Construction method of large-cross-border asymmetric small-side-to-middle-ratio separated hybrid beam cable-stayed bridge

Abstract

The invention discloses a large-cross-border asymmetric small-side-to-middle-ratio separated hybrid beam cable-stayed bridge construction method, which relates to the field of cable-stayed bridge construction and comprises the steps of construction preparation stage, bridge lower structure construction, bridge upper structure construction, bridge closure construction, construction monitoring and quality control and the like. Through foundation construction and foundation expansion, the stability of the lower structure of the large-span bridge is improved, and the conditions that the bridge is complex in stress due to an asymmetric structural form, the stress proportion of a main span can be increased due to a small side-to-middle ratio, and the proportion of loads borne by the main span is increased are handled, the closure section selects a temperature interval with the minimum structural deformation to conduct closure, and the temperature range is wide. And the expansion amount is reserved, so that accurate splicing of the separated hybrid beam and smooth transmission of internal force are realized, and the stability of the bridge is further ensured.

Description

Technical Field

[0001] The invention relates to the technical field of cable-stayed bridge construction, and in particular to a construction method for a large-cross-border asymmetric small-side-to-center ratio separated hybrid beam cable-stayed bridge. Background Art

[0002] A cable-stayed bridge, also known as a cable-stayed bridge, is a type of bridge in which the main beam is directly pulled on the bridge tower by many cables. It is a structural system composed of a pressure-bearing tower, a tensioned cable, and a bending beam. It can be regarded as a multi-span elastically supported continuous beam with cables replacing piers. It can reduce the bending moment in the beam body, lower the building height, reduce the structural weight, and save materials. A cable-stayed bridge is mainly composed of a cable tower, a main beam, and a cable-stayed cable.

[0003] However, in the existing technology, cable-stayed bridges with large main spans and small side-to-center ratios have significant advantages when crossing large obstacles such as rivers and straits, but their construction difficulty is also much higher than that of traditional cable-stayed bridges. Among them, the closure construction is the final stage of bridge construction and is particularly important. The existing construction methods cannot guarantee the construction of the closure section well. Summary of the invention

[0004] The object of the present invention is to provide a construction method for a large-cross-border asymmetric small-side-ratio separated hybrid beam cable-stayed bridge to solve the problems raised by the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge, comprising the following steps:

[0006] S1. Construction preparation stage, including construction site layout, construction technology preparation, and material and equipment preparation;

[0007] S2. Bridge substructure construction, mainly including foundation construction, firstly bored pile foundation construction, then foundation expansion;

[0008] The construction of bridge piers begins with the installation of pier formwork, followed by steel bar tying, and finally concrete pouring and curing;

[0009] S3, bridge superstructure construction, mainly including steel beam fabrication and installation, concrete beam construction and cable-stayed cable construction;

[0010] S4. Bridge closure construction mainly includes:

[0011] S41. Temperature control: Select the appropriate closure temperature. For large-span asymmetric small-side medium-ratio separated hybrid beam cable-stayed bridges, temperature has a greater impact on the structure. Through long-term temperature observation, determine the deformation law of the structure at different temperatures, and select the temperature range with the smallest structural deformation for closure. Closure operations can be performed at night or when the temperature changes are small;

[0012] S42, Line shape adjustment: Before the closure, the line shape of the bridge is accurately adjusted. By adjusting the cable force of the inclined cable and the elevation of the beam section, the beams on both sides of the closure section are accurately connected in space. The line shape of the beam is monitored in real time using measuring equipment such as a total station to ensure that the line shape adjustment meets the design requirements;

[0013] S43. Determine the length of the joint section: Determine the length of the joint section based on factors such as the temperature during the jointing and structural deformation. The length of the joint section should reserve an appropriate amount of expansion and contraction to accommodate the structural expansion and contraction caused by temperature changes. Determine the optimal length of the joint section through calculation and simulation analysis;

[0014] S44, Installation and connection of joint sections: Lift the joint section to the joint position and use temporary connection measures to fix the joint section to the beams on both sides. During the fixing process, the position of the joint section must be accurate. For the joint section of the hybrid beam, attention should be paid to the connection quality of the steel beam and the concrete beam, and then permanent connection should be made, such as welding the steel beam, pouring concrete, etc., to complete the construction of the joint section;

[0015] S5. Construction monitoring and quality control mainly include construction monitoring and quality control, covering the entire construction process.

