Three-tensioning construction method for stay cables of cable bent tower of extra-large bridge

Abstract

The invention belongs to the technical field of bridge construction, and particularly relates to an extra-large bridge cable tower stay cable three-tensioning construction method. A stay cable of the cable-stayed bridge is divided into three parts including a near tower section, a middle tower section and a far tower section in a hanging and tensioning mode. Stayed cables of the near tower section and the middle tower section are sequentially installed, a high-pressure hose is used for being connected with a tower end control oil pump and an intelligent tensioning jack, and stayed cables of the near tower section and the middle tower section are sequentially and symmetrically tensioned in a grading mode; according to cable force detection and linear detection results, a synchronous tensioning control center and an oil pump system are used for synchronous cable adjustment of stay cables of the near tower section and the middle tower section; beam body installation and stay cable installation of a far tower section are conducted, and after a high-pressure hose is connected with a tower end control oil pump and an intelligent tensioning jack, stayed cables are symmetrically tensioned in a grading mode; according to cable force detection and linear detection results, synchronous cable adjustment of the whole stay cables of the near tower section, the middle tower section and the far tower section is carried out, and the cable force requirement and the bridge linearity are ensured; the linear error and the retraction phenomenon can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and in particular relates to a three-tensioning construction method for a cable tower of an extra-large bridge. Background Art

[0002] The cable-stayed bridge is mainly composed of a pylon, a main beam and a cable. The styles of the pylon include A-type, inverted Y-type, H-type and single column, and the materials can be steel or concrete. The cable can be arranged in a single cable plane, parallel double cable planes or inclined cable planes. The history of cable-stayed bridges can be traced back to the Strömsund Bridge built in Sweden in 1956, with a main span of 182.6 meters. After half a century of development, cable-stayed bridge technology has made great progress, especially after the 1990s, many famous cable-stayed bridges have been built around the world, such as the Sutong Bridge between Nantong and Suzhou in Jiangsu Province, China (main span of 1,088 meters), the Normandy Cable-Stayed Bridge in France (main span of 856 meters), the steel box girder cable-stayed bridge of the South Branch Bridge of the Second Nanjing Yangtze River Bridge (main span of 628 meters), and the Tatara Bridge built in Japan in 1999 (main span of 890 meters).

[0003] The cable-stayed construction technology is an advanced technology used in the construction of cable-stayed bridges. Its emergence and development are to meet the dual needs of modern society for the safety and beauty of bridge construction. This technology mainly guides the load of the bridge to the bridge tower or pier through the cable, so that the bridge components can give full play to their mechanical properties. The emergence of the cable-stayed construction technology has solved some problems in traditional bridge construction and made the construction of large-span bridges possible. With the advancement of science and technology and the continuous accumulation of engineering practice, the cable-stayed construction technology is also constantly developing and improving, providing a more reliable technical guarantee for modern bridge construction.

[0004] At present, the application of cable-stayed bridges has become more and more extensive. Cable-stayed bridges are a kind of multi-times over-statically indeterminate structure, which makes the stress conditions of beams, towers and cables more complicated. In the tensioning process of the cable-stayed cables, an important influencing factor is the unbalanced force, which has a great impact on the construction. The generation of unbalanced force is mainly due to the influence of the cable force of the cable-stayed cables that are tensioned in place later on the same or different layers on the cable force of the cable-stayed cables that are tensioned in place earlier. When the unbalanced force is too large, it will affect the stress conditions of the main structure of the bridge and increase the difficulty of controlling the linear shape of the entire bridge. In the tensioning process of multi-cable planes and multi-layer cable-stayed cables, the generation of unbalanced force is particularly obvious.

[0005] Secondly, the cable-stayed cable may retract during use, which will affect its tensioning effect and the overall performance of the bridge. In addition, the existing anti-retraction technology for the cable-stayed cable cannot be combined with the intelligent tensioning control system to prevent retraction whenever the cable stops.

[0006] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0007] In order to solve the above problems existing in the prior art, the present invention provides a three-tensioning construction method for a cable tower of an extra-large bridge.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A three-tensioning construction method for cable towers of a super-large bridge comprises the following steps: installing beam bodies and cable stays of a near-tower section, a middle-tower section and a far-tower section, and synchronously adjusting the cable stays of the three sections of the near-tower section, the middle-tower section and the far-tower section according to cable force detection and linearity detection results to ensure cable force requirements and bridge linearity.

[0010] Furthermore, the steps are divided into the following sub-steps:

[0011] S1: The cable-stayed bridge is divided into three parts: the near-tower section, the middle-tower section and the far-tower section;

[0012] S2: Install the cable-stayed cables near the tower. After the cable-stayed cables are installed, the intelligent tensioning jacks, the tower end control oil pumps and the data acquisition devices of the synchronous tensioning control center are numbered and assembled, and then the cable-stayed cables near the tower are tensioned symmetrically in stages.

