Symmetrical suspended pouring efficient construction method for main beam of cable-stayed bridge based on front fulcrum cable-stayed hanging basket

Abstract

The invention discloses a cable-stayed bridge girder symmetric suspended pouring efficient construction method based on a front fulcrum cable-stayed hanging basket, which adopts a front fulcrum hanging basket symmetric suspended pouring mode for construction, and comprises the following steps: A, mounting a hanging basket; b, mounting a bottom film; c, mounting and tensioning the stay cable; d, mounting reinforcing steel bars and prestressed pipelines; e, end film installation; f, concrete pouring; g, pre-stress construction in the beam body; h, the hanging basket is placed downwards, then walking anchoring is conducted on the hanging basket, and the formwork is lifted and installed; the hanging basket is installed in a hoisting mode after being assembled, and a corresponding assembling place is selected according to the position of a pier; the concrete used during concrete pouring is good in flowability, workability, water-retaining property, cohesiveness and volume weight, and the concrete is uniformly put into a mold and is vibrated and compacted during concrete pouring; during prestress tensioning, multiple times of tensioning circulation are conducted; a deviation rectifying mechanism is arranged on the rear portion of the hanging basket. The problems that an existing hanging basket is prone to deviation due to errors and stability in erection, uneven concrete pouring and prestress loss are solved.

Description

Technical Field

[0001] The invention relates to the field of main beam construction, in particular to an efficient construction method for symmetrical suspended casting of a main beam of a cable-stayed bridge based on a front support cable hanging basket. Background Art

[0002] Cable-stayed hanging basket construction is a construction method used for cantilever casting of large-span bridges, especially for the main beam construction of cable-stayed bridges and large-span bridges. The cable-stayed hanging basket used in it belongs to a complex three-dimensional force system in space. When the equipment is in working state (casting concrete), the C-shaped hook and three sets of slings on the middle crossbeam are used as the rear fulcrum to hang on the poured main beam segment; the inclined cable is used as the front fulcrum and the cable is anchored on the anchor groove of the curved beam at the front end of the hanging basket through the tensioning system to form a concrete load-bearing platform for the construction blocks, which meets the needs of construction operations in each process. Its main features include: 1. The equipment is light in weight, only 0.37 times the structural load of the block to be poured (the design control index is generally ≤0.42 times), which is much smaller than the conventional rear support hanging basket, which can effectively ensure the construction quality and improve the economic benefits.

[0003] 2. The construction speed can reach one standard express every 6 days, which is at the leading level among similar bridge construction in China.

[0004] 3. The guying system adopts a spatial simulation parallel cable surface automatic steering correction system, which has high cable positioning accuracy, fast speed, safety and simplicity.

[0005] 4. The formwork system is a self-lifting formwork support integrated system, which is safe and easy to operate, has a fast construction speed and light load.

[0006] 5. The main beam adopts a multifunctional variable-section box, which can effectively reduce the weight of the equipment.

[0007] To put it simply, it is convenient, simple, economical, and can significantly improve the safety and quality of construction.

[0008] Although the cable-stayed basket construction has significant advantages in the construction of long-span bridges, it also has some disadvantages and risks. The following are the main disadvantages of the cable-stayed basket construction: Erection errors and stability issues: During the erection of the hanging basket, erection errors and stability issues may occur, which may affect the subsequent construction; Uneven concrete pouring and prestress loss: During the construction phase, problems such as uneven concrete pouring, loss of prestressing stress, and incomplete grouting are common, which will affect the quality and structural safety of the bridge; During the movement of the hanging basket, it is necessary to ensure that the moving trajectory of the hanging basket is consistent with the axis of the beam to avoid deviation or shaking, otherwise it may cause damage to the beam.

[0009] Therefore, in view of the above-mentioned defects, it is necessary to improve the existing cable hanging basket construction plan. Summary of the invention

[0010] The purpose of the present invention is to provide a high-efficiency construction method for symmetrical suspended casting of the main beam of a cable-stayed bridge based on a front-support cable hanging basket, so as to solve the existing problems.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions: A highly efficient construction method for symmetrical suspended pouring of the main beam of a cable-stayed bridge based on a front-support cable hanging basket, which adopts a front-support hanging basket symmetrical suspended pouring method, including the following steps: A, hanging basket installation; B, bottom membrane installation; C, inclined cable installation and tensioning; D, steel bar and prestressed pipe installation; E, end membrane installation; F, concrete pouring; G, prestressing construction in the beam body; H, lowering the hanging basket and then carrying out the hanging basket walking anchoring and template lifting installation, and the construction is completed after completion; The hanging basket is installed by hoisting after assembly, and the corresponding assembly site is selected according to the location of the bridge pier; The concrete used in concrete pouring is a concrete with good fluidity, workability, water retention, cohesion and bulk density. The concrete needs to be poured evenly into the mold and then vibrated to make it dense. Prestressing requires multiple tensioning cycles. A deviation correction mechanism is provided at the rear of the hanging basket.

[0012] Firstly, in this method, the hanging basket is installed by hoisting after assembly, and the corresponding assembly site is selected according to the position of the bridge pier, which is not only efficient, but also has small errors and good stability after hoisting. Then, when pouring concrete, concrete with good fluidity, workability, water retention, cohesion and bulk density is used. After the concrete is poured, the surface is covered with geotextile and watered to ensure that the concrete surface is moist and not directly exposed to the sun and rain. The raw materials of the concrete are as follows: 478 parts of cement, 78 parts of fly ash, 675 parts of sand, 1055 parts of crushed stone, 150 parts of water, and 7.2 parts of admixture. The admixture is a polycarboxylic acid high-performance water reducer produced by Sichuan Sanhe Concrete Admixture Co., Ltd. By selecting a suitable water reducer or adjusting the dosage of the water reducer, the initial setting time of the concrete mixture can be reasonably extended to meet the construction time of on-site concrete pouring. The compatibility test of the water reducer and cement is carried out. And by adjusting the composition of the water-reducing agent, the effective initial setting time of the concrete is ensured. The polycarboxylic acid high-efficiency water-reducing agent with stable performance and high water-reducing rate is preferably used, which can effectively reduce the amount of cement used per cubic meter of concrete, thereby reducing the hydration heat temperature rise of the concrete. The crushed stone is 5~25mm continuously graded stone, and the mud content in the crushed stone is ≤1.0%. The concrete made of the above raw materials has good fluidity, workability, water retention, cohesion and bulk density, so it can be well spread evenly, and vibration compaction is also carried out during pouring, which effectively solves the problems of uneven concrete pouring, prestressed tension stress loss, and incomplete grouting during the construction stage. Finally, a correction mechanism is set on both sides of the rear part of the hanging basket, and the correction mechanism can ensure that the moving trajectory of the hanging basket is consistent with the axis of the beam body to avoid deviation or shaking. In summary, this solution has more advantages than the existing technology. As a further preferred embodiment of the present invention, the hanging basket in the hanging basket installation in step A includes a main longitudinal beam, a C-shaped hook, a front cross beam, a middle cross beam, a rear cross beam, a middle anchor rod, a rear anchor rod, a walking reverse roller, a lifting mechanism, a thrust mechanism, a template system and a traction system, wherein the front cross beam, the middle cross beam and the rear cross beam are respectively arranged at the front, middle and rear of the inner side of the main longitudinal beam, the lower part of the C-shaped hook is connected to the middle part of the outer side of the main longitudinal beam, the lower end of the middle anchor rod is connected to the middle cross beam, and the lower end of the rear anchor rod is connected to the middle cross beam. The end is connected to the rear cross beam, the walking counter-roller is rotatably arranged at the tail of the main longitudinal beam, the template system is arranged on the inner side of the main longitudinal beam, the jacking mechanism includes an inner template frame lifting mechanism, a middle anchor rod lifting mechanism and a tail balancing jack, the top of the inner template frame lifting mechanism is connected to the inner template arch frame of the template system, the top surface of the middle anchor rod lifting mechanism is connected to the middle anchor rod, the tail balancing jack is arranged on the top surface of the rear of the main longitudinal beam, and the thrust mechanism is arranged at the rear of the main longitudinal beam.

[0013] The main longitudinal beam of the hanging basket is divided into three sections, namely the arc head, the main longitudinal beam section 1 and the main longitudinal beam section 2. The arc head is installed with the tension distribution beam for tensioning the inclined cable. The C-type hook is a box-shaped section. The C-type hook fulcrum and the track sliding are used at the top to complete the movement of the hanging basket. When the hanging basket is lowered as a whole, the C-type hook falls on the channel steel track of the bridge deck, and the tail reaction wheel rotates in place and is fixed. The tail balance jack is lifted synchronously. Through the temporary reaction device at the outer end of the cast beam section, the reaction wheel at the rear of the hanging basket is used, and the step compound jack is used on the front to realize the movement of the hanging basket. The inner mold support system of the hanging basket adopts the form of an arch frame. The arch frame supports the template through steel pipes, which can realize the overall lowering and raising of the inner mold. A basket monitoring system is also set up at the basket. This system is an interactive information management platform developed for the basket that integrates collection monitoring, recording, analysis, diagnosis, early warning, and statistics. It not only meets the requirements of the national standard GB / T28264-2017 crane basket monitoring system, but also incorporates a variety of crane monitoring, maintenance, management and other practical functions. It is a monitoring system that integrates equipment management and personnel behavior control, and truly implements safety monitoring measures. The system includes a remote data center, a data monitoring system and a video monitoring system. The data monitoring system is mainly composed of a signal collector, which is provided with a zigbee module. The power supply of the signal collector is provided by a UPS power supply. The terminals connected to the signal collector include a wind speed sensor, a lifting encoder, an inclination sensor, a temperature and humidity sensor, a force sensor, and a stress sensor. The power supply of the signal collector is provided by a UPS power supply. An annular hollow force sensor is installed on multiple anchors at the anchors and the middle cross beam of the hanging basket. The signal collector collects the anchoring force of the anchors on both sides and reflects it to the host in real time to measure the force difference on both sides of the hanging basket to prevent accidents caused by uneven force on site. Stress sensors are installed at the beam, rear anchor and other positions. The specific position can be based on the requirements of Party A to install stress sensors at the corresponding positions to monitor the overall stress of the hanging basket in real time. The inclination sensor is installed at the corresponding position by welding to monitor the dual-axis deflection of the point. The inclination sensor signal is centrally transmitted to the host for display through the collector, and an infrared distance sensor is installed at the walking mechanism position by welding to the corresponding position to monitor the forward movement of the hanging basket. The sensor transmits the signal to the host through the collector and displays it, and sets a limit on the host side. When the hanging basket exceeds the limit during operation, the host alarms. Temperature and humidity sensors are arranged on the steel mesh to monitor the temperature of concrete pouring and send signals to the temperature and humidity monitoring system. If the temperature and humidity data of a certain concrete is abnormal, the upper computer software will automatically start the alarm device and notify the relevant technical personnel to handle it. The hanging basket monitoring system collects data through the signal acquisition module, and the human-machine interface performs statistical conversion, and stores, records and displays the equipment operation working time, cumulative working time and work cycle data; The video surveillance system consists of a video display, a hard disk recorder and a camera, and is connected through Ethernet or 4G network. The cameras of the video surveillance system include ball cameras and gun cameras, both of which have infrared functions. The ball camera is a controllable ball camera that conducts video surveillance of the surrounding environment of the hanging basket, while the gun camera monitors specific parts of the hanging basket. The cameras are all set up at the hanging basket site, and the video display and hard disk recorder are arranged next to Party A's electrical control cabinet; because there is a remote data center, the client can access the data through a browser or mobile phone APP, and the remote terminal can obtain field-level data services to realize the query of the working status of the on-site equipment, which can easily increase the number of simultaneous accesses and expand the network.

[0014] The advantages of the hanging basket monitoring system are as follows: (1) Simple structure: The human-machine interface wireless host computer effectively reduces investment and maintenance costs; (2) The entire system uses the signal acquisition box as the main control element and mechanical limit protection to achieve control, making the entire system highly reliable; (3) The entire system can meet the client's inspection requirements and detect the sensor signals at each point in real time to achieve safe construction of the project; (4) The entire system adopts wireless communication mode, which has the advantages of simple installation, fast disassembly, compact structure, and interoperability; (5) Data and video information can be sent to the background through DTU or the Internet, and can be viewed remotely in real time and analyzed in the background to determine the correctness of the operation; (6) The system can have a built-in SMS module, and when there is a major violation of regulations, SMS notifications can be sent to relevant supervisory posts in a timely manner.