[0016] Preferably, the construction site layout includes arranging material storage sites, machinery and equipment parking and operation areas, and temporary facility construction;

[0017] The construction technical preparation includes review of construction drawings, preparation of construction plans and construction technical briefing;

[0018] The material and equipment preparation includes material procurement and inspection as well as equipment selection and commissioning.

[0019] Preferably, the bored pile foundation construction comprises the following steps:

[0020] A1. Drilling construction: Select appropriate drilling equipment according to geological conditions;

[0021] A2. Fabrication and installation of steel cage;

[0022] A3. Concrete pouring: Use the conduit method to pour underwater concrete.

[0023] Preferably, the step of expanding the foundation includes:

[0024] B1. Excavation of foundation pit: Excavate the foundation pit according to the foundation size and geological conditions;

[0025] B2. Base treatment: level and compact the base;

[0026] B3. Formwork installation and concrete pouring.

[0027] Preferably, the steps of manufacturing and installing the steel beam include:

[0028] C1. Steel cutting and processing: Cut and process the steel beams according to the design drawings;

[0029] C2. Steel beam assembly and welding: Assemble the steel beam on the assembly platform to ensure that each component of the steel beam is accurately aligned;

[0030] C3. Selection of erection method: Select the steel beam erection method according to the span of the bridge and site conditions;

[0031] C4. Transportation and lifting of steel beams.

[0032] Preferably, the concrete beam construction steps include:

[0033] D1. Determine the connection method. According to the design of the hybrid beam, determine the connection method of the steel beam and the concrete beam;

[0034] D2. Preparation for joint section construction: Before the joint construction, clean and treat the joints between the steel beam and the concrete beam;

[0035] D3. Installation of connection components: Install shear nails and pressure plate connection components according to design requirements;

[0036] D4. Concrete pouring of the joint section: After the installation of the connecting components is completed, the concrete pouring of the joint section is carried out.

[0037] Preferably, the stay cable construction steps include:

[0038] E1. Cable production: Cables are generally made of high-strength steel wire or steel strands;

[0039] E2. Cable-stayed cable transportation: Due to its large length and weight, special measures must be taken during transportation;

[0040] E3. Selection of hanging method: Select the hanging method according to the length and weight of the inclined cable;

[0041] E4. Cable head installation: accurately connect the cable head of the inclined cable with the anchor points of the main beam and the bridge tower;

[0042] E5. Selection and calibration of cable-stayed cable tensioning equipment: Select appropriate cable-stayed cable tensioning equipment;

[0043] E6. Tensioning sequence and control: Determine the tensioning sequence of the cable-stayed cables according to the design requirements.

[0044] Preferably, the construction monitoring includes:

[0045] Deformation monitoring: During the construction of a bridge, deformation monitoring is performed on key parts of the bridge, such as the main beam and bridge tower;

[0046] Stress monitoring: Install stress sensors on the main beams, bridge towers and cable-stayed cables to monitor the stress changes of the structure in real time;

[0047] Cable force monitoring: For inclined cables, cable force sensors or other measurement methods are used to monitor the cable force.

[0048] Preferably, the quality control includes:

[0049] Raw material quality control: strict quality control of steel beams, concrete raw materials, cables and other raw materials;

[0050] Construction process quality control, strictly control the construction process in each construction link such as steel beam production, concrete pouring, and cable construction;

[0051] Finished product protection quality control: During the construction process, pay attention to the finished product protection of the completed structure.