[0013] S3: Install the beams of the middle tower section and the stay cables, use a high-pressure hose to connect the tower end control oil pump and the intelligent tensioning jack, and then perform graded and symmetrical tensioning of the stay cables;

[0014] S4: After the installation and tensioning of the stay cables in the middle tower section, the bridge cable force and linearity tests are carried out in the near-tower section and the middle tower section, and the connection between the synchronous tensioning control center, the tower end control oil pump and the intelligent tensioning jack is established at the same time;

[0015] S5: Based on the cable force test and linearity test results, use the synchronous tensioning control center and control oil pump system to synchronously adjust the cables near the tower section and the middle tower section to ensure the cable force requirements and bridge linearity;

[0016] S6: After the near-tower section and the middle-tower section are tensioned and adjusted synchronously, the beams and the inclined cables of the far-tower section are installed using the same construction process as S2. The inclined cables are then tensioned symmetrically in stages by connecting the tower end control oil pump and the intelligent tensioning jack using a high-pressure hose.

[0017] S7: After the installation and tensioning of the last pair of inclined cables are completed, the same construction process as S4 is used to start the overall bridge cable force detection, linear detection and establishment of the "control center-oil pump-jack" system of the near tower section, middle tower section and far tower section;

[0018] S8: Using the same construction technology as S5, according to the cable force test and linearity test results, synchronous cable adjustment is carried out on the three sections of the near tower section, the middle tower section and the far tower section to ensure the cable force requirements and bridge linearity;

[0019] S9: Complete the tensioning construction of the cable-stayed cables of the entire bridge.

[0020] Furthermore, in S1, the installation and fixation of No. 1 to No. 3 inclined cables and beams are set as the near-tower section, and the remaining inclined cables and beams are divided into the middle-tower section and the far-tower section respectively, and separated according to the hanging order.

[0021] Furthermore, the step of symmetrically tensioning the stay cables in step S2 comprises the following sub-steps:

[0022] S21: Install the control oil pump, establish the "jack-oil pump" system and connect the system to the computer for real-time recording, and control the tension force through "oil pressure-force value";

[0023] S22: After the beam end cable is anchored, the tower end is tensioned. The same group of four cables are tensioned synchronously and symmetrically. The tensioning is controlled by tensioning force and elongation. The tensioning control force is the main control force. The graded tensioning procedure is: 0-0.2σ-0.5σ-0.7σ-1σ;

[0024] S23: During the cable-stayed cable tensioning construction process, the cable tower displacement and main beam monitoring elevation are monitored synchronously.

[0025] Furthermore, the overall synchronous tensioning of the stay cables in S5 comprises the following sub-steps:

[0026] S51: Install and debug on-site equipment. After the cable stays are tensioned in stages, establish a control oil pump, a synchronous tensioning control center, and a synchronous tensioning system for intelligent tensioning jacks according to the bridge inspection results;

[0027] S52: Pre-tension each cable to eliminate the relaxation and initial deformation inside the cable. According to the real-time monitoring data, make preliminary adjustments to the cable to make it close to the tension required by the design.

[0028] S53: Gradually tension each cable until the tensioning force required by the design is reached. During the tensioning process, the cable force changes are continuously monitored, and the tensioning speed and tension are adjusted as needed. For cables with excessive tension, appropriate cable release operations are performed to ensure that the tension is within the design range.

[0029] S54: Check the tensioning data controlled by the master control computer of the on-site synchronous tensioning control center with the data of the intelligent tensioning jack hydraulic equipment to ensure that the data of the two are consistent;

[0030] S55: Perform benchmark calibration of instruments and equipment to ensure that all equipment is in normal working condition, and record the deflection displacement of the beams on both sides of the tower body and the longitudinal displacement offset of the tower body;

[0031] S56: Determine the influencing factors according to the computer control terminal and the design plan, and then analyze the influencing factors to determine the fine-tuning plan for the overall synchronous tensioning of the inclined cables for fine-tuning;

[0032] S57: Tension the cables in place according to the final bridge tension. Hold the cables for 24 hours after on-site tensioning and observation. The deviation between the final on-site result and the predicted value is analyzed by theoretical calculation. When the deviation is within the allowable error range, the entire tensioning process is considered to be completed. Record, write and organize the final tensioning report.

[0033] Furthermore, it includes an intelligent tensioning jack, which is arranged on the beam body and is used to tension the inclined cable; the intelligent tensioning jack includes:

[0034] An outer cylinder body and a piston assembly, wherein the piston assembly is located in the oil chamber of the outer cylinder body;

[0035] An anchoring plate, located at one side of the extended end of the piston assembly and used to fix the inclined cable, and the piston assembly drives the anchoring plate to reciprocate;

[0036] The locking assembly is located outside the outer cylinder body, one end of which is connected to the outer cylinder body, and the other end of which is connected to the anchoring sheet, and is used to lock the position of the anchoring sheet after it is moved.