[0015] After the above system is set up, the accuracy of the hanging basket installation can be guaranteed, the posture can be adjusted in time during movement, and the overall stress and anchoring conditions of the hanging basket can be monitored in real time.

[0016] As a further preference of the present invention, the installation of the hanging basket in the step A includes the installation of the hanging basket at the pier near the bank of the river channel and the installation of the hanging basket at the pier in the middle of the river channel. The installation of the hanging basket at the pier near the bank of the river channel includes land assembly and hoisting, and the installation of the hanging basket at the pier in the middle of the river channel includes assembly and hoisting on the long-mileage side and assembly and hoisting on the short-mileage side. The assembly in the long-mileage side assembly and hoisting is carried out on the pier, and the assembly in the short-mileage side assembly and hoisting is carried out on the ship.

[0017] When assembling on board, as the number of hanging basket components on board increases, the ship will tilt. When the height difference of the tilt is greater than 10cm, add counterweight in time.

[0018] The boat is docked on the river bank upstream of the bridge pier. The assembly steps are as follows: Step 1: Assemble the hanging basket and install the tire frame.

[0019] The position of the main longitudinal beam of the hanging basket is laid out in the cabin of the sand dredging ship, and the assembly frame is installed. After the frame is installed, the outline of the main longitudinal beam is laid out on the frame, and at the same time, the ship obstacles within the assembly range of the hanging basket are checked and cleared.

[0020] Step 2: Lifting of main longitudinal beam A.

[0021] After the main longitudinal beam outline is laid out and the obstacles on the ship are cleared, the main longitudinal beam A is hoisted. After the single-side main longitudinal beam A is hoisted, four 3t chain hoists are used to fix the main longitudinal beam A on the sand dredging ship to prevent the main longitudinal beam A from capsizing.

[0022] Step 3: Assemble the arc head.

[0023] After the main longitudinal beam A is hoisted and fixed, assemble the arc head. The arc head and the connecting part of the main longitudinal beam A are connected with the matching high-strength bolts. The bolts are fully inserted and tightened manually.

[0024] Step 4: Assemble the front crossbeam.

[0025] After the arc-shaped head is assembled, assemble the front crossbeam. The front crossbeam is divided into three sections and is assembled in sequence from one side to the other side to facilitate the adjustment and alignment of the bolt eyes of the connecting part. The bolts are fully inserted and tightened manually.

[0026] Step 5: Assemble the middle cross beam.

[0027] After the front crossbeam is assembled, assemble the middle crossbeam. The assembly sequence and bolt connection requirements are the same as the front crossbeam.

[0028] Step 6: Assemble the main longitudinal beam B and the rear cross beam.

[0029] After the middle cross beam is assembled, the main longitudinal beam B is hoisted. After the main longitudinal beam B is hoisted, the rear cross beam and its connecting beam are assembled. After the rear cross beam and its connecting beam are assembled, the bolts of each connection are tightened to the design requirements and checked with a torque wrench. The control torque is 864N·m.

[0030] Step 7: Install other components of the hanging basket.

[0031] After the bolts of the connecting parts of the main components of the hanging basket are tightened and checked, install other components such as the inner mold arch frame, formwork support, working platform, etc. of the hanging basket.

[0032] The torque method used in the construction of high-strength bolts during assembly is divided into two tightening stages: initial tightening and final tightening. The initial tightening torque is 30%-50% of the final tightening torque, and the bolts are tightened with the final torque. If the plate layers are thicker and there are more plate stacks, the initially tightened plate layers may not be sufficiently close together.

[0033] The high-strength bolts on a joint should be installed from the middle of the bolt group and tightened one by one. The final tightening should be started from the middle of the bolt group and extended to the surrounding areas to tighten one by one. Each tightening should be marked with different colors of paint to prevent missing tightening. If the joint is connected by high-strength bolts and electric welding, whether to tighten first or weld first should be done in the order specified in the design requirements. If there is no design requirement, the construction process sequence is tightened first and then welded (i.e. bolted first and then welded). The high-strength bolts are finally tightened first and then the welds are welded. The tightening sequence of high-strength bolts is from the part with large rigidity to the unconstrained free end, and from the middle to the surrounding areas in the same node to make the plates fit tightly.

[0034] The precautions for high-strength bolt construction are as follows: 1) The direction of bolt penetration shall be based on the convenience of construction, and each node shall be neat and consistent; 2) Nuts and washers have direction requirements, and bolts and nuts are marked with grades and manufacturers; 3) Due to the narrow space, the high-strength bolt wrench is not suitable for operation. It can be installed by raising the sleeve or using a manual wrench; 4) If the high-strength bolts are over-tightened, they should be replaced and discarded, and they should not be reused; 5) Gas cutting is not allowed for misaligned holes or leaky holes during installation; 6) Stop working when the temperature is below -10°C; stop working when the friction surface is wet or exposed to rain or snow; 7) High-strength bolts should be kept in factory condition as much as possible during packaging, transportation and use; 8) The torque wrench must be calibrated before construction. When tightening, large hexagonal bolts should be tightened according to the construction torque, and torsion shear bolts should be tightened with a special electric wrench; 9) It is strictly forbidden to throw bolts, nuts and washers randomly during high-altitude construction to avoid falling and injuring people.

[0035] After the basket is assembled, it needs to be transported on water. After the basket is assembled on the ship, the center of gravity of the basket is located at about 1 / 4 of the ship contact surface, and there is a certain degree of eccentricity. Before transportation, sandbags are used to counterweight the assembled ship. The stacking height of the sandbags during the counterweight process does not exceed 1.2m. Then tie another transport balance boat to the other side of the assembled ship.

[0036] There is a certain amount of partial load in the hanging basket during transportation. Sandbags are used to counterweight the assembled ship before transportation. F1*L1+F3*L3=F2*L2. The sandbag stacking height can be calculated by the above formula. The sandbags are fixed with anti-fall nets, and a threaded steel bar is welded every one meter on the edge of the ship as a guardrail.

[0037] Before starting transportation, slowly drive the boat to deep water and observe the posture of the hull. If the transport ship tilts too much, drive back to the shore in time to re-fix the balancing boat to ensure that the hull is stable during transportation, and then drive the boat to the designated position for lifting the hanging basket.

[0038] After the boat is driven to the designated position and fixed, the continuous jack and lifting steel strand are installed, and each steel strand is pre-tightened by using a 25T hydraulic single pumping jack. After the pre-tightening is completed, the stroke of 4 jacks is debugged. Before the basket is lifted, the temporary passage and temporary anchoring device between the basket and the hull platform are released. When the basket is lifted, the basket is first lifted 10cm away from the platform and temporarily lifted to allow the basket to automatically balance vertically under the action of its own weight. At the same time, the surrounding conditions of the basket are checked. After the basket automatically balances vertically and the surrounding conditions are checked, the basket is lifted continuously normally. During the whole process of the basket lifting, 4 people are arranged on the main beam to observe the working status of the continuous jacks at the upstream and downstream basket hanging points, and another 4 people are arranged on board to observe the lifting balance of the basket. When the basket is lifted to the anchor installation height range, the continuous jack lifting is stopped, the basket's own anchor lifting system is installed, and the basket is lifted into place using the basket's own anchor lifting system. After the basket is lifted into place, the continuous jack lifting system and lifting bracket are removed, and the remaining anchor system of the basket is installed.

[0039] The specific steps of the above hanging basket lifting process are as follows: Step 1: Dock the transport ship at the designated location and anchor it stably.

[0040] When the transport ship is docked, use the 1# lifting hole to lower the plumb line for positioning, and stop the ship and drop anchor after the 1# lifting hole is aligned with the lifting hole of the hanging basket.

[0041] Step 2: After the transport ship is fixed, install the continuous jacks and lift the steel strands, and use the hydraulic single pump to pre-tighten each steel strand. After pre-tightening, debug the stroke of the four jacks.

[0042] Step 3: Before lifting the hanging basket, remove the temporary passage and temporary anchoring device between the hanging basket and the platform.

[0043] When lifting the hanging basket, first lift the hanging basket 10cm away from the platform and temporarily lift it to allow the hanging basket to automatically balance and stand upright under its own weight. At the same time, check the surrounding conditions of the hanging basket. After the hanging basket automatically balances and stands upright and the surrounding conditions are checked, disassemble the transport ship and withdraw from the installation position. Use one of the ships to transport the main longitudinal beam crane platform to the installation position and install it using a tower crane. Step 4: After the main longitudinal beam hanging platform is installed in place, lift the hanging basket normally and continuously.

[0044] During the whole process of the basket lifting, 4 people were arranged on the main beam to observe the working status of the continuous jacks at the upstream and downstream basket lifting points. Another 4 people were arranged on board to observe the lifting balance of the basket.

[0045] Step 5: When the basket is lifted to within the anchor installation height range, stop continuous jack lifting.

[0046] Install the hanging basket's own anchor rod lifting system, and use the hanging basket's own anchor rod lifting system to lift the hanging basket into place.

[0047] Step 6: After the hanging basket is lifted into place, remove the continuous jack lifting system and lifting bracket, and install the remaining anchoring system of the hanging basket.

[0048] Finally, in order to ensure construction safety, the raw material steel bars are used to pile up in different areas for preloading of the hanging basket, and the stress condition after the hanging basket is poured into concrete is simulated to observe the settlement and deformation. The construction steps of the hanging basket preloading are: preloading preparation (conduct technical explanation, arrange construction personnel, arrange mechanical equipment, prepare loading preloading materials → fix the hanging basket in place → inspect and accept the hanging basket → mark the observation points → load in stages → observe and record → let it stand still and observe and record → collate and analyze data → report on preloading test results → adjust the bottom formwork of the hanging basket.

[0049] The preloading is carried out in stages, with 50% and 110% loading. After each level of loading, the settlement is measured after 3 hours of static loading and records are kept. The preloading should be uniform during preloading to avoid eccentric compression of the bracket causing instability of the bracket. The loading sequence is consistent with the construction sequence of cast-in-place concrete. Concrete construction is continuously poured in longitudinal sections and horizontal layers. According to the loading sequence of the main longitudinal beam, transverse partition, last top plate and wing plate. When preloading, it should start from the bottom and expand and rise layer by layer to maintain horizontal stratification. The preloading of the hanging basket mainly eliminates plastic deformation and measures elastic deformation at the same time. After the bottom form is laid, it is measured before ballasting to obtain the elevation before loading. Then, the pre-prepared preloading sandbags are laid on the formwork and loaded according to the design.

[0050] Pre-stressing precautions: Load in time periods and do not load locally to avoid local instability of the bracket.

[0051] As a further preferred embodiment of the present invention, the installation of the bottom membrane in step B includes the assembly and installation of the outer mold at the cantilever end of the main beam and the assembly and installation of the inner mold. The assembly of the outer mold at the cantilever end of the main beam is carried out using the pier body mold, and the inner mold is assembled using a newly purchased large-block standardized steel mold. Before installation, rust is removed and the mold paint is applied. The molds of the outer mold and the inner mold at the cantilever end of the main beam are both opened with PCV pipes and steel bar pull rods are installed.

[0052] As a further preference of the present invention, the installation of the inclined cables in step C includes the following steps: installing temporary measures on the construction basket, then locking the No. 1 cable and one cable, pouring half of the concrete after completion, performing the second cable, pouring concrete for the second time, prestressing, converting the No. 1 cable and three cables, repeating the above steps to install cables No. 2 to No. N, and after the construction of all the inclined cables is completed, the closing section is constructed, and after the construction of the closing section, constant pressure loading is performed, and the entire bridge is adjusted. After the adjustment of the entire bridge is completed, accessories are installed and anti-corrosion is performed. In the steps, one cable is preloaded to 50%, the template is fine-tuned and fixed, and when half of the concrete is poured, the two cables are preloaded to 100%.