[0052] Preferably, the stress sensor installed at the inclined cable position comprises a sensor body and a connecting block, one side of the sensor body is fixedly connected to a movable block, both ends of the movable block are fixedly connected to a long bolt, two ends of the connecting block are respectively movably connected to the first side arm and the second side arm, the middle part of the first side arm is provided with a first slide groove, the middle part of the second side arm is provided with a second slide groove, two groups of the long bolts are respectively slidably clamped in the inner walls of the first slide groove and the second slide groove, the middle part of the movable block is rotatably connected to a main screw, the main screw is threadedly connected to the middle part of the connecting block, the two ends of the movable block are slotted to respectively accommodate the first side arm and the second side arm, the upper end of the main screw is movably connected to the handle rod, the lower side of the movable block is welded with a resist column, one end of the resist column is threadedly connected with an auxiliary screw, the resist column and the auxiliary screw constitute a calibration assembly, and the other two groups of the calibration assemblies are respectively welded to the lower ends of the first side arm and the second side arm.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] 1. In the present invention, the stability of the lower structure of the long-span bridge is improved by foundation construction and expansion of the foundation. In order to cope with the situation that the asymmetric structural form makes the bridge stress complicated and the small side-to-center ratio increases the stress proportion of the main span and the load proportion borne by the main span, the joint section is selected to be closed in the temperature range with the smallest structural deformation, and the expansion and contraction amount is reserved to achieve accurate splicing of the separated hybrid beams and smooth internal force transmission, thereby further ensuring the stability of the bridge.

[0055] 2. In the present invention, the first side arm and the second side arm are pressed closer to each other while the movable block moves downward, and the positioning components under the two are driven to move closer to each other. At the same time, the positioning component under the movable block also approaches the inclined cable and gradually clamps the inclined cable. The three sets of positioning components enable the stress sensor installed at the inclined cable position to adapt to inclined cables of different sizes, thereby improving the scope of application. The auxiliary screws in the positioning components are rotated separately so that the lower ends thereof are against the inclined cables, thereby the sensor body is fittedly installed on the surface of the inclined cables, and the stress changes of the inclined cables are monitored in real time, and timely responses are made to improve the structural safety of the inclined cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flow chart of a construction method of a large cross-border asymmetric small side-to-side ratio separated hybrid beam cable-stayed bridge according to the present invention;

[0057] Figure 2 It is a first three-dimensional structural schematic diagram of a stress sensor installed at a stay cable position in a construction method of a large-cross-border asymmetric small-side medium-ratio separated hybrid beam cable-stayed bridge according to the present invention;

[0058] Figure 3 It is a second three-dimensional structural schematic diagram of a stress sensor installed at the cable-stayed portion in a construction method of a large-cross-border asymmetric small-side medium-ratio separated hybrid beam cable-stayed bridge according to the present invention.

[0059] In the figure: 1. sensor body; 2. handle bar; 3. main screw; 4. connecting block; 5. first side arm; 6. movable block; 7. support column; 8. second side arm; 9. second slide groove; 10. first slide groove; 11. auxiliary screw; 12. long bolt. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0061] Example 1: Reference Figure 1As shown: A construction method for a large cross-border asymmetric small side-to-center ratio separated hybrid beam cable-stayed bridge, comprising the following steps:

[0062] 1. Construction preparation stage, including construction site layout, construction technology preparation, and material and equipment preparation;

[0063] (I) Construction site layout

[0064] Material storage area

[0065] According to the material types and order of use, the stacking areas of steel beams, prefabricated concrete beams, cables, steel bars, cement and other materials shall be divided. For steel beam components, special support and protection measures shall be set up to prevent deformation and rust of components. The concrete beam prefabrication site shall ensure sufficient space for prefabrication and maintenance, and be equipped with corresponding maintenance equipment.

[0066] Mechanical equipment parking and operation area

[0067] Plan the parking and operation areas for mechanical equipment such as cranes, concrete mixers, transport vehicles, and cable-stayed tensioning equipment. The operating radius of the crane should cover the main construction area, and the carrying capacity of its walking channel and outriggers should be considered. For cable-stayed tensioning equipment, it should be set in a suitable position to facilitate operation and control of cable force.