[0037] The intelligent tensioning jack comprises an outer cylinder body, wherein the outer cylinder body is provided with a piston rod and an oil chamber which can slide up and down, a displacement measuring plate is provided at the upper end of the piston rod, a two-way limit clamp is arranged in the displacement measuring plate, a pad is placed in the displacement measuring plate, an anchor plate is supported on the pad plate, and the anchor plate fixes the steel strand through the unidirectional displacement clamp, the clamping assembly comprises an outer telescopic rod, an inner telescopic rod, a force screw nut and an anchor screw, the anchor plate is fixed with the outer telescopic rod through the anchor screw, the inner telescopic rod is arranged in the outer telescopic rod, the outer telescopic rod has a sliding channel, the upper part of the inner telescopic rod protrudes outward from the sliding channel, so that the inner telescopic rod cannot be separated from the outer telescopic rod, the inner telescopic rod is provided with a thread, a force screw nut is provided on the inner telescopic rod, the displacement measuring plate is externally connected with a linear displacement sensor, the hole in the oil chamber is connected with an oil pressure sensor, the lower end of the oil chamber is provided with an oil chamber bottom cover, and a jack base is provided under the oil chamber bottom cover.

[0038] Furthermore, the hole in the oil chamber is connected to an oil pressure sensor.

[0039] Furthermore, in step S53, the piston rod is moved upward by delivering oil into the oil chamber, driving the displacement measuring plate, the gasket and the anchor plate at the upper end of the piston rod to move upward together. The displacement measuring plate is provided with the bidirectional limit clip to fix the displacement measuring plate on the steel strand. As the steel strand moves, the displacement measuring plate is provided with a gasket to protect the displacement measuring plate and the anchor plate. The anchor plate is provided with the unidirectional displacement clip to limit the steel strand to move only upward.

[0040] Furthermore, when the piston rod moves upward, the steel strand is tensioned, and the anchor plate drives the outer telescopic rod to move upward through the anchor screw. When the anchoring length is reached, the piston rod of the intelligent tensioning jack stops moving upward, and the force screw nut is rotated upward to reach the lower end of the outer telescopic rod at this stage, giving the outer telescopic rod a force point, and the anchor plate is limited by the force screw nut and the anchor screw.

[0041] The beneficial effects of the present invention are:

[0042] (1) When tensioning in stages, by starting from the bottom of the tower and gradually tensioning towards the middle and top of the tower, it is possible to ensure that the tower can maintain sufficient stability at each stage. This gradually stable construction method helps reduce the risk of structural deformation or stress concentration caused by one-time tensioning;

[0043] (2) The application of the intelligent synchronous tensioning system and the combination of the three tensioning construction processes have significantly shortened the construction period and improved the construction quality. Not only has the oil pressure of the intelligent tensioning jack and the tensioning amount of the inclined cable been digitized, but also the anti-retraction and intelligent tensioning have been combined to prevent the anchor plate from losing its tensioning force and causing the inclined cable to retract after the tensioning of the inclined cable is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0045] Figure 1 It is the tensegrity tensioning flow chart of the present invention;

[0046] Figure 2 It is a synchronous tensioning flow chart of the present invention;

[0047] Figure 3 This is a flow chart of hierarchical symmetrical tensioning of the stay cable of the present invention;

[0048] Figure 4 It is a schematic diagram of the bridge near the tower section of the present invention;

[0049] Figure 5 It is a schematic diagram of the near-tower section and the middle-tower section of the bridge of the present invention;

[0050] Figure 6 It is a schematic diagram of the near-tower section, the middle-tower section and the far-tower section of the bridge of the present invention;

[0051] Figure 7 This is an example diagram of the intelligent synchronous tensioning construction arrangement of the present invention;

[0052] Figure 8 It is a schematic diagram of the staged tensioning construction of the present invention;

[0053] Fig. 9 It is a schematic diagram of the intelligent tensioning jack equipment of the present invention.

[0054] Explanation of the reference numerals in the accompanying drawings: 1. Synchronous tensioning control center; 2. Control oil pump; 3. Intelligent tensioning jack; 31. Piston rod; 32. Outer cylinder body; 33. Anchor plate; 34. Outer telescopic rod; 35. Inner telescopic rod; 36. Force screw nut; 37. Anchor screw; 38. Displacement measuring plate; 39. Linear displacement sensor; 310. Oil pressure sensor; 311. Oil chamber bottom cover; 312. Jack base; 313. One-way displacement clip; 314. Pad; 315. Oil chamber; 316. Two-way limit clip; 4. Cable; 5. Beam; 6. Tower body; 7. High-pressure hose; 8. Near tower section; 9. Middle tower section; 10. Far tower section. DETAILED DESCRIPTION

[0055] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0056] like Figure 1-9 As shown, a three-tensioning construction method of a cable tower of a super-large bridge of the present invention comprises the following steps:

[0057] S1: The cable-stayed bridge is hung and tensioned in three parts: a near-tower section 8, a middle-tower section 9 and a far-tower section 10;