[0053] The cable-stayed cable is composed of an anchoring section + a transition section + a free section + a transition section + an anchoring section, and the steel strand in the HDPE sheath has four layers of protection: (1) a filamentary epoxy coating; (2) anti-corrosion grease; (3) a small PE sheath layer for each steel strand; (4) a double-layer HDPE outer sheath, in which the outer layer is a double-helix colored protective sleeve, and the third and fourth layers are separated. The PE sheath is not subjected to stress, thus extending its service life. The cable installation process is determined according to the main beam construction conditions. When installing the cable-stayed cable, a construction platform, passage and hoisting system must be set up. The construction platform includes a beam end platform, a tower platform, a tower outside hanging basket and a tower top platform. The beam end platform uses a front fulcrum cantilever hanging basket.

[0054] Tower platform: The tower end inclined cable is anchored on the concrete tooth block. Steel plates can be buried in the inner wall of the vertical tower column below the end face of the corresponding cable number tooth block, and a temporary operation platform can be welded, covered with steel springboards or thick templates, and the skirting board prevents the tools from falling. The scaffolding steel pipes are welded to make edge protection railings. Each tower is equipped with 4 valid dry powder fire extinguishers, and flammable debris (gloves, cotton yarn heads) are cleaned every day. Smoking is strictly prohibited in the tower. Hot work must be approved. One person must be assigned to supervise during hot work to ensure that fire prevention measures are in place before work can be carried out. The jacks and tensioning tools used for tensioning can be placed on the steel anchor beam or the concrete transfer layer in the tower.

[0055] Tower hanging basket: After the tower top is capped, the tower top bracket is installed, which provides the hanging point for the tower platform. The tower platform uses a self-lifting high-altitude operation hanging basket, and the operating instructions and inspection report of the hanging basket are also attached.

[0056] Tower top platform: The top platform mainly provides high-altitude lifting points for the platform outside the tower and the platform inside the tower, and provides an operating platform for the winch and the cable-threading machine.

[0057] The installation principle of the cable strand is as follows: When hanging a single cable, the steel strand is pulled from the bridge deck through the tower top drum threading machine to the cable duct pipe outlet outside the tower, and then passed along the inner wall of the HDPE outer sheath circular tube at the tower end to the beam pipe outlet, and then passed back from the bridge deck pipe outlet to the bottom of the beam, and temporarily anchored with clamps. The steel strand is pulled into the hole through an electric hoist in the tower, and temporarily anchored with clamps after reserving sufficient length. Then a single tensioning jack is installed for tensioning and pre-tightening. After tensioning is completed, the next cycle continues. Four cables are installed simultaneously, each one is installed row by row from top to bottom, and one cable in the same row is installed one by one in the order from outside (outside of the bridge deck) to inside (inside of the bridge deck). The equivalent tensioning method is used for single tensioning until the cable hanging work is completed.

[0058] Cable hanging system layout of cable threading machine: The cable threading process is adopted from top to bottom. A cable threading machine is arranged on the top of the tower. The cable threading machine on the top of the tower is used to provide power for threading a single steel strand. The cable threading system is mainly composed of a cable threading machine, connectors, plastic hoses, etc. The cable can be threaded first or while the material is being laid, depending on the site conditions.

[0059] A cable threading machine is arranged on the top of the tower. The length of the pre-stored steel strands in the cable threading machine is calculated according to the tower height and the storage position of the cable drum. The pre-stored steel strands are lowered by the cable threading machine, passed through the steering device under the tower column, led out and connected with the bridge deck steel strands, and then the pre-loaded steel strands are pulled to the top of the tower and passed through the PE pipe until they are anchored.

[0060] The steering device is fixed to the embedded parts on the bridge deck below the side wall of the bridge deck tower and is firmly fixed by welding with angle steel. It only serves to deflect the steel strands and is subjected to small forces, so no force calculation is required.

[0061] When installing the cable strand, it is also necessary to install the tower and beam end anchors. The technical requirements for anchor installation are as follows: (1) The anchor holes at the tensioning end and the fixed end are arranged horizontally in each row of holes. The anchor holes at both ends correspond to each other and there should be no misalignment. The position of the nuts should be adjusted properly. (2) The center line of the anchor is consistent with the center line of the anchor pad; (3) The anchor grouting hole is at the bottom and the exhaust hole is at the top.

[0062] When installing the cable-stayed cable strand, if there is enough space on the bridge deck, the HDPE pipe is welded on the bridge deck, otherwise it is welded on the trestle. Before welding the HDPE pipe, the welding length should be reviewed to avoid the situation where the HDPE pipe is insufficient in length due to thermal expansion and contraction after later operation. At the same time, during welding, the coaxiality, welding temperature, heating time, switching time, welding pressure, cooling and holding time, etc. should be controlled according to the technical briefing requirements to ensure the welding quality. Before hoisting the HDPE sheath pipe, various integral accessories at the beam end and tower end, such as the beam end PE connection device, shock absorber adjustment protective pipe, beam end protective steel pipe, thermoplastic sleeve and tower end PE connection device, shock absorber adjustment protective pipe, etc., should be assembled and fixed according to the drawing position (can be fixed on the clamp), and the steel strand should be tensioned according to the cable force that meets the verticality to make the sleeve straighten and lift to the designed angle to facilitate the next step of hanging the cable.

[0063] The process flow of a single rope hanging is as follows: (1) The steel strand is placed on a cable drum near the tower column; (2) The cable threading machine pulls the fixed-end steel strand from the bridge deck to the PE pipe opening outside the tower; (3) The cable threading machine passes the steel strand from the PE pipe opening to the waterproof cover opening; (4) The cable is switched outside the tower; (5) After pulling inside the tower to meet the tensioning length, the clamp is temporarily anchored; (6) The steel strand at the tower end is pulled into the tower; (7) After the bottom of the beam is reversed and the clamp is temporarily anchored, the tower end is notified to tension; (8) The tensioning jack is installed inside the tower and tension is performed according to the monitoring instructions; (9) The next steel strand is passed through in a cycle; For the single cable threading sequence, the cables are hung simultaneously in the middle and side spans and upstream and downstream of each pair of cable stays; to ensure that the steel strands are not twisted, the following principles must be followed when threading each cable bundle: Install row by row from top to bottom, and install the same row from outside (outside of the bridge deck) to inside (inside of the bridge deck); the anchor holes at the tensioning end and the fixed end must correspond one to one; use the equivalent tensioning method to tension a single steel strand and hang the cable according to the design requirements and monitoring instructions.

[0064] In order to make the tension of each steel strand in each cable uniform, the equal tensioning method is adopted, that is, the tension of each steel strand is monitored by the sensor reading, and the actual cable force measured by the sensor is fed back to the intelligent control box, and equal tension is achieved by controlling the control box.

[0065] In order to reduce the influence of verticality, the sensor is installed on the first steel strand of the second row. The installation order is: conical support, plum blossom support - sensor body - single-hole working anchor and tool clip. Therefore, the first row sets the reference cable tension, selects the conversion oil pressure, and then adjusts to the over-tension gear for tensioning. After the tension reaches the set reference cable tension, it will automatically maintain the pressure; until the sensor is installed, it is adjusted back to the equal-tension gear for automatic tensioning.

[0066] Install a pressure sensor on the first steel strand of the second row at the tensioning end and tension it to the reference tensioning cable force. When the next steel strand is about to be tensioned, the cable force of the installed steel strand will change due to structural deformation or temperature changes, and the sensor will also change accordingly. According to this change value, adjust the tensioning oil pressure of the steel strand to make it the same as the existing cable force of the steel strand with the sensor installed, and then anchor it. Similarly, the tension of each steel strand will be controlled according to the change of the pressure sensor, that is, the tension of each steel strand will be the same as the existing tension of the steel strand with the sensor installed. The purpose of over-tensioning the first row of steel strands of the anchor is to straighten the PE pipe and try to eliminate the influence of the deadweight of the PE pipe on the tension of the steel strand installed on the sensor. When the last steel strand is tensioned, the tension of the first row of steel strands is supplemented according to the cable force value on the display. If the cable force value is greater than the average cable force of a single strand, it is released to the average value; if it is less than the average cable force value of a single strand, the cable force is supplemented to the average cable force, and finally the sensor component is removed.

[0067] There are three main cable tension adjustments, namely the second and third tensioning during the construction process and the cable tension adjustment of the entire bridge.

[0068] If some cable numbers do not meet the requirements of overall tensioning due to space or other reasons, they need to be adjusted using the single-wire tensioning method. The cable force adjustment process is the same as that of single-wire tensioning.

[0069] After the cable is completed, the cable tightening and shock absorber installation work can be carried out without affecting the cable force monitoring.

[0070] Finally, the cable-stayed cables need to be protected, including corrosion protection of the cable body, corrosion protection inside the anchor head, and corrosion protection of the anchor head end face, clips, and exposed steel strands.

[0071] As a further preference of the present invention, the installation of the steel bars and prestressed pipes is specifically that before tying the bottom plate steel bars, the specific positions of the steel bars shall be marked on the pre-installed bottom formwork according to the dimensions of the design drawings, and then the steel bars shall be tied. The steel bars shall be processed into semi-finished products in batches in the steel bar processing room and transported to the site for installation and forming. The connection of the steel bars must ensure the welding quality, and the number of steel bars connected in the same section should not exceed 50%.

[0072] As a further preference of the present invention, the installation of prestressed pipes in the installation of steel bars and prestressed pipes includes pipe installation and measures for resolving conflicts between pipes and steel bars. When installing the pipes, the prestressed pipes of the beams are all made of plastic corrugated pipes with holes and vacuum grouting technology. The installation of the prestressed pipes of the main beams is carried out simultaneously with the steel bars, and the corrugated pipes are fixed by U-shaped steel bar clamps. If the main bars conflict with the steel bundle corrugated pipes due to special reasons, the measures for resolving the steel bar conflicts are specifically as follows: according to the markings in the construction drawings, if the prestressed anchorage interferes with the steel bars, the steel bars are moved to both sides of the prestressed sleeves; if the prestressed steel bars conflict with the steel, the main bars can be fine-tuned, and if they need to be cut off, equal strength reinforcement measures need to be taken.

[0073] As a further preference of the present invention, the concrete pouring sequence is to first symmetrically pour the main longitudinal ribs on both sides and then pour from the bridge span direction to the main pier direction. The pouring is carried out in horizontal layers and oblique sections according to the cross-section of the beam. The front and rear pouring distance between the upper and lower layers is not less than 1.5m, and the pouring thickness of each layer does not exceed 30cm. During the concrete pouring process, attention is paid to making the concrete enter evenly to avoid a large amount of concentrated entry into the mold. An experienced concrete worker is assigned to be responsible for vibration. The vibration is carried out using an inserted vibrator with a moving spacing not exceeding 1.5 times its effective radius. A spacing of 5 to 10cm should be maintained with the side mold, and the lower layer of concrete should be inserted about 5 to 10cm. All parts are vibrated and compacted. The sign of compaction is that the concrete stops sinking, no more bubbles appear, the surface is flat, and there is slurry. After each vibration is completed, the vibrator is slowly pulled out to avoid collision with the formwork, steel bars, prestressed pipes and other embedded parts. Concrete maintenance is also required after pouring.

[0074] As a further preferred embodiment of the present invention, the prestressed construction in the beam body includes g1, processing and installation of prestressed steel bundles; e2, prestressed tensioning of the main beam; and e3, grouting and anchor sealing of the prestressed ducts.

[0075] When constructing prestress in the beam, the prestressing materials and equipment must be prepared first, including the preparation of steel strands, anchors, corrugated pipes, and tensioning equipment. Before the tensioning construction, detailed instructions, static calculations of tensioning stress and elongation should be submitted to the supervision engineer for approval. In order to verify whether the implemented prestressing meets the design requirements, it is necessary to conduct a prestressing channel friction test on the main beam of the bridge during the cantilever construction process. Through the test, the actual friction data is obtained to guide the actual prestressing tensioning construction. Before carrying out prestressed construction, you also need to understand the prestressing tensioning sequence, tensioning construction process, tensioning procedures, and the requirements for cleaning anchors and anchor pads.

[0076] The prestressing sequence is to tension the longitudinal prestressing tendons first, and then the transverse plate prestressing tendons. The top plate transverse prestressing needs to be tensioned one segment later.