[0068] Temporary facilities construction

[0069] Build temporary facilities such as office area, living area, warehouse, etc. The office area should have good communication and office conditions to facilitate construction management. The living area should meet the living and living needs of construction workers, including dormitories, canteens, bathrooms and other facilities. The warehouse should have moisture-proof and fire-proof functions and be used to store small construction tools, accessories and materials.

[0070] (II) Construction technical preparation

[0071] Construction drawing review

[0072] Organize construction technicians, designers and supervisors to review the construction drawings. Carefully review the size, material specifications, connection structure and other details of the bridge structure, and communicate with the design unit in a timely manner to resolve any questions and problems in the drawings. In particular, ensure accurate understanding of the design of key parts such as the connection parts of the hybrid beam and the anchor points of the inclined cables.

[0073] Construction plan preparation

[0074] Prepare a detailed construction plan based on the project characteristics and construction site conditions. This includes the foundation construction plan, beam segment prefabrication and erection plan, cable installation and tensioning plan, closure plan, etc. The construction plan should clearly define the construction sequence, construction technology, quality control standards and safety measures. For special cases such as large cross-border, asymmetric, small side-to-center ratio and mixed beams, targeted technical measures should be formulated.

[0075] Construction technology disclosure

[0076] Provide construction technical briefings to construction teams and operators. The briefings include construction technology, quality requirements, safety precautions, etc. Use a combination of written briefings and on-site demonstrations to ensure that operators understand the construction requirements. For key processes, such as cable tensioning, operators must receive special training.

[0077] (III) Preparation of materials and equipment

[0078] Material procurement and inspection

[0079] Procure steel beams, concrete raw materials, cable stays and other materials according to design requirements. Steel beams should be produced by reliable manufacturers, and their material, size, weld quality, etc. should be strictly inspected. Concrete raw materials should meet the corresponding standards, and raw material tests and mix ratio design should be carried out. Cable stays should be subjected to cable force tests and flaw detection inspections to ensure their strength and quality.

[0080] Equipment selection and commissioning

[0081] According to the construction needs, select appropriate cranes, transport vehicles, concrete pouring equipment, cable-stayed cable tensioning equipment, etc. The crane should be selected according to parameters such as lifting capacity, lifting height and operating radius. Concrete pouring equipment must ensure the pouring quality and speed of concrete. The cable-stayed cable tensioning equipment must have a high-precision cable force control function. After the equipment is brought to the site, it must be debugged and tested to ensure that the equipment works normally.

[0082] Second, the construction of the bridge substructure mainly includes foundation construction, first of all, bored pile foundation construction, followed by foundation expansion;

[0083] The construction of bridge piers begins with the installation of pier formwork, followed by steel bar tying, and finally concrete pouring and curing;

[0084] The details are as follows: (I) Foundation construction

[0085] Bored pile foundation

[0086] Drilling construction: Choose appropriate drilling equipment according to geological conditions, such as rotary drill or impact drill. During the drilling process, control parameters such as drilling speed and mud density. For areas with complex geology, such as rock layers or karst caves, take appropriate drilling measures. For example, when encountering rock layers, use impact drilling or replace the drill bit, and when encountering karst caves, fill them before continuing drilling.

[0087] Fabrication and installation of steel cage: Fabricate the steel cage at the construction site to ensure that the spacing and welding quality of the steel bars meet the design requirements. The steel cage should be installed vertically and centered, and a crane should be used to slowly place the steel cage into the drilled hole.

[0088] Concrete pouring: Use the conduit method to pour underwater concrete. Before pouring, the conduit should be checked for tightness. During the pouring process, the pouring speed of concrete and the buried depth of the conduit should be controlled to prevent quality problems such as broken piles and mud inclusions.

[0089] Expanding the base

[0090] Excavation of foundation pit: Excavation of foundation pit is carried out according to the foundation size and geological conditions. Mechanical excavation and manual excavation are adopted. When approaching the base, a certain thickness of soil layer should be reserved for manual excavation to avoid disturbing the base soil. At the same time, drainage and support work of the foundation pit should be done well to prevent the foundation pit from collapsing.