[0058] S2: Install the inclined cables 4 near the tower section 8. After the inclined cables 4 are installed, the intelligent tensioning jacks 3, the tower end control oil pump 2 and the data acquisition device of the synchronous tensioning control center 1 are numbered and matched, and then the inclined cables 4 near the tower section 8 are tensioned symmetrically in stages;

[0059] S3: Install the beam 5 of the bridge body of the middle tower section 9 and the inclined cables 4, use a high-pressure hose 7 to connect the tower end control oil pump 2 and the intelligent tensioning jack 3, and then perform graded and symmetrical tensioning of the inclined cables 4;

[0060] S4: After the inclined cable 4 of the middle tower section 9 is installed and tensioned, the bridge cable force detection and linear detection are carried out at the near-tower section 8 and the middle tower section 9, and at the same time, the connection between the synchronous tensioning control center 1, the tower end control oil pump 2 and the intelligent tensioning jack 3 is established;

[0061] S5: According to the cable force detection and linearity detection results, the synchronous tensioning control center 1 and the control oil pump 2 system are used to synchronously adjust the inclined cables 4 of the near-tower section 8 and the middle-tower section 9 to ensure the cable force requirements and the linearity of the bridge;

[0062] S6: After the near tower section 8 and the middle tower section 9 are tensioned and adjusted synchronously, the beam body 5 and the inclined cables 4 of the far tower section 10 are installed using the same construction process as S2, and then the high-pressure hose 7 is used to connect the tower end control oil pump 2 and the intelligent tensioning jack 3, and then the inclined cables 4 are tensioned symmetrically in stages;

[0063] S7: After the installation and tensioning of the last pair of inclined cables 4 are completed, the same construction process as S4 is adopted to start the overall bridge cable force detection, linear detection and establishment of the "control center-oil pump-jack" system of the near tower section 8, the middle tower section 9 and the far tower section 10;

[0064] S8: Using the same construction technology as S5, according to the cable force test and linearity test results, synchronously adjust the three sections of the inclined cable 4 of the near tower section 8, the middle tower section 9 and the far tower section 10 to ensure the cable force requirements and bridge linearity;

[0065] S9: Complete the tensioning construction of 4 cables of the entire bridge.

[0066] Specifically, it is necessary to place two tower-end control oil pumps 2 on both sides of the cable tower, and connect them to the tower-end intelligent tensioning jacks 3 with high-pressure hoses 7 to control the tensioning of the No. 1 to 3 inclined cables 4 on the corresponding sides. When the tensioning of the No. 4 cable is started, three pairs of control oil pumps 2 are set again and placed on both sides of the cable tower, and connected to the tower-end intelligent tensioning jacks 3 with high-pressure hoses 7 to control the tensioning of the No. 4 to 5, No. 6 to 7 and No. 8 inclined cables 4 on the corresponding sides. At the same time, the control oil pumps 2 set this time need to cooperate with the control oil pumps 2 set for the first time to control the inclined cables 4 of the near tower section 8 and the middle tower section 9. To determine the cable tension and reduce the cable adjustment caused by linear problems, 5 pairs of control oil pumps 2 are finally set and placed on both sides of the cable tower. At this time, there are 9 control oil pumps 2 at each end of the cable tower, and the last 5 pairs of control oil pumps 2 are used to control the tensioning of the inclined cables 4 No. 9, 10, 11, 12, 13, 14 and 15 on the corresponding sides. At the same time, the 5 pairs of control oil pumps 2 set this time need to cooperate with the control oil pumps 2 set for the first time and the control oil pumps 2 set for the second time to determine the cable tension of the inclined cables 4 of the near tower section 8, the middle tower section 9 and the far tower section 10 to reduce the cable adjustment caused by linear problems. When using intelligent tensioning, the cable 4 displacement sensor and oil pressure sensor 310 on the intelligent tensioning jack 3 of each cable 4 transmit the mechanical data of the tensioning amount of the cable 4 and the oil pressure data of the intelligent tensioning jack 3 to the control center, and then the staff will issue a tensioning or cable-releasing instruction to the corresponding tower end tensioning control oil pump 2 based on the design value, mechanical data and oil pressure data, and gradually tension each cable 4 until the tensioning force required by the design is reached. During the tensioning process, the changes in the cable force are continuously monitored, and the tensioning speed and tensioning force are adjusted as needed. When all the cables 4 have reached or are close to the tensioning force required by the design, fine adjustments are made to ensure that the tension distribution of each cable 4 is uniform and meets the design requirements. After the adjustment is completed, each cable 4 is anchored to fix its tension.

[0067] Among them, bridge linear detection refers to the measurement of geometric parameters and structural morphology such as length, width, height, vertical elevation, lateral level and curvature of the bridge to understand the actual state and deformation of the bridge. The main purpose of bridge linear detection is to obtain the geometric dimensions and structural morphology data of the bridge to evaluate the current state of the bridge, monitor its deformation, and predict possible destructive deformation. These data provide an important basis for bridge design optimization, construction control, maintenance and reinforcement, and safety assessment. The main purpose of bridge cable force detection is to monitor and evaluate the stress state of the bridge cable structure (such as inclined cables, suspension cables, etc.) to ensure that the cable force is within the design allowable range, thereby ensuring the overall stability and safety of the bridge.

