand a tensile force of 250t.

[0033] A construction method for a heavy-load anti-tension safety device for bridge construction under limited conditions, aiming to improve construction convenience. Step 1: Clean up the area around the pile foundation 2 of the heavy-duty assembly support 4. Weld a limiting baffle 10 at a specific position on the steel casing 15 to limit the flexible sling 6. The limiting baffle 10 is fixed to the steel casing 15 by welding a vertical stiffening plate above it. The end of the limiting baffle 10 is protected by an arc shape and a rounded transition is adopted to prevent the flexible sling 6 from being cut. Step 2: Wrap the flexible sling 6 around the bottom of the limiting baffle 10 for temporary suspension and fixation. At the same time, place the steel anchor box 8 at the designed position of the pile head. The annular joints at both ends of the flexible sling 6 are connected to the steel anchor box 8 through pins. Step 3: Based on the foundation 1, pour concrete strip foundation as the foundation for the load-bearing support 9. After the load-bearing support 9 is assembled on the ground, it is hoisted as a whole and fixed by welding through the embedded parts of the strip foundation after layout and verification. Step 4: Hoist the anti-tension distribution beam 5 above the bearing support 9 and place it in close contact with the bearing main tower 3. Weld steel pipe diagonal braces 13 onto the anti-tension distribution beam 5 and place them in close contact with the bearing main tower 3 to resist the horizontal component force generated by tension. To protect the concrete surface of the main tower, rubber pads 14 are used between the anti-tension distribution beam 5 and the diagonal braces 13 and the bearing main tower 3. Step 5: After the steel strands 7 are cut, install them one by one. One end is anchored to the steel anchor box 8 on the side of the pile foundation 2, and the other end passes through the beam body duct of the anti-tension distribution beam 5 and is anchored to the reaction seat 11 of the distribution beam. The reaction seat 11 is welded to the back of the anti-tension distribution beam 5, and the steel strands 7 pass through the pre-reserved duct in the beam and emerge from the reaction seat 11. Step 6: The steel strands 7 on both sides of the main tower are tensioned simultaneously. For the initial tensioning, each bundle of steel strands 7 is considered to have a tension of 50t (only the steel strands 7 are tensioned). After tensioning is completed, the steel strands 7 are anchored at the reaction seat 11. Subsequently, the heavy-duty assembly support 4 is continuously monitored, and additional tensioning is considered based on its continued displacement and deformation. Step 7: Install a cable force gauge on the steel strand 7 for cable force monitoring. This will be used in conjunction with daily displacement and deformation monitoring to assess the structural safety status and the timing of subsequent additional tensioning. If the daily displacement of the cable force gauge exceeds 2mm, a warning value is reached, requiring enhanced monitoring and data verification. If the displacement exceeds 2mm for several consecutive days, an alarm value is reached. It is necessary to check whether the instrument is malfunctioning and verify whether there are any errors in data acquisition, and take the next steps according to the handling plan.

[0034] This patent proposal adopts a graded tensioning control method; through multi-stage tensioning, dynamic adjustments can be made according to the displacement of the heavy-load structure and the changes in cable force; this tensioning control method simplifies the construction process, improves construction efficiency and safety factor, and reduces the impact on the main tower structure.