[0091] Base treatment: level and compact the base. For soft foundations, reinforcement treatment is required, such as replacement filling method, cement mixing piles, etc., to improve the base bearing capacity.

[0092] Formwork installation and concrete pouring: Install the foundation formwork to ensure the strength, rigidity and stability of the formwork. The formwork should be installed firmly and tightly to prevent leakage. When pouring concrete, vibrate it layer by layer to ensure that the concrete is dense.

[0093] (II) Pier construction

[0094] Pier formwork installation

[0095] Choose the appropriate formwork according to the shape and size of the pier. For higher piers, climbing formwork or sliding formwork can be used. The formwork installation must ensure its verticality and surface flatness, and the joints between the formworks must be tight. During the formwork installation process, sufficient tension bolts and supports must be set to ensure that the formwork does not deform during the concrete pouring process.

[0096] Rebar tying

[0097] Tie the steel bars in the formwork. The specifications, quantity and spacing of the steel bars must meet the design requirements. For the joints of the steel bars, appropriate connection methods should be used, such as welding or mechanical connection, and inspections should be carried out in accordance with regulations. During the tying process, care should be taken to protect the steel bars to prevent them from being contaminated or damaged.

[0098] Concrete pouring and curing

[0099] Use a concrete pump or crane to pour concrete. Concrete should be poured and vibrated in layers, and the vibration should be dense to avoid quality problems such as honeycombs and rough surfaces. After the concrete is poured, it should be maintained in time. Covering and moisturizing maintenance or spraying curing agents can be used to ensure the normal development of concrete strength.

[0100] 3. Bridge superstructure construction, mainly including steel beam fabrication and installation, concrete beam construction and cable-stayed cable construction;

[0101] (I) Steel beam production and installation

[0102] Steel beam production

[0103] Steel cutting and processing: Cut and process the steel beams according to the design drawings. Use CNC cutting equipment to ensure cutting accuracy, and grind and correct the cut steel. For complex nodes of steel beams, special processing technology should be used to ensure that the size and shape of the nodes meet the requirements.

[0104] Steel beam assembly and welding: Steel beams are assembled on the assembly platform to ensure that the various components of the steel beams are accurately aligned. Welding is a key process in the production of steel beams, and appropriate welding processes and welders must be selected. Welding process assessment must be performed before welding, and welding parameters such as current, voltage, and welding speed must be controlled during welding. After welding is completed, non-destructive testing of the welds must be performed, such as ultrasonic testing and X-ray testing, to ensure weld quality.

[0105] Steel beam installation

[0106] Selection of erection method: Select the steel beam erection method according to the span of the bridge and the site conditions, such as cantilever assembly method, floating crane erection method, etc. The cantilever assembly method is suitable for large-span bridges. By setting hangers on the installed beam segments, the steel beams are assembled section by section. The floating crane erection method is suitable for water construction. The steel beams are hoisted into place as a whole or in sections using a floating crane.

[0107] Transportation and hoisting of steel beams: During transportation, reinforcement measures should be taken to prevent deformation of the steel beams. During hoisting, appropriate cranes or floating cranes should be selected according to the weight and length of the steel beams. During the hoisting process, the balance and stability of the steel beams should be ensured, and the steel beams should be hoisted slowly to the installation location.

[0108] (II) Concrete beam construction

[0109] Precast concrete beams

[0110] Formwork engineering: Make high-precision prefabricated formwork for concrete beams. The formwork must have sufficient strength, rigidity and sealing to ensure the dimensions and surface quality of the concrete beams. A release agent is set in the formwork to facilitate concrete demoulding.

[0111] Rebar engineering: Tie the steel bars in the formwork according to the design requirements. The layout of the steel bars should be accurate, and for prestressed steel bars, attention should be paid to their positioning and protection. At the same time, the protective layer pads of the steel bars should be installed to ensure the thickness of the concrete protective layer.

[0112] Concrete pouring and curing: Use appropriate concrete mix ratio for concrete pouring. During the pouring process, vibrate the concrete fully to make it dense. After pouring, it must be cured at the prefabrication site, and the curing time and conditions must meet the requirements of the specifications.