[0068] By combining the intelligent tensioning jack 3 with the control center, not only the automation and precise control of the tensioning process are achieved, but also the controllability of construction quality is improved through real-time monitoring and data analysis.

[0069] When tensioning in stages, by starting from the bottom of the tower and gradually tensioning towards the middle and top of the tower, it is possible to ensure that the tower maintains sufficient stability at each stage. This gradual stabilization construction method helps reduce the risk of structural deformation or stress concentration caused by one-time tensioning.

[0070] The advantages of the first stage are mainly concentrated on the accuracy of the initial tensioning and the stability of the tower bottom. Through the intelligent synchronous tensioning system, the first stage can accurately control the tensioning force and tensioning sequence. This accuracy ensures the stability and uniformity of the tower bottom during the initial tensioning process;

[0071] The second phase focuses on strengthening the overall stability of the tower and optimizing the cable force distribution by strengthening the tensioning. On the basis of ensuring the stability of the bottom of the tower in the first tensioning phase, the second phase further enhances the overall stability of the tower by strengthening the tensioning of the middle of the tower. This gradually stable construction method helps reduce the risk of structural deformation and stress concentration;

[0072] The third stage is the final stage, and its advantages are to ensure the final stability of the cable tower structure, fully control the construction quality and perfect safety protection measures. The third stage achieves the final optimization and adjustment of the cable force through the final tensioning of the top of the cable tower and the comprehensive control of the tensioning process, ensuring the stability and safety of the cable tower in long-term use.

[0073] The application of the intelligent synchronous tensioning system and the combination of the three tensioning construction processes have significantly shortened the construction period and improved the construction quality. Not only can the oil pressure of the intelligent tensioning jack 3 and the tensioning amount of the inclined cable 4 be digitized, but also the anti-retraction and intelligent tensioning can be combined to prevent the anchor plate 33 from losing its tensioning force and causing the inclined cable 4 to retract after the jack is tensioned.

[0074] Among them, in S1, the installation and fixation of No. 1 to No. 3 inclined cables 4 and beams 5 are set as the near-tower section 8, and the remaining inclined cables 4 and beams 5 are divided into two halves and set as the middle-tower section 9 and the far-tower section 10 respectively, and are separated according to the hanging order.

[0075] The step of symmetrically tensioning the stay cables 4 in step S2 includes the following sub-steps:

[0076] S21: Install and control the oil pump 2, establish a "jack-oil pump" system and connect the system to the computer for real-time recording, and control the tension force through "oil pressure-force value";

[0077] S22: After the beam end inclined cables 4 are anchored, the tower end is tensioned. The same group of four inclined cables 4 are tensioned synchronously and symmetrically. The tensioning is controlled by tensioning force and elongation, with tensioning control force as the main control force. The graded tensioning procedure is: 0-0.2σ-0.5σ-0.7σ-1σ;

[0078] S23: During the construction process of the cable-stayed cable 4 tensioning, the displacement of the cable tower and the main beam monitoring elevation are monitored synchronously.

[0079] The overall synchronous tensioning of the stay cables 4 in S5 includes the following sub-steps:

[0080] S51: Install and debug the on-site equipment. After the stay cables 4 are tensioned in stages, establish a synchronous tensioning system of the control oil pump 2, the synchronous tensioning control center 1 and the intelligent tensioning jack 3 according to the bridge inspection results;

[0081] S52: pre-tensioning each of the inclined cables 4 to eliminate the relaxation and initial deformation inside the cables, and making preliminary adjustments to the inclined cables 4 according to the real-time monitoring data to make them close to the tensioning force required by the design;

[0082] S53: gradually tensioning each of the inclined cables 4 until the tensioning force required by the design is reached. During the tensioning process, the cable force changes are continuously monitored, and the tensioning speed and tensioning force are adjusted as required. For the inclined cables 4 with excessive tension, appropriate cable release operations are performed to ensure that the tension is within the design range.

[0083] S54: Check the tensioning data controlled by the master control computer of the on-site synchronous tensioning control center 1 with the data of the hydraulic equipment of the intelligent tensioning jack 3 to ensure that the data of the two are consistent;

[0084] S55: Perform a benchmark calibration of the instruments and equipment to ensure that all equipment is in normal working condition, and record the deflection displacement of the beams 5 on both sides of the tower body 6 and the longitudinal displacement offset of the tower body 6;

[0085] S56: determining the influencing factors according to the computer control terminal and the design plan, and then analyzing the influencing factors to obtain a fine-tuning plan for the overall synchronous tensioning of the stay cable 4 for fine-tuning;

[0086] S57: Tension the cables in place according to the final bridge tension. Hold the cables for 24 hours after on-site tensioning and observation. The deviation between the final on-site result and the predicted value is analyzed by theoretical calculation. When the deviation is within the allowable error range, the entire tensioning process is considered to be completed. Record, write and organize the final tensioning report.