[0077] The requirements for tensioning include: (1) Longitudinal prestressed tendons (large) of longitudinal beams are tensioned symmetrically upstream and downstream; (2) Longitudinal prestressed tendons (small tendons) of plates are tensioned symmetrically from both sides to the middle and upstream and downstream; (3) Prestressed tendons of transverse diaphragms are tensioned at both ends; (4) Transverse prestressed tendons of top plates (lagging one section) are tensioned symmetrically upstream and downstream in the direction of 0#~N# blocks.

[0078] The tensioning construction process is as follows: The construction procedure for tensioning the longitudinal steel strand bundle: clean the anchors and anchor pads, cut off the excess corrugated pipes → remove rust from the steel strands, cut the materials, bundle, make bundle heads, and thread the bundles → cut off the excess steel strands, install working anchors, jacks and tool anchors → proceed after the concrete of the beam section reaches more than 90% of the design strength and the age is not less than 5d → cut off the excess steel strands after the tensioning is completed and qualified → seal the anchors and grouting.

[0079] The prestressing tendon tensioning procedure is: 0 → initial stress → σcon (holding load for 5 minutes) → anchoring (measuring elongation); The requirements for cleaning anchors and anchor pads are as follows: clean the cement slurry and concrete on the anchors and anchor pads; clear the grouting holes on the anchor pads to ensure smooth grouting channels; handle the misalignment at the connection between the anchor pads and the corrugated pipes to make the connection smooth; remove the excess corrugated pipes in the anchor pads. Check whether the anchor pads are correctly placed and whether they are perpendicular to the hole. If there are any problems, handle them first. Do not use anchors and clips that cannot be cleaned of rust or are damaged.

[0080] After understanding the above situation, the preparatory work for tensioning is carried out. The preparatory work for tensioning includes: inspection work before tensioning, cutting off excess steel hinge wires, installing working anchors and clips, installing jacks and tool anchors, and tool clips.

[0081] After finishing the tensioning preparation work, prestressing is carried out. At the beginning of prestressing, check that the oil pipe connection is reliable and correct, start the oil pump, slightly tighten the steel hinge wire, and then adjust the position of the jack to make its center basically consistent with the axis of the hole to ensure that the steel hinge wire can stretch freely and reduce friction. At the same time, adjust the tool clip to clamp the steel hinge wire to ensure that each steel hinge wire is evenly stressed. Then, the main oil cylinders of the jacks are slowly filled with oil at both ends to make the elongation of both ends basically consistent. After the initial tension force (0.1σcon) is loaded, the oil supply is stopped. After checking that the clamp is in good condition, a line is drawn to mark it. Continue to add oil to the jack until the controlled tension is reached. The tension value is mainly determined by the reading of the oil pressure gauge, and is checked by the elongation value of the prestressed steel strand. The retraction of the anchor at each end is controlled within 6mm; After the oil pressure reaches the tensioning tonnage, close the main oil cylinder oil circuit and maintain it for 5 minutes. Measure the elongation of the steel strand and check it. After maintaining it for 5 minutes, if the oil pressure drops slightly, add oil to the oil pressure value of the designed tonnage, the jack returns oil, the clamp automatically locks, and the tensioning of the bundle is completed. Make records in time. The total number of broken wires and slipped wires in the whole beam shall not exceed 0.5% of the total number of steel wires, and no more than one broken wire in a bundle shall be broken, and they shall not be on the same side; When the steel strand is too long to be tensioned in place at one time, multiple tensioning cycles are required. The operating methods and steps for multiple tensioning are the same as those described above, except that the anchor tension (stress) of the previous cycle is used as the initial value of this cycle, and this cycle is repeated until the final controlled tension is reached.

[0082] The measurement method of the elongation of the hinged wire bundle is as follows: the corresponding extension of the jack cylinder is measured under the corresponding tensioning force, and the difference between the extension of the jack cylinder under the initial tensioning force and the final tensioning force in each tensioning cycle is used as the elongation of the steel hinged wire bundle in this tensioning cycle. The sum of the elongations of each tensioning cycle is the elongation of the steel wire bundle between the initial tensioning force and the controlled tensioning force.

[0083] The calculation formula of the actual elongation of the steel strand △L is: △L=∑△L1+△L2. In the formula, △L1 is the measured elongation between the initial tension force and the controlled tension force; △L2 is the elongation between zero and the initial tension force, and its value is calculated from the elongation between 0.1σcon and 0.2σcon.

[0084] The tensioning of the stranded wire bundle adopts the dual control method of tensioning force and elongation value, that is, after the tensioning force reaches the design requirement, if the error between the actual elongation value and the theoretical value is between -6% and +6%, it means that the tensioning of this bundle of steel strands is qualified. Otherwise, although the tensioning force has reached the design requirement, the error between the actual elongation value and the theoretical elongation value exceeds the standard, the construction is suspended and the tensioning is continued after the cause is analyzed and dealt with.

[0085] The reasons for the excessive elongation are analyzed from the following aspects: the reliability of the tensioning equipment, i.e. the accuracy of the tensioning force; the accuracy of the friction resistance and deviation coefficient of the corrugated pipe channel; the deviation between the calculated value and the actual value of the elastic modulus of the steel hinge wire; the reasons for the measurement and calculation of the elongation, such as not considering the elongation value of the steel hinge wire in the jack, etc. If everything is normal, seal the end of the anchor and grout as soon as possible.

[0086] As a further preferred embodiment of the present invention, the lowering of the hanging basket in step f and then the walking anchoring and template lifting and installation specifically include the following steps: f1, removing the inner mold chamfer oblique support, rotating the chamfer template to vertical, and installing the inner mold arch frame lifting system boom; f2, lowering the inner mold arch frame to the bottom, removing the inner mold support rod, rotating the inner mold to the arch frame template, and the outer mold horizontally moving outward; f3, the thrust jack is lowered, the thrust piece is loosened from the beam body, and the rear anchor system is removed; f4, the middle anchor boom is lowered, and the tail balance jack is synchronously lifted until the C-hook roller falls into the slide slot and the tail reaction wheel is rotated and fixed in place; f5, the middle anchor system is removed, the hanging basket walking traction system and reaction device are installed, the tail balance jack is lowered, and the preparation work for the hanging basket to walk is completed; f6, before the hanging basket walks, all anchor rod groups are removed, and the height of all side templates after falling is fully checked The degree of the hanging basket is to avoid the conflict between the component and the concrete boundary of the beam body. The side and middle span hanging baskets move symmetrically. The track plate is padded with fine sand to make it dense and flat. The hanging basket moves steadily and straightly. The oil top tensioning times and walking distances on both sides are consistent. The walking error on both sides of the hanging basket is kept within 2cm. The inner edge line of the hanging basket bottom plate is consistent with the inner edge line of the bottom surface of the beam body concrete to ensure that the hanging basket does not deviate. Before the hanging basket moves to the last stroke, observe the position of the anchor group eyelet according to the two symmetrical points on the upstream and downstream sides. After walking in place, ensure that the position corresponds accurately; f7, the walking traction system and the reaction device are removed, the middle anchor system is installed, the tail balance jack is lifted to the bottom of the beam, and the reaction wheel is loosened and rotated to a horizontal state; f8, the middle anchor boom is lifted, and the tail balance jack is lowered synchronously. When the thrust seat contacts the bottom of the beam, the hanging basket is lifted and the rear anchor system is installed; f9, the thrust jack is lifted and the thrust piece is fixed in place.

[0087] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. First of all, in this method, the hanging basket is installed by hoisting after assembly, and the corresponding assembly site is selected according to the position of the pier. This is not only efficient, but also has small errors and good stability after hoisting.

[0088] 2. When pouring concrete, concrete with good fluidity, workability, water retention, cohesion and bulk density is used. After the concrete is poured, its maintenance is carried out by covering the surface with geotextile and sprinkling water to ensure that the concrete surface is moist and not directly exposed to the sun and rain. This effectively solves the problems of uneven concrete pouring, loss of prestressed tensioning stress, and incomplete grouting during the construction stage.

[0089] 3. The correction mechanism can ensure that the moving trajectory of the hanging basket is consistent with the axis of the beam body to avoid deviation or shaking. In summary, this solution has more advantages than the existing technology.

[0090] 4. A hanging basket monitoring system is also set up at the hanging basket. The system is an interactive information management platform developed for the hanging basket that integrates collection monitoring, recording, analysis, diagnosis, early warning and statistics. It not only meets the requirements of the national standard GB / T 28264-2017 Crane hanging basket monitoring system, but also incorporates a variety of crane monitoring, maintenance, management and other practical functions, which can effectively control the entire hanging basket construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 It is a process flow chart of the present invention.

[0092] Figure 2 It is a flow chart of the hanging basket walking of the present invention.

[0093] Figure 3 This is a diagram of the prestressing sequence during prestressing construction of the present invention.

[0094] Figure 4 This is a process flow chart for installing the stay cable of the present invention. DETAILED DESCRIPTION

[0096] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0097] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0098] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0099] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0100] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0101] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Specific embodiment 1: A highly efficient construction method for symmetrical suspended pouring of the main beam of a cable-stayed bridge based on a front-support cable hanging basket, which adopts a front-support hanging basket symmetrical suspended pouring method, including the following steps: A, hanging basket installation; B, bottom membrane installation; C, inclined cable installation and tensioning; D, steel bar and prestressed pipe installation; E, end membrane installation; F, concrete pouring; G, prestressing construction in the beam body; H, lowering the hanging basket and then carrying out the hanging basket walking anchoring and template lifting installation, and the construction is completed after completion; The hanging basket is installed by hoisting after assembly, and the corresponding assembly site is selected according to the location of the bridge pier; The concrete used in concrete pouring is a concrete with good fluidity, workability, water retention, cohesion and bulk density. The concrete needs to be poured evenly into the mold and then vibrated to make it dense. Prestressing requires multiple tensioning cycles. A deviation correction mechanism is provided at the rear of the hanging basket.

[0103] Firstly, in this method, the hanging basket is installed by hoisting after assembly, and the corresponding assembly site is selected according to the position of the bridge pier, which is not only efficient, but also has small errors and good stability after hoisting. Then, when pouring concrete, concrete with good fluidity, workability, water retention, cohesion and bulk density is used. After the concrete is poured, the surface is covered with geotextile and watered to ensure that the concrete surface is moist and not directly exposed to the sun and rain. The raw materials of the concrete are as follows: 478 parts of cement, 78 parts of fly ash, 675 parts of sand, 1055 parts of crushed stone, 150 parts of water, and 7.2 parts of admixture. The admixture is a polycarboxylic acid high-performance water reducer produced by Sichuan Sanhe Concrete Admixture Co., Ltd. By selecting a suitable water reducer or adjusting the dosage of the water reducer, the initial setting time of the concrete mixture can be reasonably extended to meet the construction time of on-site concrete pouring. The compatibility test of the water reducer and cement is carried out. And by adjusting the composition of the water-reducing agent, the effective initial setting time of the concrete is ensured. The polycarboxylic acid high-efficiency water-reducing agent with stable performance and high water-reducing rate is preferably used, which can effectively reduce the amount of cement used per cubic meter of concrete, thereby reducing the hydration heat temperature rise of the concrete. The crushed stone is 5~25mm continuously graded stone, and the mud content in the crushed stone is ≤1.0%. The concrete made of the above raw materials has good fluidity, workability, water retention, cohesion and bulk density, so it can be well spread evenly, and vibration compaction is also carried out during pouring, which effectively solves the problems of uneven concrete pouring, prestressed tension stress loss, and incomplete grouting during the construction stage. Finally, a correction mechanism is set on both sides of the rear part of the hanging basket, and the correction mechanism can ensure that the moving trajectory of the hanging basket is consistent with the axis of the beam body to avoid deviation or shaking. In summary, this solution has more advantages than the existing technology. Specific embodiment 2: This embodiment further illustrates step A on the basis of specific embodiment 1. The hanging basket in the hanging basket installation in step A includes a main longitudinal beam, a C-shaped hook, a front cross beam, a middle cross beam, a rear cross beam, a middle anchor rod, a rear anchor rod, a walking reverse roller, a jacking mechanism, a thrust mechanism, a template system and a traction system. The front cross beam, the middle cross beam and the rear cross beam are respectively arranged at the front, middle and rear of the inner side of the main longitudinal beam. The lower part of the C-shaped hook is connected to the middle part of the outer side of the main longitudinal beam. The lower end of the middle anchor rod is connected to the middle cross beam. The main longitudinal beam is connected to the rear end of the main longitudinal beam, the lower end of the rear anchor rod is connected to the rear cross beam, the walking counter roller is rotatably arranged at the tail of the main longitudinal beam, the formwork system is arranged on the inner side of the main longitudinal beam, the jacking mechanism includes an inner formwork frame lifting mechanism, a middle anchor rod lifting mechanism and a tail balancing jack, the top of the inner formwork frame lifting mechanism is connected to the inner formwork arch frame of the formwork system, the top surface of the middle anchor rod lifting mechanism is connected to the middle anchor rod, the tail balancing jack is arranged on the top surface of the rear of the main longitudinal beam, and the thrust mechanism is arranged at the rear of the main longitudinal beam.