[0113] Concrete beam erection

[0114] Selection of erection equipment: Select appropriate erection equipment, such as a bridge erection machine, according to the weight of the concrete beam and the erection height. The lifting capacity, span and travel speed of the bridge erection machine must meet the construction requirements.

[0115] Erection process: Use a bridge erection machine to lift the prefabricated concrete beam to the installation location. During the erection process, attention should be paid to the balance and accurate alignment of the beam. For the connection between adjacent beam sections, the connection quality should be guaranteed. For example, when wet joint connection is used, the concrete pouring and vibration should be done well.

[0116] (III) Hybrid beam connection construction

[0117] Connection method confirmed

[0118] According to the design of the hybrid beam, determine the connection method between the steel beam and the concrete beam, such as using a steel-concrete joint section. The design of the joint section must ensure smooth internal force transmission between the steel beam and the concrete beam, and structural measures such as shear nails and pressure plates can be used.

[0119] Construction technology

[0120] Preparation for joint section construction: Before the joint construction, clean and treat the joints of the steel beam and concrete beam. For the steel beam, ensure that its surface is clean and rust-free; for the concrete beam, ensure that its joint surface is flat.

[0121] Installation of connection components: Install shear nails, pressure plates and other connection components according to design requirements. The welding of shear nails should be firm, and the installation of pressure plates should be accurate and flat. During the installation process, the construction quality should be strictly controlled and appropriate testing methods should be used for quality inspection.

[0122] Concrete pouring of the joint section: After the connection components are installed, the concrete pouring of the joint section is carried out. The concrete mix ratio should be specially designed to ensure its strength and bonding performance with the connection components. During the pouring process, it should be fully vibrated to ensure that the concrete is dense and tightly bonded with the connection components.

[0123] (IV) Cable-stayed cable construction

[0124] Cable-stayed cable production and transportation

[0125] Cable production: Cables are generally made of high-strength steel wires or steel strands. During the production process, the steel wires or steel strands must be strictly inspected to ensure that their strength and elastic modulus meet the requirements. The steel wires or steel strands are bundled and protected, such as using hot-extruded polyethylene and other protective methods to prevent the steel wires from rusting.

[0126] Cable transportation: Due to its length and weight, special measures must be taken during transportation. It can be transported by winding it on a special reel. During transportation, the cable should be protected from damage, such as collision with sharp objects and squeezing.

[0127] Cable-stay installation

[0128] Selection of cable hanging method: Select the cable hanging method according to the length and weight of the inclined cable, such as direct cable hanging by crane, soft traction cable hanging, etc. For long and heavy cables, the soft traction cable hanging method can be used, using winches and other equipment to gradually pull the inclined cable to the installation location.

[0129] Cable head installation: accurately connect the cable head of the inclined cable to the anchor points of the main beam and the bridge tower. During the connection process, the installation accuracy of the cable head must be ensured, and special anchoring devices and sealing measures must be used to prevent the cable head from loosening and rainwater from entering.

[0130] Cable tensioning

[0131] Selection and calibration of tensioning equipment: Select appropriate cable tensioning equipment, such as jacks and oil pumps. The tensioning equipment should have high-precision pressure and stroke control functions. Before use, the tensioning equipment should be calibrated to determine the relationship between its tensioning force and the pressure gauge reading.

[0132] Tensioning sequence and control: Determine the tensioning sequence of the cable according to the design requirements. Generally, the staged tensioning method is adopted. During the tensioning process, the cable force and the deformation of the main beam should be monitored in real time. The cable force is measured by sensors and other equipment, and the tensioning parameters are adjusted according to the cable force and deformation data to ensure that the cable force meets the design requirements and the deformation of the main beam is within the allowable range.

[0133] 4. Bridge closure construction, details are as follows:

[0134] (I) Preparation of joint conditions

[0135] Temperature control

[0136] Select the appropriate closure temperature. For large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridges, temperature has a greater impact on the structure. Through long-term temperature observation, the deformation law of the structure at different temperatures is determined, and the temperature range with the smallest structural deformation is selected for closure. Closure operations can be performed at night or when the temperature changes are small.