[0035] The working principle of this invention is as follows: By pre-casting the foundation 1 deep in the soil, the main tower 3 is set on the foundation 1 to provide stable support. The pile foundation 2 is cast near the river channel and provides fixed support for the heavy-duty assembly support 4 at the top. The foundation 1 is equipped with a support support 9, which, together with the support of the main tower 3, allows the anti-tension distribution beam 5 to be stably assembled and installed. A flexible sling 6 is sleeved on the pile foundation 2 and connected to the steel strand 7 by the steel anchor box 8. The other end of the steel strand 7 is fixed to the anti-tension distribution beam 5. The limiting baffle 10 is installed on the pile foundation 2 to limit the flexible sling 6 and effectively resist the effects of water flow scouring and slippage. A steel strand 7 provides counter-tension load between the pile foundation 2 and the main support tower 3 to prevent ground displacement caused by soil erosion when the pile foundation 2 is poured on unfavorable geological conditions, thus affecting the stability of the pile foundation 2. The steel strand 7 is connected to the pile foundation 2 via a flexible sling 6 and a steel anchor box 8. The steel strand 7 is connected to the main support tower 3 via a reaction seat 11 and a support anchor system 12. The reaction seat 11 is inclined to provide load capacity. The support anchor system 12 consists of anchor plates and anchor support plates, controlled by jacks, allowing for fine-tuning to adjust the tension load and tensioning cycles. The optimal tensioning timing was determined based on the deformation of pile foundation 2. Under the premise of ensuring structural safety, the impact on the main tower structure was minimized. Load counter-tensioning can be carried out in a confined space, so that the overall construction heavy-load counter-tensioning is a flexible connection. The adaptability and construction convenience make the device suitable for the construction of large-scale projects such as large-span steel truss bridges. It can adapt to various complex environments and construction conditions. The design of connection nodes, tensioning timing, tensioning load and number of times were optimized, which improved construction efficiency and safety factor, and reduced construction cost and construction time.

[0036] In the context of construction environments with adverse geological and hydrological conditions, this patent proposal employs a special node design and tension control method. For example, for construction conditions in water-related environments, a design of flexible slings 6 encircling joints and limiting baffles 10 is adopted to effectively resist the effects of water flow scouring and slippage. This node design can adapt to various complex environmental factors, improving the adaptability and safety of construction. Considering that the main support tower 3 is a concrete A-shaped tower with multiple spatial angles, attention should be paid to the protection of the main tower. Also, the anti-tension steel strand 7 is at a spatial angle, so it needs to be anchored on the side of the main tower and provided with tensioning space. By connecting the heavy-duty assembly support 4 to the rear supporting main tower 3 with a counter-tension connection, the displacement and deformation of the heavy-duty assembly support 4 are restricted, thereby improving the stability and reliability of the construction process. This counter-tension device design can adapt to long-distance, heavy-load construction conditions and provides an effective solution.

[0037] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A heavy-load anti-tension safety device for bridge construction under constrained conditions, comprising a pier cap (1) and a pile foundation (2), characterized in that: The top of the pier (1) is provided with a main tower (3). The top of the pile foundation (2) is provided with a heavy-duty assembly support (4). The main support tower (3) is provided with two anti-tension distribution beams (5) on the side away from the heavy-duty assembly support (4). Flexible slings (6) are fitted on multiple pile foundations (2) in the middle. Four bundles of steel strands (7) are assembled on the two anti-tension distribution beams (5). The other end of the steel strands (7) is connected to the flexible slings (6). A steel anchor box (8) is installed between the flexible slings (6) and the steel strands (7) for conversion. A bearing support (9) is installed between the anti-tension distribution beam (5) and the pile cap (1), and a limit baffle (10) is installed at the corresponding position of the pile foundation (2) and the flexible sling (6). The anti-tension distribution beam (5) is provided with a reaction seat (11) on the side away from the main support tower (3). One end of the steel strand (7) passes through the anti-tension distribution beam (5) and the reaction seat (11) and is connected to the support anchor system (12). The support anchor system (12) is composed of an anchor plate and an anchor support plate. The number of bundles of the steel strand (7) is equal to the number of reaction seats (11). The anti-tension distribution beam (5) is provided with a diagonal brace (13) on the side near the main support tower (3), and the diagonal brace (13) and the anti-tension distribution beam (5) are provided with a pad (14) on the side near the main support tower (3).

2. The heavy-load anti-tension safety device for bridge construction under confined conditions according to claim 1, characterized in that, A temporary trestle (16) is provided between the main tower (3) and the pile foundation (2). The temporary trestle (16) is located directly below the steel strand (7). A tensile tension detection point is provided near the connection point between the temporary trestle (16) and the steel strand (7).

3. The heavy-load anti-tension safety device for bridge construction under confined conditions according to claim 1, characterized in that, The number of the flexible sling (6), steel strand (7) and steel anchor box (8) are equal, and the flexible sling (6) is connected to the steel strand (7) by the steel anchor box (8).