[0105] The main longitudinal beam of the hanging basket is divided into three sections, namely the arc head, the main longitudinal beam section 1 and the main longitudinal beam section 2. The arc head is installed with the tension distribution beam for tensioning the inclined cable. The C-type hook is a box-shaped section. The C-type hook fulcrum and the track sliding are used at the top to complete the movement of the hanging basket. When the hanging basket is lowered as a whole, the C-type hook falls on the channel steel track of the bridge deck, and the tail reaction wheel rotates in place and is fixed. The tail balance jack is lifted synchronously. Through the temporary reaction device at the outer end of the cast beam section, the reaction wheel at the rear of the hanging basket is used, and the step compound jack is used on the front to realize the movement of the hanging basket. The inner mold support system of the hanging basket adopts the form of an arch frame. The arch frame supports the template through steel pipes, which can realize the overall lowering and raising of the inner mold. A basket monitoring system is also set up at the basket. This system is an interactive information management platform developed for the basket that integrates collection monitoring, recording, analysis, diagnosis, early warning, and statistics. It not only meets the requirements of the national standard GB / T28264-2017 crane basket monitoring system, but also incorporates a variety of crane monitoring, maintenance, management and other practical functions. It is a monitoring system that integrates equipment management and personnel behavior control, and truly implements safety monitoring measures. The system includes a remote data center, a data monitoring system and a video monitoring system. The data monitoring system is mainly composed of a signal collector, which is provided with a zigbee module. The power supply of the signal collector is provided by a UPS power supply. The terminals connected to the signal collector include a wind speed sensor, a lifting encoder, an inclination sensor, a temperature and humidity sensor, a force sensor, and a stress sensor. The power supply of the signal collector is provided by a UPS power supply. An annular hollow force sensor is installed on multiple anchors at the anchors and the middle cross beam of the hanging basket. The signal collector collects the anchoring force of the anchors on both sides and reflects it to the host in real time to measure the force difference on both sides of the hanging basket to prevent accidents caused by uneven force on site. Stress sensors are installed at the beam, rear anchor and other positions. The specific position can be based on the requirements of Party A to install stress sensors at the corresponding positions to monitor the overall stress of the hanging basket in real time. The inclination sensor is installed at the corresponding position by welding to monitor the dual-axis deflection of the point. The inclination sensor signal is centrally transmitted to the host for display through the collector, and an infrared distance sensor is installed at the walking mechanism position by welding to the corresponding position to monitor the forward movement of the hanging basket. The sensor transmits the signal to the host through the collector and displays it, and sets a limit on the host side. When the hanging basket exceeds the limit during operation, the host alarms. Temperature and humidity sensors are arranged on the steel mesh to monitor the temperature of concrete pouring and send signals to the temperature and humidity monitoring system. If the temperature and humidity data of a certain concrete is abnormal, the upper computer software will automatically start the alarm device and notify the relevant technical personnel to handle it. The hanging basket monitoring system collects data through the signal acquisition module, and the human-machine interface performs statistical conversion, and stores, records and displays the equipment operation working time, cumulative working time and work cycle data; The video surveillance system consists of a video display, a hard disk recorder and a camera, and is connected through Ethernet or 4G network. The cameras of the video surveillance system include ball cameras and gun cameras, both of which have infrared functions. The ball camera is a controllable ball camera that conducts video surveillance of the surrounding environment of the hanging basket, while the gun camera monitors specific parts of the hanging basket. The cameras are all set up at the hanging basket site, and the video display and hard disk recorder are arranged next to Party A's electrical control cabinet; because there is a remote data center, the client can access the data through a browser or mobile phone APP, and the remote terminal can obtain field-level data services to realize the query of the working status of the on-site equipment, which can easily increase the number of simultaneous accesses and expand the network.

[0106] The advantages of the hanging basket monitoring system are as follows: (1) Simple structure: The human-machine interface wireless host computer effectively reduces investment and maintenance costs; (2) The entire system uses the signal acquisition box as the main control element and mechanical limit protection to achieve control, making the entire system highly reliable; (3) The entire system can meet the client's inspection requirements and detect the sensor signals at each point in real time to achieve safe construction of the project; (4) The entire system adopts wireless communication mode, which has the advantages of simple installation, fast disassembly, compact structure, and interoperability; (5) Data and video information can be sent to the background through DTU or the Internet, and can be viewed remotely in real time and analyzed in the background to determine the correctness of the operation; (6) The system can have a built-in SMS module, and when there is a major violation of regulations, SMS notifications can be sent to relevant supervisory posts in a timely manner.

[0107] After the above system is set up, the accuracy of the hanging basket installation can be guaranteed, the posture can be adjusted in time during movement, and the overall stress and anchoring conditions of the hanging basket can be monitored in real time. Specific embodiment 3: This embodiment further illustrates step A on the basis of specific embodiment 1. In step A, the installation of the hanging basket includes the installation of the hanging basket at the bridge pier near the bank of the river and the installation of the hanging basket at the bridge pier in the middle of the river. The installation of the hanging basket at the bridge pier near the bank of the river includes land assembly and hoisting, and the installation of the hanging basket at the bridge pier in the middle of the river includes assembly and hoisting on the long-mileage side and assembly and hoisting on the short-mileage side. The assembly in the long-mileage side assembly and hoisting is carried out on the pier, and the assembly in the short-mileage side assembly and hoisting is carried out on the ship.

[0109] When assembling on board, as the number of hanging basket components on board increases, the ship will tilt. When the height difference of the tilt is greater than 10cm, add counterweight in time.

[0110] The boat is docked on the river bank upstream of the bridge pier. The assembly steps are as follows: Step 1: Assemble the hanging basket and install the tire frame.

[0111] The position of the main longitudinal beam of the hanging basket is laid out in the cabin of the sand dredging ship, and the assembly frame is installed. After the frame is installed, the outline of the main longitudinal beam is laid out on the frame, and at the same time, the ship obstacles within the assembly range of the hanging basket are checked and cleared.

[0112] Step 2: Lifting of main longitudinal beam A.

[0113] After the main longitudinal beam outline is laid out and the obstacles on the ship are cleared, the main longitudinal beam A is hoisted. After the single-side main longitudinal beam A is hoisted, four 3t chain hoists are used to fix the main longitudinal beam A on the sand dredging ship to prevent the main longitudinal beam A from capsizing.

[0114] Step 3: Assemble the arc head.

[0115] After the main longitudinal beam A is hoisted and fixed, assemble the arc head. The arc head and the connecting part of the main longitudinal beam A are connected with the matching high-strength bolts. The bolts are fully inserted and tightened manually.

[0116] Step 4: Assemble the front crossbeam.

[0117] After the arc-shaped head is assembled, assemble the front crossbeam. The front crossbeam is divided into three sections and is assembled in sequence from one side to the other side to facilitate the adjustment and alignment of the bolt eyes of the connecting part. The bolts are fully inserted and tightened manually.

[0118] Step 5: Assemble the middle cross beam.

[0119] After the front crossbeam is assembled, assemble the middle crossbeam. The assembly sequence and bolt connection requirements are the same as the front crossbeam.

[0120] Step 6: Assemble the main longitudinal beam B and the rear cross beam.

[0121] After the middle cross beam is assembled, the main longitudinal beam B is hoisted. After the main longitudinal beam B is hoisted, the rear cross beam and its connecting beam are assembled. After the rear cross beam and its connecting beam are assembled, the bolts of each connection are tightened to the design requirements and checked with a torque wrench. The control torque is 864N·m.

[0122] Step 7: Install other components of the hanging basket.

[0123] After the bolts of the connecting parts of the main components of the hanging basket are tightened and checked, install other components such as the inner mold arch frame, formwork support, working platform, etc. of the hanging basket.

[0124] The torque method used in the construction of high-strength bolts during assembly is divided into two tightening stages: initial tightening and final tightening. The initial tightening torque is 30%-50% of the final tightening torque, and the bolts are tightened with the final torque. If the plate layers are thicker and there are more plate stacks, the initially tightened plate layers may not be sufficiently close together.

[0125] The high-strength bolts on a joint should be installed from the middle of the bolt group and tightened one by one. The final tightening should be started from the middle of the bolt group and extended to the surrounding areas to tighten one by one. Each tightening should be marked with different colors of paint to prevent missing tightening. If the joint is connected by high-strength bolts and electric welding, whether to tighten first or weld first should be done in the order specified in the design requirements. If there is no design requirement, the construction process sequence is tightened first and then welded (i.e. bolted first and then welded). The high-strength bolts are finally tightened first and then the welds are welded. The tightening sequence of high-strength bolts is from the part with large rigidity to the unconstrained free end, and from the middle to the surrounding areas in the same node to make the plates fit tightly.

[0126] The precautions for high-strength bolt construction are as follows: 1) The direction of bolt penetration shall be based on the convenience of construction, and each node shall be neat and consistent; 2) Nuts and washers have direction requirements, and bolts and nuts are marked with grades and manufacturers; 3) Due to the narrow space, the high-strength bolt wrench is not suitable for operation. It can be installed by raising the sleeve or using a manual wrench; 4) If the high-strength bolts are over-tightened, they should be replaced and discarded, and they should not be reused; 5) Gas cutting is not allowed for misaligned holes or leaky holes during installation; 6) Stop working when the temperature is below -10°C; stop working when the friction surface is wet or exposed to rain or snow; 7) High-strength bolts should be kept in factory condition as much as possible during packaging, transportation and use; 8) The torque wrench must be calibrated before construction. When tightening, the large hexagonal bolts should be tightened according to the construction torque, and the torsion shear bolts should be tightened with a special electric wrench; 9) It is strictly forbidden to throw bolts, nuts and washers randomly during high-altitude construction to avoid falling and injuring people.

[0127] After the basket is assembled, it needs to be transported on water. After the basket is assembled on the ship, the center of gravity of the basket is located at about 1 / 4 of the ship contact surface, and there is a certain degree of eccentricity. Before transportation, sandbags are used to counterweight the assembled ship. The stacking height of the sandbags during the counterweight process does not exceed 1.2m. Then tie another transport balance boat to the other side of the assembled ship.

[0128] There is a certain amount of partial load in the hanging basket during transportation. Sandbags are used to counterweight the assembled ship before transportation. F1*L1+F3*L3=F2*L2. The sandbag stacking height can be calculated by the above formula. The sandbags are fixed with anti-fall nets, and a threaded steel bar is welded every one meter on the edge of the ship as a guardrail.

[0129] Before starting transportation, slowly drive the boat to deep water and observe the posture of the hull. If the transport ship tilts too much, drive back to the shore in time to re-fix the balancing boat to ensure that the hull is stable during transportation, and then drive the boat to the designated position for lifting the hanging basket.

[0130] After the boat is driven to the designated position and fixed, the continuous jack and lifting steel strand are installed, and each steel strand is pre-tightened by using a 25T hydraulic single pumping jack. After the pre-tightening is completed, the stroke of 4 jacks is debugged. Before the basket is lifted, the temporary passage and temporary anchoring device between the basket and the hull platform are released. When the basket is lifted, the basket is first lifted 10cm away from the platform and temporarily lifted to allow the basket to automatically balance vertically under the action of its own weight. At the same time, the surrounding conditions of the basket are checked. After the basket automatically balances vertically and the surrounding conditions are checked, the basket is lifted continuously normally. During the whole process of the basket lifting, 4 people are arranged on the main beam to observe the working status of the continuous jacks at the upstream and downstream basket hanging points, and another 4 people are arranged on board to observe the lifting balance of the basket. When the basket is lifted to the anchor installation height range, the continuous jack lifting is stopped, the basket's own anchor lifting system is installed, and the basket is lifted into place using the basket's own anchor lifting system. After the basket is lifted into place, the continuous jack lifting system and lifting bracket are removed, and the remaining anchor system of the basket is installed.