[0137] Linear Adjustment

[0138] Before the bridge is closed, the alignment of the bridge is precisely adjusted. By adjusting the cable force of the inclined cable and the elevation of the beam section, the beams on both sides of the closure section are accurately connected in space. The alignment of the beam is monitored in real time using measuring equipment such as a total station to ensure that the alignment adjustment meets the design requirements.

[0139] (II) Construction of the closure section

[0140] Determination of the length of the joint section

[0141] The length of the joint section is determined based on factors such as temperature and structural deformation during the joint. The length of the joint section should reserve appropriate expansion and contraction to accommodate the structural expansion and contraction caused by temperature changes. The optimal length of the joint section is determined through calculation and simulation analysis.

[0142] Installation and connection of joint sections

[0143] Lift the joint section to the joint position and use temporary connection measures to fix the joint section to the beams on both sides. During the fixing process, ensure that the position of the joint section is accurate. For the joint section of the hybrid beam, pay attention to the connection quality of the steel beam and the concrete beam. Then make permanent connections, such as welding steel beams, pouring concrete, etc., to complete the construction of the joint section;

[0144] 5. Construction monitoring and quality control, which mainly includes construction monitoring and quality control, covering the entire construction process;

[0145] (I) Construction monitoring

[0146] Deformation monitoring

[0147] During the construction of the bridge, deformation monitoring is carried out on key parts of the bridge, such as the main beam and bridge tower. The displacement, settlement and other deformation data of the structure are measured regularly using measuring equipment such as total stations and levels. A deformation monitoring database is established to analyze the deformation data, detect abnormal structural deformation in a timely manner, and take corresponding adjustment measures.

[0148] Stress monitoring

[0149] Stress sensors are installed on the main beam, bridge tower and cable to monitor the stress changes of the structure in real time. The stress monitoring data can reflect the stress state of the structure during the construction process. By comparing it with the design calculation value, it can be judged whether the structure is safe. If the stress monitoring value exceeds the allowable range, the construction sequence or parameters should be adjusted in time to ensure the safety of the structure.

[0150] Cable force monitoring

[0151] For the cable-stayed cables, cable force sensors or other measurement methods are used to monitor the cable force. Cable force is one of the key parameters for the construction control of cable-stayed bridges. Changes in cable force will affect the overall force and line shape of the bridge. During the construction process of cable-stayed cable tensioning and beam segment installation, the cable force is monitored in real time, and the tensioning process is adjusted according to the cable force monitoring results to ensure that the cable force meets the design requirements.

[0152] (II) Quality Control

[0153] Raw material quality control

[0154] Strict quality control is carried out on raw materials such as steel beams, concrete raw materials, and cable stays. A raw material inspection system is established to inspect each batch of raw materials, including the mechanical properties, chemical composition, and appearance quality of the materials. Only raw materials that pass the inspection can be used for construction.

[0155] Construction process quality control

[0156] Strictly control the construction process in each construction link, such as steel beam production, concrete pouring, and cable-stayed cable construction. For steel beam welding, the quality of the weld must be guaranteed; for concrete pouring, the density and strength of the concrete must be guaranteed; for cable installation and tensioning, the cable force and anchoring quality must be guaranteed. Establish a quality inspection system, conduct quality inspections on each process, and promptly rectify unqualified processes.

[0157] Finished product protection quality control

[0158] During the construction process, pay attention to the finished product protection of the completed structure. For the surface of the steel beam, prevent it from rusting and collision; for the concrete structure, prevent its surface from being scratched and contaminated. In the subsequent construction process, take reasonable protection measures, such as setting up guardrails, covering with protective cloth, etc.