4. The heavy-load anti-tension safety device for bridge construction under confined conditions according to claim 1, characterized in that, The limiting baffle (10) is mounted on the top of the pile foundation (2). The bottom of the limiting baffle (10) is inclined. The bottom of the limiting baffle (10) matches the inclination angle of the flexible sling (6). The side of the limiting baffle (10) is provided with arc-shaped protection measures.

5. A heavy-load anti-tension safety device for bridge construction under confined conditions according to claim 1, characterized in that, The outer side of the pile foundation (2) is provided with a steel casing (15), the limiting baffle (10) is sleeved on the outer side of the steel casing (15), and the flexible sling (6) is sleeved on the outer side of the steel casing (15).

6. A heavy-load anti-tension safety device for bridge construction under confined conditions according to claim 1, characterized in that, The flexible sling (6) adopts R02-25 protective type. The length of the flexible sling (6) at the edge is 14000mm, and the length of the flexible sling (6) in the middle is 12500mm. The angle of the flexible sling (6) corresponds to and matches the adjacent steel strand (7).

7. A construction method for a heavy-load anti-tension safety device for bridge construction under confined conditions, as described in any one of claims 1 to 6, characterized in that: Step 1: Clean up the area around the pile foundation (2) of the heavy-duty assembly support (4), and weld a limiting baffle (10) at a specific position on the steel casing (15) to limit the flexible sling (6); the limiting baffle (10) is fixed to the steel casing (15) by welding vertical stiffeners above it, and the end of the limiting baffle (10) is provided with arc-shaped protection measures and rounded transition treatment to prevent the flexible sling (6) from being cut. Step 2: Wrap the flexible sling (6) around the bottom of the limiting baffle (10) and temporarily suspend and fix it. At the same time, place the steel anchor box (8) at the designed position of the pile head. The ring joints at both ends of the flexible sling (6) are connected to the steel anchor box (8) through pins. Step 3: Based on the foundation (1), pour concrete strip foundation as the foundation of the bearing support (9). After the bearing support (9) is assembled on the ground, it is hoisted as a whole and fixed by welding through the embedded parts of the strip foundation after layout and verification. Step 4: Hoist the anti-tension distribution beam (5) above the bearing support (9) and place it close to the bearing main tower (3). Weld steel pipe diagonal braces (13) onto the anti-tension distribution beam (5) and place them close to the bearing main tower (3) to resist the horizontal component force generated by tension. To protect the concrete surface of the main tower, rubber pads (14) are used between the anti-tension distribution beam (5) and the diagonal braces (13) and the bearing main tower (3). Step 5: After the steel strands (7) are cut, install them one by one. One end is anchored to the steel anchor box (8) on the side of the pile foundation (2), and the other end passes through the beam body duct of the anti-tension distribution beam (5) and is anchored to the reaction seat (11) of the distribution beam. The reaction seat (11) is welded to the back of the anti-tension distribution beam (5), and the steel strands (7) pass through the pre-reserved duct in the beam and emerge from the reaction seat (11). Step 6: The steel strands (7) on the left and right sides of the main tower are tensioned simultaneously. For the first tensioning, each bundle of steel strands (7) is considered to have a tension of 50t. Only the steel strands (7) are tensioned. After the tensioning is completed, the steel strands (7) are anchored at the reaction seat (11). Subsequently, the heavy-duty assembly support (4) is continuously monitored, and additional tensioning is considered based on its continued displacement and deformation. Step 7: Install a cable force gauge on the steel strand (7) for cable force monitoring, and use it in conjunction with the daily displacement and deformation monitoring of the structure to judge the structural safety status and the timing of subsequent tensioning; when the daily displacement of the cable force gauge exceeds 2mm, it reaches the warning value, and it is necessary to strengthen the observation and verify the data; when the displacement exceeds 2mm for several consecutive days, it reaches the alarm value, and it is necessary to check whether the instrument is faulty and verify whether there is an error in the data acquisition, and take the next step according to the handling plan.

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