[0087] Specifically, σ stands for Control Stress, which is a key parameter in the prestressing process. Control Stress refers to the target stress value that the prestressed tendons need to reach during the tensioning process to ensure that the prestressed components can work normally under the design load and meet the design requirements.

[0088] Specifically, the meanings of the various steps in the tensioning procedure are as follows:

[0089] 0: Indicates the initial state before tensioning begins, that is, the prestressed tendons are not subjected to any tensioning stress.

[0090] 0.2σ: It means that the prestressed tendons are tensioned to 20% of the control stress. At this stage, the prestressed tendons are usually preliminarily tensioned to check whether the tensioning equipment and the prestressed tendons are in normal condition.

[0091] 0.5σ: Indicates that the prestressed tendons are further tensioned to 50% of the controlled stress. In this stage, the tensioning stress continues to increase while observing the deformation of the prestressed tendons and components.

[0092] 0.7σ: It means that the prestressed steel bars are stretched to 70% of the controlled stress. At this point, the deformation of the prestressed steel bars and components will increase further, but still need to be kept within a controllable range.

[0093] 1σ: It means that the prestressed tendons are stretched to 100% of the controlled stress, that is, the target tension stress value is reached. At this stage, the tension stress needs to be kept stable for a period of time (such as holding the load for a few minutes) to ensure that the prestressed tendons and components are fully stressed and reach a stable state.

[0094] Furthermore, the intelligent tensioning jack 3 in S2 includes an outer cylinder body 32, a piston rod 31 and an oil chamber 315 that can slide up and down are arranged in the outer cylinder body 32, a displacement measuring plate 38 is arranged at the upper end of the piston rod 31, a bidirectional limit clamp 316 is arranged in the displacement measuring plate 38, a pad 314 is placed in the displacement measuring plate 38, an anchoring plate 33 is supported on the pad 314, the anchoring plate 33 fixes the steel strand through the unidirectional displacement clamp 313, the anchoring plate 33 is fixed with an outer telescopic rod 34 through an anchor screw 37, and the outer telescopic rod 34 is fixed with an outer telescopic rod 34 through an anchor screw 37. An inner telescopic rod 35 is arranged inside the rod 34, and an outer telescopic rod 34 has a sliding hole. The upper part of the inner telescopic rod 35 protrudes outward from the sliding hole, so that the inner telescopic rod 35 cannot be separated from the outer telescopic rod 34. The inner telescopic rod 35 is threaded, and a force-bearing screw nut 36 is arranged on the inner telescopic rod 35. The displacement measuring plate 38 is externally connected to a linear displacement sensor 39, and an oil pressure sensor 310 is connected to a hole in the oil chamber 315. An oil chamber bottom cover 311 is arranged at the lower end of the oil chamber 315, and a jack base 312 is arranged under the oil chamber bottom cover 311.

[0095] During the tensioning stage, oil is transported into the oil chamber 315 to move the piston rod 31 upward, driving the displacement measuring plate 38, the gasket and the anchor plate 33 at the upper end of the piston rod 31 to move upward together. The displacement measuring plate 38 is provided with a bidirectional limit clip 316 to fix the displacement measuring plate 38 on the steel strand. As the steel strand moves, the displacement measuring plate 38 is provided with a gasket to protect the displacement measuring plate 38 and the anchor plate 33. The anchor plate 33 is provided with a unidirectional displacement clip 313 to limit the steel strand to move only upward. When the piston rod 31 moves upward, the steel strand is tensioned. At the same time, the anchor plate 33 drives the outer telescopic rod 34 to move upward through the anchor screw 37. The outer telescopic rod 34 has an inner telescopic rod 35. The outer telescopic rod 34 has a sliding hole. The upper part of the inner telescopic rod 35 protrudes outward from the sliding hole, so that the inner telescopic rod 35 cannot be separated from the outer telescopic rod 34. When the anchoring length is reached, the piston rod 31 of the intelligent tensioning jack 3 stops moving upward. At this time, it is necessary to rotate the force screw nut 36 upward to reach the lower end of the outer telescopic rod 34 at this stage to give the outer telescopic rod 34 a force point. At this time, the anchor plate 33 will not move downward due to the action of the force screw nut 36, and will not move upward due to the action of the anchor screw 37, thereby preventing the intelligent tensioning jack 3 from losing the tensioning force after the tensioning is completed, driving the inclined cable 4 to retract. The intelligence of the intelligent tensioning jack 3 is reflected in: the displacement measuring plate 38 is fixed on the steel strand, and the displacement measuring plate 38 is connected to the outside of the displacement measuring plate 38. The tensioning length of the steel strand can be accurately measured. If the inclined cable 4 still has a small retraction, the steel strand will drive the displacement measuring plate 38 to move downward. At this time, the linear displacement sensor 39 will immediately detect the small displacement, and more accurately know the tensioning amount of the steel strand of the inclined cable 4, so as to estimate the change of the cable force. The oil chamber 315 has a hole that is the same as the oil pressure sensor 310, so as to know the oil pressure value of the intelligent tensioning jack 3 more clearly. The bottom of the intelligent tensioning jack 3 is provided with an oil chamber bottom cover 311, which is conducive to convenient maintenance when the intelligent tensioning jack 3 equipment fails. A jack base 312 is provided under the oil chamber bottom cover 311, and a groove is provided in the base, which is convenient for fixing the intelligent tensioning jack 3 and protecting the main body of the intelligent tensioning jack 3 while making the intelligent tensioning jack 3 better stressed.