[0131] The specific steps of the above hanging basket lifting process are as follows: Step 1: Dock the transport ship at the designated location and anchor it stably.

[0132] When the transport ship is docked, use the 1# lifting hole to lower the plumb line for positioning, and stop the ship and drop anchor after the 1# lifting hole is aligned with the lifting hole of the hanging basket.

[0133] Step 2: After the transport ship is fixed, install the continuous jacks and lift the steel strands, and use the hydraulic single pump to pre-tighten each steel strand. After pre-tightening, debug the stroke of the four jacks.

[0134] Step 3: Before lifting the hanging basket, remove the temporary passage and temporary anchoring device between the hanging basket and the platform.

[0135] When lifting the hanging basket, first lift the hanging basket 10cm away from the platform and temporarily lift it to allow the hanging basket to automatically balance and stand upright under its own weight. At the same time, check the surrounding conditions of the hanging basket. After the hanging basket automatically balances and stands upright and the surrounding conditions are checked, disassemble the transport ship and withdraw from the installation position. Use one of the ships to transport the main longitudinal beam crane platform to the installation position and install it using a tower crane. Step 4: After the main longitudinal beam hanging platform is installed in place, lift the hanging basket normally and continuously.

[0136] During the whole process of the basket lifting, 4 people were arranged on the main beam to observe the working status of the continuous jacks at the upstream and downstream basket lifting points. Another 4 people were arranged on board to observe the lifting balance of the basket.

[0137] Step 5: When the basket is lifted to within the anchor installation height range, stop continuous jack lifting.

[0138] Install the hanging basket's own anchor rod lifting system, and use the hanging basket's own anchor rod lifting system to lift the hanging basket into place.

[0139] Step 6: After the hanging basket is lifted into place, remove the continuous jack lifting system and lifting bracket, and install the remaining anchoring system of the hanging basket.

[0140] Finally, in order to ensure construction safety, the raw material steel bars are used to pile up in different areas for preloading of the hanging basket, and the stress condition after the hanging basket is poured into concrete is simulated to observe the settlement and deformation. The construction steps of the hanging basket preloading are: preloading preparation (conduct technical explanation, arrange construction personnel, arrange mechanical equipment, prepare loading preloading materials → fix the hanging basket in place → inspect and accept the hanging basket → mark the observation points → load in stages → observe and record → let it stand still and observe and record → collate and analyze data → report on preloading test results → adjust the bottom formwork of the hanging basket.

[0141] The preloading is carried out in stages, with 50% and 110% loading. After each level of loading, the settlement is measured after 3 hours of static loading and records are kept. The preloading should be uniform during preloading to avoid eccentric compression of the bracket causing instability of the bracket. The loading sequence is consistent with the construction sequence of cast-in-place concrete. Concrete construction is continuously poured in longitudinal sections and horizontal layers. According to the loading sequence of the main longitudinal beam, transverse partition, last top plate and wing plate. When preloading, it should start from the bottom and expand and rise layer by layer to maintain horizontal stratification. The preloading of the hanging basket mainly eliminates plastic deformation and measures elastic deformation at the same time. After the bottom form is laid, it is measured before ballasting to obtain the elevation before loading. Then, the pre-prepared preloading sandbags are laid on the formwork and loaded according to the design.

[0142] Pre-stressing precautions: Load in time periods and do not load locally to avoid local instability of the bracket. Specific embodiment 4: This embodiment further explains step B on the basis of specific embodiment 1. In step B, the installation of the bottom membrane includes assembling and installing the outer mold at the cantilever end of the main beam and assembling and installing the inner mold. The outer mold at the cantilever end of the main beam is assembled by using the pier body mold, and the inner mold is assembled by using a newly purchased large-block standardized steel mold. Before installation, rust is removed and mold paint is applied. Holes are opened in the molds of the outer mold and the inner mold at the cantilever end of the main beam to penetrate PCV pipes and set steel bar pull rods. Specific embodiment 5: This embodiment further illustrates step C on the basis of specific embodiment 1, wherein the installation of the inclined-stayed cable in step C comprises the following steps: installing temporary measures on the construction hanging basket, then padlocking the No. 1 cable and one cable, pouring half of the concrete after completion, performing the second cable, pouring concrete for the second time, prestressing, converting the No. 1 cable and three cables, repeating the above steps to install cables No. 2 to No. N, and after the construction of all the inclined-stayed cables is completed, the closing section is constructed, constant pressure loading is performed after the construction of the closing section, and the entire bridge is adjusted. After the adjustment of the entire bridge is completed, accessories are installed and anti-corrosion is performed, and in the steps, one cable is preloaded to 50%, the template is fine-tuned and fixed, and when half of the concrete is poured, the two cables are preloaded to 100%.

[0145] The cable-stayed cable is composed of an anchoring section + a transition section + a free section + a transition section + an anchoring section, and the steel strand in the HDPE sheath has four layers of protection: (1) a filamentary epoxy coating; (2) anti-corrosion grease; (3) a small PE sheath layer for each steel strand; (4) a double-layer HDPE outer sheath, in which the outer layer is a double-helix colored protective sleeve, and the third and fourth layers are separated. The PE sheath is not subjected to stress, thus extending its service life. The cable installation process is determined according to the main beam construction conditions. When installing the cable-stayed cable, a construction platform, passage and hoisting system must be set up. The construction platform includes a beam end platform, a tower platform, a tower outside hanging basket and a tower top platform. The beam end platform uses a front fulcrum cantilever hanging basket.

[0146] Tower platform: The tower end inclined cable is anchored on the concrete tooth block. Steel plates can be buried in the inner wall of the vertical tower column below the end face of the corresponding cable number tooth block, and a temporary operation platform can be welded, covered with steel springboards or thick templates, and the skirting board prevents the tools from falling. The scaffolding steel pipes are welded to make edge protection railings. Each tower is equipped with 4 valid dry powder fire extinguishers, and flammable debris (gloves, cotton yarn heads) are cleaned every day. Smoking is strictly prohibited in the tower. Hot work must be approved. One person must be assigned to supervise during hot work to ensure that fire prevention measures are in place before work can be carried out. The jacks and tensioning tools used for tensioning can be placed on the steel anchor beam or the concrete transfer layer in the tower.

[0147] Tower hanging basket: After the tower top is capped, the tower top bracket is installed, which provides the hanging point for the tower platform. The tower platform uses a self-lifting high-altitude operation hanging basket, and the operating instructions and inspection report of the hanging basket are also attached.

[0148] Tower top platform: The top platform mainly provides high-altitude lifting points for the platform outside the tower and the platform inside the tower, and provides an operating platform for the winch and the cable-threading machine.

[0149] The installation principle of the cable strand is as follows: When hanging a single cable, the steel strand is pulled from the bridge deck through the tower top drum threading machine to the cable duct pipe outlet outside the tower, and then passed along the inner wall of the HDPE outer sheath circular tube at the tower end to the beam pipe outlet, and then passed back from the bridge deck pipe outlet to the bottom of the beam, and temporarily anchored with clamps. The steel strand is pulled into the hole through an electric hoist in the tower, and temporarily anchored with clamps after reserving sufficient length. Then a single tensioning jack is installed for tensioning and pre-tightening. After tensioning is completed, the next cycle continues. Four cables are installed simultaneously, each one is installed row by row from top to bottom, and one cable in the same row is installed one by one in the order from outside (outside of the bridge deck) to inside (inside of the bridge deck). The equivalent tensioning method is used for single tensioning until the cable hanging work is completed.

[0150] Cable hanging system layout of cable threading machine: The cable threading process is adopted from top to bottom. A cable threading machine is arranged on the top of the tower. The cable threading machine on the top of the tower is used to provide power for threading a single steel strand. The cable threading system is mainly composed of a cable threading machine, connectors, plastic hoses, etc. The cable can be threaded first or while the material is being laid, depending on the site conditions.

[0151] A cable threading machine is arranged on the top of the tower. The length of the pre-stored steel strands in the cable threading machine is calculated according to the tower height and the storage position of the cable drum. The pre-stored steel strands are lowered by the cable threading machine, passed through the steering device under the tower column, led out and connected with the bridge deck steel strands, and then the pre-loaded steel strands are pulled to the top of the tower and passed through the PE pipe until they are anchored.

[0152] The steering device is fixed to the embedded parts on the bridge deck below the side wall of the bridge deck tower and is firmly fixed by welding with angle steel. It only serves to deflect the steel strands and is subjected to small forces, so no force calculation is required.

[0153] When installing the cable strand, it is also necessary to install the tower and beam end anchors. The technical requirements for anchor installation are as follows: (1) The anchor holes at the tensioning end and the fixed end are arranged horizontally in each row of holes. The anchor holes at both ends correspond to each other and there should be no misalignment. The position of the nuts should be adjusted properly. (2) The center line of the anchor is consistent with the center line of the anchor pad; (3) The anchor grouting hole is at the bottom and the exhaust hole is at the top.

[0154] When installing the cable-stayed cable strand, if there is enough space on the bridge deck, the HDPE pipe is welded on the bridge deck, otherwise it is welded on the trestle. Before welding the HDPE pipe, the welding length should be reviewed to avoid the situation where the HDPE pipe is insufficient in length due to thermal expansion and contraction after later operation. At the same time, during welding, the coaxiality, welding temperature, heating time, switching time, welding pressure, cooling and holding time, etc. should be controlled according to the technical briefing requirements to ensure the welding quality. Before hoisting the HDPE sheath pipe, various integral accessories at the beam end and tower end, such as the beam end PE connection device, shock absorber adjustment protective pipe, beam end protective steel pipe, thermoplastic sleeve and tower end PE connection device, shock absorber adjustment protective pipe, etc., should be assembled and fixed according to the drawing position (can be fixed on the clamp), and the steel strand should be tensioned according to the cable force that meets the verticality to make the sleeve straighten and lift to the designed angle to facilitate the next step of hanging the cable.

[0155] The process flow of a single rope hanging is as follows: (1) The steel strand is placed on a cable drum near the tower column; (2) The cable threading machine pulls the fixed-end steel strand from the bridge deck to the PE pipe opening outside the tower; (3) The cable threading machine passes the steel strand from the PE pipe opening to the waterproof cover opening; (4) The cable is switched outside the tower; (5) After pulling inside the tower to meet the tensioning length, the clamp is temporarily anchored; (6) The steel strand at the tower end is pulled into the tower; (7) After the bottom of the beam is reversed and the clamp is temporarily anchored, the tower end is notified to tension; (8) The tensioning jack is installed inside the tower and tension is performed according to the monitoring instructions; (9) The next steel strand is passed through in a cycle; For the single cable threading sequence, the cables are hung simultaneously in the middle and side spans and upstream and downstream of each pair of cable stays; to ensure that the steel strands are not twisted, the following principles must be followed when threading each cable bundle: Install row by row from top to bottom, and install the same row from outside (outside of the bridge deck) to inside (inside of the bridge deck); the anchor holes at the tensioning end and the fixed end must correspond one to one; use the equivalent tensioning method to tension a single steel strand and hang the cable according to the design requirements and monitoring instructions.

[0156] In order to make the tension of each steel strand in each cable uniform, the equal tensioning method is adopted, that is, the tension of each steel strand is monitored by the sensor reading, and the actual cable force measured by the sensor is fed back to the intelligent control box, and equal tension is achieved by controlling the control box.

[0157] In order to reduce the influence of verticality, the sensor is installed on the first steel strand of the second row. The installation order is: conical support, plum blossom support - sensor body - single-hole working anchor and tool clip. Therefore, the first row sets the reference cable tension, selects the conversion oil pressure, and then adjusts to the over-tension gear for tensioning. After the tension reaches the set reference cable tension, it will automatically maintain the pressure; until the sensor is installed, it is adjusted back to the equal-tension gear for automatic tensioning.

[0158] Install a pressure sensor on the first steel strand of the second row at the tensioning end and tension it to the reference tensioning cable force. When the next steel strand is about to be tensioned, the cable force of the installed steel strand will change due to structural deformation or temperature changes, and the sensor will also change accordingly. According to this change value, adjust the tensioning oil pressure of the steel strand to make it the same as the existing cable force of the steel strand with the sensor installed, and then anchor it. Similarly, the tension of each steel strand will be controlled according to the change of the pressure sensor, that is, the tension of each steel strand will be the same as the existing tension of the steel strand with the sensor installed. The purpose of over-tensioning the first row of steel strands of the anchor is to straighten the PE pipe and try to eliminate the influence of the deadweight of the PE pipe on the tension of the steel strand installed on the sensor. When the last steel strand is tensioned, the tension of the first row of steel strands is supplemented according to the cable force value on the display. If the cable force value is greater than the average cable force of a single strand, it is released to the average value; if it is less than the average cable force value of a single strand, the cable force is supplemented to the average cable force, and finally the sensor component is removed.

[0159] There are three main cable tension adjustments, namely the second and third tensioning during the construction process and the cable tension adjustment of the entire bridge.

[0160] If some cable numbers do not meet the requirements of overall tensioning due to space or other reasons, they need to be adjusted using the single-wire tensioning method. The cable force adjustment process is the same as that of single-wire tensioning.

[0161] After the cable is completed, the cable tightening and shock absorber installation work can be carried out without affecting the cable force monitoring.

[0162] Finally, the cable-stayed cables need to be protected, including corrosion protection of the cable body, corrosion protection inside the anchor head, and corrosion protection of the anchor head end face, clips, and exposed steel strands. Specific embodiment 6: This embodiment further illustrates the installation of steel bars and prestressed pipes on the basis of Specific Embodiment 1. The installation of steel bars in the installation of steel bars and prestressed pipes is as follows: before tying the bottom plate steel bars, the specific positions of the steel bars shall be marked on the pre-installed bottom mold according to the dimensions of the design drawings, and then the steel bars shall be tied. The steel bars shall be processed into semi-finished products in batches in the steel bar processing room and transported to the site for installation and forming. The connection of the steel bars must ensure the welding quality, and the number of steel bars connected in the same section should not exceed 50%.

[0164] 1) The order of steel bar binding is bottom plate steel bar → longitudinal rib steel bar → partition plate steel bar → top plate steel bar → embedded parts.

[0165] 2) The measures to be taken during construction are to hold the anchor plate perpendicular to the center axis of the spiral reinforcement and weld it in advance. The anchor plate is nailed to the end plate and tightened with screws instead of nails to prevent it from being pulled out a certain distance during vibration, ensuring that the plate is perpendicular to the pipeline.

[0166] When strengthening the pipeline fixing mesh, in order to prevent the pipeline from deformation and displacement, a fixing mesh is set every 1m.

[0167] 3) Specific requirements The steel bar binding must be firm and have sufficient rigidity to ensure that the web and the diaphragm can support themselves without deformation after binding. The steel bar joints should be staggered to ensure that the joint rate in the same section exceeds 50%. The joint staggered spacing should not be less than 35d (d steel bar diameter) and should not be less than 50cm. The distance between the steel bar joint and the steel bar bend should not be less than 10 times the steel bar diameter, and should not be located at the maximum bending moment of the component; Plastic protective layer pads should be installed between the steel bars and the formwork according to the designed protective layer thickness. The pads should be tied tightly to the steel bars and staggered. Tie bars should be installed between the steel meshes (bottom plate, web plate, top plate) and the spacing should be controlled according to the design requirements. After the steel reinforcement is tied, the on-site technicians will conduct a comprehensive inspection to check the content and errors, and control according to the requirements. After the self-inspection is passed, the supervision engineer will be asked to check; The reinforcement between the bottom plate, top plate and web plate is arranged in plum blossom shape. Both ends must be tied tightly or the straight hook ends must be welded (one end of the reinforcement is a semicircular hook and the other end is a straight hook) to prevent the vibration from unhooking and loosening; Sufficient plastic protective layer pads should be set between the steel mesh and the formwork of the lower layer of the bottom plate and the lower layer of the top plate, and the broken rings should be filled after installation; The embedded guardrail steel bars inside and outside the bridge deck should be installed neatly, in a straight line vertically and with consistent height. Specific embodiment 7: This embodiment further illustrates the installation of steel bars and prestressed pipes on the basis of specific embodiment 1. The installation of prestressed pipes in the installation of steel bars and prestressed pipes includes pipe installation and conflict resolution measures between pipes and steel bars. When installing the pipes, the prestressed pipes of the beams are all made of plastic corrugated pipes with holes and vacuum grouting technology. The installation of the prestressed pipes of the main beams is carried out simultaneously with the steel bars, and the corrugated pipes are fixed by U-shaped steel bar clamps. If there is a conflict between the main bars and the steel bundle corrugated pipes due to special reasons, the conflict resolution measures for the steel bars are specifically as follows: according to the markings in the construction drawings, if the prestressed anchorage interferes with the steel bars, the steel bars are moved to both sides of the prestressed sleeves; if the prestressed steel bars conflict with the steel, the main bars can be fine-tuned. If they need to be cut off, equal strength reinforcement measures need to be taken. Specific embodiment 8: This embodiment further illustrates the pouring of concrete on the basis of the specific embodiment 1. During the concrete pouring, the order of pouring concrete is to first symmetrically pour the main longitudinal ribs on both sides and then pour from the bridge span direction to the main pier direction. During the pouring, the concrete is poured in horizontal layers and oblique sections according to the cross section of the beam. The front and rear pouring distance between the upper layer and the lower layer is not less than 1.5m, and the pouring thickness of each layer does not exceed 30cm. During the concrete pouring process, attention is paid to making the concrete pour into the mold evenly to avoid a large amount of concentrated pouring into the mold. An experienced concrete worker is assigned to be responsible for vibration. The vibration is carried out using an inserted vibrator, and the moving spacing does not exceed 1.5 times its effective radius. A spacing of 5 to 10cm should be maintained with the side mold, and the lower layer of concrete is inserted about 5 to 10cm. All parts are vibrated and compacted. The sign of compaction is that the concrete stops sinking, no more bubbles, the surface is flat, and there is slurry. After each vibration is completed, the vibrator is slowly pulled out to avoid collision with the template, steel bars, prestressed pipes and other embedded parts. Concrete maintenance is also required after pouring. Specific embodiment 9: This embodiment further explains the prestressed construction in the beam body on the basis of the specific embodiment 1, and the prestressed construction in the beam body includes g1, prestressed steel bundle processing and installation; e2, main beam prestressing tensioning; e3, prestressed channel grouting and anchor sealing.

[0171] When constructing prestress in the beam, the prestressing materials and equipment must be prepared first, including the preparation of steel strands, anchors, corrugated pipes, and tensioning equipment. Before the tensioning construction, detailed instructions, static calculations of tensioning stress and elongation should be submitted to the supervision engineer for approval. In order to verify whether the implemented prestressing meets the design requirements, it is necessary to conduct a prestressing channel friction test on the main beam of the bridge during the cantilever construction process. Through the test, the actual friction data is obtained to guide the actual prestressing tensioning construction. Before carrying out prestressed construction, you also need to understand the prestressing tensioning sequence, tensioning construction process, tensioning procedures, and the requirements for cleaning anchors and anchor pads.

[0172] The prestressing sequence is to tension the longitudinal prestressing tendons first, and then the transverse plate prestressing tendons. The top plate transverse prestressing needs to be tensioned one segment later.

[0173] The requirements for tensioning include: (1) Longitudinal prestressed tendons (large) of longitudinal beams are tensioned symmetrically upstream and downstream; (2) Longitudinal prestressed tendons (small tendons) of plates are tensioned symmetrically from both sides to the middle and upstream and downstream; (3) Prestressed tendons of transverse diaphragms are tensioned at both ends; (4) Transverse prestressed tendons of top plates (lagging one section) are tensioned symmetrically upstream and downstream in the direction of 0#~N# blocks.

[0174] The tensioning construction process is as follows: The construction procedure for tensioning the longitudinal steel strand bundle: clean the anchors and anchor pads, cut off the excess corrugated pipes → remove rust from the steel strands, cut the materials, bundle, make bundle heads, and thread the bundles → cut off the excess steel strands, install working anchors, jacks and tool anchors → proceed after the concrete of the beam section reaches more than 90% of the design strength and the age is not less than 5d → cut off the excess steel strands after the tensioning is completed and qualified → seal the anchors and grouting.

[0175] The prestressing tendon tensioning procedure is: 0 → initial stress → σcon (holding load for 5 minutes) → anchoring (measuring elongation); The requirements for cleaning anchors and anchor pads are as follows: clean the cement slurry and concrete on the anchors and anchor pads; clear the grouting holes on the anchor pads to ensure smooth grouting channels; handle the misalignment at the connection between the anchor pads and the corrugated pipes to make the connection smooth; remove the excess corrugated pipes in the anchor pads. Check whether the anchor pads are correctly placed and whether they are perpendicular to the hole. If there are any problems, handle them first. Do not use anchors and clips that cannot be cleaned of rust or are damaged.

[0176] After understanding the above situation, the preparatory work for tensioning is carried out. The preparatory work for tensioning includes: inspection work before tensioning, cutting off excess steel hinge wires, installing working anchors and clips, installing jacks and tool anchors, and tool clips.

[0177] After finishing the tensioning preparation work, prestressing is carried out. At the beginning of prestressing, check that the oil pipe connection is reliable and correct, start the oil pump, slightly tighten the steel hinge wire, and then adjust the position of the jack to make its center basically consistent with the axis of the hole to ensure that the steel hinge wire can stretch freely and reduce friction. At the same time, adjust the tool clip to clamp the steel hinge wire to ensure that each steel hinge wire is evenly stressed. Then, the main oil cylinders of the jacks are slowly filled with oil at both ends to make the elongation of both ends basically consistent. After the initial tension force (0.1σcon) is loaded, the oil supply is stopped. After checking that the clamp is in good condition, a line is drawn to mark it. Continue to add oil to the jack until the controlled tension is reached. The tension value is mainly determined by the reading of the oil pressure gauge, and is checked by the elongation value of the prestressed steel strand. The retraction of the anchor at each end is controlled within 6mm; After the oil pressure reaches the tensioning tonnage, close the main oil cylinder oil circuit and maintain it for 5 minutes. Measure the elongation of the steel strand and check it. After maintaining it for 5 minutes, if the oil pressure drops slightly, add oil to the oil pressure value of the designed tonnage, the jack returns oil, the clamp automatically locks, and the tensioning of the bundle is completed. Make records in time. The total number of broken wires and slipped wires in the whole beam shall not exceed 0.5% of the total number of steel wires, and no more than one broken wire in a bundle shall be broken, and they shall not be on the same side; When the steel strand is too long to be tensioned in place at one time, multiple tensioning cycles are required. The operating methods and steps for multiple tensioning are the same as those described above, except that the anchor tension (stress) of the previous cycle is used as the initial value of this cycle, and this cycle is repeated until the final controlled tension is reached.

[0178] The measurement method of the elongation of the hinged wire bundle is as follows: the corresponding extension of the jack cylinder is measured under the corresponding tensioning force, and the difference between the extension of the jack cylinder under the initial tensioning force and the final tensioning force in each tensioning cycle is used as the elongation of the steel hinged wire bundle in this tensioning cycle. The sum of the elongations of each tensioning cycle is the elongation of the steel wire bundle between the initial tensioning force and the controlled tensioning force.

[0179] The calculation formula of the actual elongation of the steel strand △L is: △L=∑△L1+△L2. In the formula, △L1 is the measured elongation between the initial tension force and the controlled tension force; △L2 is the elongation between zero and the initial tension force, and its value is calculated from the elongation between 0.1σcon and 0.2σcon.

[0180] The tensioning of the stranded wire bundle adopts the dual control method of tensioning force and elongation value, that is, after the tensioning force reaches the design requirement, if the error between the actual elongation value and the theoretical value is between -6% and +6%, it means that the tensioning of this bundle of steel strands is qualified. Otherwise, although the tensioning force has reached the design requirement, the error between the actual elongation value and the theoretical elongation value exceeds the standard, the construction is suspended and the tensioning is continued after the cause is analyzed and dealt with.