[0096] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A three-tensioning construction method for a cable tower of a super-large bridge, characterized in that: The construction method comprises the following steps: installing the beam body (5) and the inclined cable (4) of the near-tower section (8), the middle-tower section (9) and the far-tower section (10); and synchronously adjusting the inclined cables (4) of the three sections of the near-tower section (8), the middle-tower section (9) and the far-tower section (10) according to the cable force detection and linearity detection results to ensure the cable force requirements and the linearity of the bridge.

2. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 1 is characterized in that: The steps are divided into the following sub-steps: S1: The cable stays (4) of the cable-stayed bridge are hung and tensioned into three parts: a near-tower section (8), a middle-tower section (9) and a far-tower section (10); S2: Install the inclined cables (4) of the near-tower section (8), and after the inclined cables (4) are installed, number and match the intelligent tensioning jacks (3), the tower end control oil pump (2) and the data acquisition devices of the synchronous tensioning control center (1), and then perform graded and symmetrical tensioning on the inclined cables (4) of the near-tower section (8); S3: Install the beam body (5) of the bridge body of the middle tower section (9) and the inclined cables (4), use a high-pressure hose (7) to connect the tower end control oil pump (2) and the intelligent tensioning jack (3), and then perform graded and symmetrical tensioning of the inclined cables (4); S4: After the inclined cables (4) of the middle tower section (9) are installed and tensioned, bridge cable force detection and linear detection are performed at the near-tower section (8) and the middle tower section (9), and at the same time, the connection between the synchronous tensioning control center (1), the tower end control oil pump (2) and the intelligent tensioning jack (3) is established; S5: Based on the cable force detection and linearity detection results, the synchronous tensioning control center (1) and the control oil pump (2) system are used to synchronously adjust the inclined cables (4) of the near-tower section (8) and the middle-tower section (9) to ensure the cable force requirements and bridge linearity; S6: After the near-tower section (8) and the middle-tower section (9) are tensioned and adjusted synchronously, the beam body (5) and the inclined cables (4) of the far-tower section (10) are installed using the same construction process as S2, and then the tower end control oil pump (2) and the intelligent tensioning jack (3) are connected by a high-pressure hose (7), and the inclined cables (4) are tensioned symmetrically in stages; S7: After the installation and tensioning of the last pair of inclined cables (4) are completed, the same construction process as S4 is used to start the overall bridge cable force detection, linear detection and establishment of the "control center-oil pump-jack" system of the near tower section (8), the middle tower section (9) and the far tower section (10); S8: Using the same construction technology as S5, according to the cable force test and linearity test results, synchronously adjust the three sections of the inclined cable (4) near the tower section (8), the middle tower section (9) and the far tower section (10) to ensure the cable force requirements and bridge linearity; S9: Complete the tensioning construction of the bridge's cable stays (4).

3. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 2 is characterized in that: In the above S1, the installation and fixation of No. 1 to No. 3 inclined cables (4) and beam bodies (5) are set as the near-tower section (8), and the remaining inclined cables (4) and beam bodies (5) are divided into two halves and set as the middle-tower section (9) and the far-tower section (10), and the sections are separated according to the order of hanging.

4. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 2 is characterized in that: The step of symmetrically tensioning the inclined cables (4) in S2 comprises the following sub-steps: S21: Install the control oil pump (2), establish a "jack-oil pump" system and connect the system to the computer for real-time recording, and control the tension force through "oil pressure-force value"; S22: After the beam end inclined cables (4) are anchored, the tower end is tensioned. The four inclined cables (4) in the same group are tensioned synchronously and symmetrically. The tensioning is controlled by tensioning force and elongation, with tensioning control force as the main factor. The graded tensioning procedure is: 0-0.2σ-0.5σ-0.7σ-1σ; S23: During the tensioning construction process of the cable stays (4), the displacement of the tower body (6) and the main beam monitoring elevation are monitored synchronously.

5. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 2 is characterized in that: The overall synchronous tensioning of the stay cables (4) in S5 comprises the following sub-steps: S51: installing and debugging on-site equipment, after the stay cables (4) are tensioned in stages, establishing a synchronous tensioning system of a control oil pump (2), a synchronous tensioning control center (1) and an intelligent tensioning jack (3) according to the bridge inspection results; S52: pre-tensioning each inclined cable (4) to eliminate relaxation and initial deformation inside the cable, and making preliminary adjustments to the inclined cable (4) based on real-time monitoring data to make it close to the tension required by the design; S53: gradually tensioning each inclined cable (4) until the tensioning force required by the design is reached. During the tensioning process, the change of the cable force is continuously monitored, and the tensioning speed and the tensioning force are adjusted as required. For the inclined cable (4) with excessive tension, the cable is appropriately released to ensure that the tension is within the design range. S54: Check the tensioning data controlled by the master control computer of the on-site synchronous tensioning control center (1) with the data of the hydraulic equipment of the intelligent tensioning jack (3) to ensure that the data of the two are consistent; S55: Performing a reference calibration of the instruments and equipment to ensure that all the equipment is in normal working condition, and recording the deflection displacement of the beams (5) on both sides of the tower body (6) and the longitudinal displacement offset of the tower body (6); S56: determining the influencing factors according to the computer control terminal and the design plan, and then analyzing the influencing factors to obtain a fine-tuning plan for the overall synchronous tensioning of the stay cable (4) for fine-tuning; S57: Tension the cables in place according to the final bridge tension. Hold the cables for 24 hours after on-site tensioning and observation. The deviation between the final on-site result and the predicted value is analyzed by theoretical calculation. When the deviation is within the allowable error range, the entire tensioning process is considered to be completed. Record, write and organize the final tensioning report.

6. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 5 is characterized in that: The invention comprises an intelligent tensioning jack (3), wherein the intelligent tensioning jack (3) is arranged on a beam body and is used for tensioning a stay cable (4); the intelligent tensioning jack (3) comprises: An outer cylinder body (32) and a piston assembly, wherein the piston assembly is located in an oil chamber (315) of the outer cylinder body (32); An anchoring plate (33) is located on one side of the protruding end of the piston assembly and is used to fix the inclined cable (4). The piston assembly drives the anchoring plate (33) to move back and forth. The locking assembly is located outside the outer cylinder body (32), one end of which is connected to the outer cylinder body (32) and the other end of which is connected to the anchoring plate (33), and is used to lock the position of the anchoring plate (33) after movement.

7. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 6 is characterized by: The intelligent tensioning jack (3) has a piston rod (31) and an oil chamber (315) that can slide up and down in the outer cylinder body (32), a displacement measuring plate (38) is provided at the upper end of the piston rod (31), a bidirectional limiting clamp (316) is provided in the displacement measuring plate (38), a pad (314) is placed in the displacement measuring plate (38), an anchoring plate (33) is supported on the pad (314), the anchoring plate (33) fixes the steel strand through the unidirectional displacement clamp (313), the clamping assembly comprises an outer telescopic rod (34), an inner telescopic rod (35), a force screw nut (36) and an anchoring screw (37), the anchoring plate (33) is fixed by the unidirectional displacement clamp (313), and the anchoring plate (33) is fixed by the unidirectional displacement clamp (313). An outer telescopic rod (34) is fixed by an anchor screw (37), an inner telescopic rod (35) is arranged inside the outer telescopic rod (34), the outer telescopic rod (34) has a sliding hole, the upper part of the inner telescopic rod (35) protrudes outward from the sliding hole, so that the inner telescopic rod (35) cannot be separated from the outer telescopic rod (34), the inner telescopic rod (35) has a thread, a force screw nut (36) is arranged on the inner telescopic rod (35), the displacement measuring plate (38) is externally connected to a linear displacement sensor (39), the lower end of the oil chamber (315) has an oil chamber bottom cover (311), and a jack base (312) is arranged under the oil chamber bottom cover (311).

8. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 7 is characterized in that: The hole in the oil chamber (315) is connected to an oil pressure sensor (310).

9. The three-tensioning construction method for the cable tower of a super-large bridge according to claim 8 is characterized in that: In step S53, the oil is transported into the oil chamber (315) so that the piston rod (31) moves upward, driving the displacement measuring plate (38), the gasket and the anchor plate (33) at the upper end of the piston rod (31) to move upward together. The displacement measuring plate (38) has the bidirectional limiting clip (316) to fix the displacement measuring plate (38) on the steel strand. As the steel strand moves, the displacement measuring plate (38) has the gasket to protect the displacement measuring plate (38) and the anchor plate (33). The anchor plate (33) has the unidirectional displacement clip (313) to limit the steel strand to move only upward.

10. The method for three-tensioning construction of cable towers of a super-large bridge according to claim 9, characterized in that: When the piston rod (31) moves upward, the steel strand is tensioned, and the anchoring plate (33) drives the outer telescopic rod (34) to move upward together through the anchoring screw (37). When the anchoring length is reached, the piston rod (31) of the intelligent tensioning jack (3) stops moving upward, and the force screw nut (36) is rotated upward to reach the lower end of the outer telescopic rod (34) at this stage, giving the outer telescopic rod (34) a force point, and the anchoring plate (33) is limited by the force screw nut (36) and the anchoring screw (37).

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