[0181] The reasons for the excessive elongation are analyzed from the following aspects: the reliability of the tensioning equipment, i.e. the accuracy of the tensioning force; the accuracy of the friction resistance and deviation coefficient of the corrugated pipe channel; the deviation between the calculated value and the actual value of the elastic modulus of the steel hinge wire; the reasons for the measurement and calculation of the elongation, such as not considering the elongation value of the steel hinge wire in the jack, etc. If everything is normal, seal the end of the anchor and grout as soon as possible. Specific embodiment 10: This embodiment further explains step f on the basis of specific embodiment 1, wherein the lowering of the hanging basket in step f and then the walking anchoring and template lifting and installation specifically include the following steps: f1, removing the inner mold chamfering oblique support, rotating the chamfering template to vertical, and installing the inner mold arch frame lifting system boom; f2, lowering the inner mold arch frame to the bottom, removing the inner mold support rod, rotating the inner mold to the arch frame template, and the outer mold horizontally moving outward; f3, lowering the thrust jack, loosening the thrust piece from the beam body, and removing the rear anchor system; f4, lowering the middle anchor boom, synchronously lifting the tail balance jack until the C-hook roller falls into the slide slot, and the tail reaction wheel rotates into place and is fixed; f5, removing the middle anchor system, installing the hanging basket walking traction system and reaction device, lowering the tail balance jack, and completing the preparations for hanging basket walking; f6, before the hanging basket walks, removing all anchor rod groups, and conducting a comprehensive inspection of all anchor rod groups. The height after the side formwork falls down is to avoid the conflict between the component and the concrete boundary of the beam body. The side and middle span hanging baskets move symmetrically. The track plate is padded with fine sand to make it dense and flat. The hanging basket moves steadily and straightly. The oil top tensioning times and walking distances on both sides are consistent. The walking error on both sides of the hanging basket is kept within 2cm. The inner edge line of the hanging basket bottom plate is consistent with the inner edge line of the bottom surface of the beam body concrete to ensure that the hanging basket does not deviate. Before the hanging basket moves to the last stroke, observe the position of the anchor group eyelet according to the two symmetrical points on the upstream and downstream sides. After walking in place, ensure that the position corresponds accurately; f7, the walking traction system and the reaction device are removed, the middle anchor system is installed, the tail balance jack is lifted to the bottom of the beam, and the reaction wheel is loosened and rotated to a horizontal state; f8, the middle anchor boom is lifted, and the tail balance jack is lowered synchronously. When the thrust seat contacts the bottom of the beam, the hanging basket is lifted and the rear anchor system is installed; f9, the thrust jack is lifted and the thrust piece is fixed in place.

[0183] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly efficient construction method for symmetrical suspended pouring of the main beam of a cable-stayed bridge based on a front support cable hanging basket, characterized in that: The construction adopts the symmetrical hanging pouring method of the front support hanging basket, including the following steps: A. Installation of hanging basket; B. Installation of bottom membrane; C. Installation and tensioning of inclined cables; D. Installation of steel bars and prestressed pipes; E. Installation of end membranes; F. Concrete pouring; G. Prestressing construction in the beam body; H. Lowering the hanging basket and then carrying out the walking anchoring of the hanging basket and the lifting and installation of the formwork. After completion, the construction is completed; The hanging basket is installed by hoisting after assembly, and the corresponding assembly site is selected according to the location of the bridge pier; The concrete used in concrete pouring is a concrete with good fluidity, workability, water retention, cohesion and bulk density. The concrete needs to be poured evenly into the mold and then vibrated to make it dense. Prestressing requires multiple tensioning cycles. A deviation correction mechanism is provided at the rear of the hanging basket.

2. The method for symmetrically suspended pouring of the main beam of a cable-stayed bridge based on a front-support cable hanging basket according to claim 1 is characterized in that: The hanging basket in the hanging basket installation in step A includes a main longitudinal beam, a C-shaped hook, a front crossbeam, a middle crossbeam, a rear crossbeam, a middle anchor rod, a rear anchor rod, a walking reverse roller, a lifting mechanism, a thrust mechanism, a template system and a traction system. The front crossbeam, the middle crossbeam and the rear crossbeam are respectively arranged at the front, middle and rear parts of the inner side of the main longitudinal beam, the lower part of the C-shaped hook is connected to the middle part of the outer side of the main longitudinal beam, the lower end of the middle anchor rod is connected to the middle crossbeam, and the lower end of the rear anchor rod is connected to the rear crossbeam. The walking reverse roller is rotatably arranged at the tail of the main longitudinal beam, and the template system is arranged on the inner side of the main longitudinal beam. The lifting mechanism includes an inner mold frame lifting mechanism, a middle anchor rod lifting mechanism and a tail balancing jack. The top of the inner mold frame lifting mechanism is connected to the inner mold arch frame of the template system, the top surface of the middle anchor rod lifting mechanism is connected to the middle anchor rod, the tail balancing jack is arranged on the rear top surface of the main longitudinal beam, and the thrust mechanism is arranged at the rear of the main longitudinal beam.

3. The method for symmetrical cantilever casting of the main beam of a cable-stayed bridge based on a front support cable hanging basket according to claim 2 is characterized in that: The installation of the hanging basket in the step A includes the installation of the hanging basket at the bridge pier near the bank of the river and the installation of the hanging basket at the bridge pier in the middle of the river. The installation of the hanging basket at the bridge pier near the bank of the river includes land assembly and hoisting, and the installation of the hanging basket at the bridge pier in the middle of the river includes assembly and hoisting on the long-mileage side and assembly and hoisting on the short-mileage side. The assembly in the long-mileage side assembly and hoisting is carried out on the pier, and the assembly in the short-mileage side assembly and hoisting is assembled on the ship.

4. The method for symmetrical suspended casting of the main beam of a cable-stayed bridge based on a front fulcrum cable hanging basket according to claim 1 is characterized in that: The bottom membrane installation in step B includes the assembly and installation of the outer mold at the cantilever end of the main beam and the assembly and installation of the inner mold. The outer mold at the cantilever end of the main beam is assembled using the pier body mold, and the inner mold is assembled using a newly purchased large-block standardized steel mold. Before installation, rust is removed and the mold paint is applied. The outer mold and the inner mold of the cantilever end of the main beam are both opened with PCV pipes and reinforced with steel rods.

5. The method for symmetrical cantilever casting of the main beam of a cable-stayed bridge based on a front support cable hanging basket according to claim 1 is characterized in that: The installation of the inclined cables in step C includes the following steps: installing temporary measures on the construction basket, then locking the No. 1 cable and one cable, pouring half of the concrete after completion, performing the second cable, pouring concrete for the second time, prestressing, converting the No. 1 cable and three cables, repeating the above steps to install cables No. 2 to No. N, and after the construction of all the inclined cables is completed, the closing section is constructed, and after the construction of the closing section, constant pressure loading is performed, and the entire bridge is adjusted. After the adjustment of the entire bridge is completed, accessories are installed and anti-corrosion is performed. In the steps, one cable is preloaded to 50%, the template is fine-tuned and fixed, and when half of the concrete is poured, the two cables are preloaded to 100%.

6. The method for symmetrical cantilever casting of the main beam of a cable-stayed bridge based on a front support cable hanging basket according to claim 1 is characterized in that: The installation of steel bars and prestressed pipes is specifically that before tying the bottom plate steel bars, the specific positions of the steel bars should be marked on the pre-installed bottom formwork according to the dimensions of the design drawings, and then the steel bars should be tied. The steel bars are divided into types and batches and processed into semi-finished products in the steel bar processing room and transported to the site for installation and forming. The connection of the steel bars must ensure the welding quality, and the number of steel bars connected in the same section should not exceed 50%.

7. The method for symmetrically suspended casting of the main beam of a cable-stayed bridge based on a front-support cable hanging basket according to claim 1 is characterized in that: The installation of prestressed pipes in the installation of steel bars and prestressed pipes includes pipe installation and conflict resolution measures between pipes and steel bars. During pipe installation, plastic corrugated pipe holes are used for beam prestressed pipes, and vacuum grouting technology is used. The installation of main beam prestressed pipes is carried out simultaneously with steel bars, and the corrugated pipes are fixed by U-shaped steel bar clamps. If there is a conflict between the main bars and the steel bundle corrugated pipes due to special reasons, the conflict resolution measures for the steel bars are as follows: according to the markings in the construction drawings, if the prestressed anchorage interferes with the steel bars, the steel bars are moved to both sides of the prestressed sleeves; if the prestressed steel bars conflict with the steel, the main bars can be fine-tuned. If they need to be cut off, equal strength reinforcement measures need to be taken.

8. The method for symmetrical cantilever casting of the main beam of a cable-stayed bridge based on a front support cable hanging basket according to claim 1 is characterized in that: When pouring concrete, the order of pouring concrete is to pour the main longitudinal ribs on both sides symmetrically first, and then pour from the span direction to the main pier direction. When pouring concrete, it is horizontally layered and obliquely segmented according to the cross-section of the beam. The front and rear pouring distance between the upper and lower layers is not less than 1.5m, and the pouring thickness of each layer does not exceed 30cm. During the concrete pouring process, pay attention to making the concrete enter evenly to avoid a large amount of concentrated entry into the mold. An experienced concrete worker is assigned to be responsible for vibration. The vibration is carried out using an inserted vibrator with a moving spacing not exceeding 1.5 times its effective radius. A spacing of 5 to 10cm should be maintained with the side mold. Insert the lower layer of concrete about 5 to 10cm, and vibrate all parts to make them dense. The sign of density is that the concrete stops sinking, no more bubbles, the surface is flat, and there is slurry. After each vibration is completed, slowly pull out the vibrator to avoid collision with the formwork, steel bars, prestressed pipes and other embedded parts. Concrete maintenance is also required after pouring.

9. The method for symmetrical cantilever casting of the main beam of a cable-stayed bridge based on a front support cable hanging basket according to claim 1 is characterized in that: The prestressing construction in the beam body includes g1, prestressed steel bundle processing and installation; e2, main beam prestressing tensioning; e3, prestressed channel grouting and anchor sealing.

10. The method for symmetrical cantilever casting of the main beam of a cable-stayed bridge based on a front support cable hanging basket according to claim 1 is characterized in that: The lowering of the hanging basket in step f and then the walking anchoring and template lifting and installation specifically include the following steps: f1, removing the inner mold chamfer oblique support, rotating the chamfer template to vertical, and installing the inner mold arch frame lifting system boom; f2, lowering the inner mold arch frame to the bottom, removing the inner mold support rod, rotating the inner mold to the arch frame template, and the outer mold horizontally moving outward; f3, the thrust jack is lowered, the thrust piece is loosened from the beam body, and the rear anchor system is removed; f4, the middle anchor boom is lowered, and the tail balance jack is synchronously lifted until the C-hook roller falls into the slide slot and the tail reaction wheel is rotated and fixed in place; f5, the middle anchor system is removed, the hanging basket walking traction system and reaction device are installed, the tail balance jack is lowered, and the preparation for the hanging basket to walk is completed; f6, before the hanging basket walks, all anchor rod groups are removed, and the height of all side templates after falling is fully checked to avoid components There is no conflict with the concrete boundary of the beam body. The side and middle span hanging baskets move symmetrically. The track plate is padded with fine sand to make it dense and flat. The hanging basket moves steadily and straightly. The oil top tensioning times and walking distances on both sides are consistent. The walking error on both sides of the hanging basket is kept within 2cm. The inner edge line of the hanging basket bottom plate is consistent with the inner edge line of the bottom surface of the beam body concrete to ensure that the hanging basket does not deviate. Before the hanging basket moves to the last stroke, observe the position of the anchor group eyelet according to the two symmetrical points on the upstream and downstream sides. After walking in place, ensure that the position corresponds accurately; f7, the walking traction system and the reaction device are removed, the middle anchor system is installed, the tail balance jack is lifted to the bottom of the beam, and the reaction wheel is loosened and rotated to a horizontal state; f8, the middle anchor boom is lifted, and the tail balance jack is lowered synchronously. When the thrust seat contacts the bottom of the beam, the hanging basket is lifted and the rear anchor system is installed; f9, the thrust jack is lifted and the thrust piece is fixed in place.

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