[0159] Embodiment 2: According to Figure 2-Figure 3As shown, the stress sensor installed at the inclined cable position includes a sensor body 1 and a connecting block 4, a movable block 6 is fixedly connected to one side of the sensor body 1, and long bolts 12 are fixedly connected to both ends of the movable block 6, and the first side arm 5 and the second side arm 8 are movably connected to the two ends of the connecting block 4, respectively. A first slide groove 10 is opened in the middle of the first side arm 5, and a second slide groove 9 is opened in the middle of the second side arm 8. Two groups of long bolts 12 are slidably clamped on the inner walls of the first slide groove 10 and the second slide groove 9 respectively, and a main screw rod 3 is rotatably connected to the middle of the movable block 6, and the main screw rod 3 is threadedly connected to the middle of the connecting block 4. Slots at both ends of the movable block 6 respectively accommodate the first side arm 5 and the second side arm 8, and the upper end of the main screw rod 3 is movably connected to the handle rod 2, and a support column 7 is welded to the lower side of the movable block 6, and one end of the support column 7 is threadedly connected to an auxiliary screw 11, and the support column 7 and the auxiliary screw 11 constitute a calibration assembly, and the other two groups of calibration assemblies are respectively welded to the lower ends of the first side arm 5 and the second side arm 8.

[0160] In this embodiment, in the initial state, the main screw 3 is in the highest position, the first side arm 5 and the second side arm 8 clamp the inclined cable from both sides, the handle bar 2 is held and rotated, thereby driving the main screw 3 to rotate in the middle thread of the connecting block 4, thereby pushing the movable block 6 downward, and the long bolts 12 at both ends of the movable block 6 are respectively installed in the first slide groove 10 of the first side arm 5 and the second slide groove 9 of the second side arm 8, the second slide groove 9 and the first slide groove 10 are in an "eight" shape, and the first side arm 5 and the second side arm 8 are pressed simultaneously during the downward movement of the movable block 6. The side arms 8 approach each other and drive the alignment components below the two to approach each other. At the same time, the alignment component below the movable block 6 also approaches the inclined cable and gradually clamps the inclined cable. The three sets of alignment components enable the stress sensor installed at the inclined cable position to adapt to inclined cables of different sizes, thereby improving the scope of application. By rotating the auxiliary screws 11 in the alignment components respectively so that their lower ends are against the inclined cables, the sensor body 1 is fittedly installed on the surface of the inclined cables, and the stress changes of the inclined cables are monitored in real time, and timely responses are made to improve the structural safety of the inclined cables.

[0161] 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 construction method for a large cross-border asymmetric small side-to-center ratio separated hybrid beam cable-stayed bridge, characterized in that: The following steps are involved: S1. Construction preparation stage, including construction site layout, construction technology preparation, and material and equipment preparation; S2. Bridge substructure construction, mainly including foundation construction, firstly bored pile foundation construction, then foundation expansion; The construction of bridge piers begins with the installation of pier formwork, followed by steel bar tying, and finally concrete pouring and curing; S3, bridge superstructure construction, mainly including steel beam fabrication and installation, concrete beam construction and cable-stayed cable construction; S4. Bridge closure construction mainly includes: S41, Temperature control: Select the appropriate closure temperature, determine the deformation law of the structure at different temperatures through long-term temperature observation, and select the temperature range with the smallest structural deformation for closure; S42, Line shape adjustment: Before the closure, the line shape of the bridge is accurately adjusted by adjusting the cable force of the inclined cable and the elevation of the beam section to accurately connect the beams on both sides of the closure section in space, and the line shape of the beam is monitored in real time using measuring equipment; S43, determining the length of the joint section: the length of the joint section should reserve a certain amount of expansion and contraction, and the optimal length of the joint section is determined through calculation and simulation analysis; S44, installation and connection of joint section: hoist the joint section to the joint position, fix the joint section to the beams on both sides by temporary connection measures, and then make permanent connection; S5. Construction monitoring and quality control mainly include construction monitoring and quality control, covering the entire construction process.

2. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The construction site layout includes the layout of material storage sites, machinery and equipment parking and operation areas, and the construction of temporary facilities; The construction technical preparation includes review of construction drawings, preparation of construction plans and construction technical briefing; The material and equipment preparation includes material procurement and inspection as well as equipment selection and commissioning.

3. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The bored pile foundation construction comprises the following steps: A1. Drilling construction: Select appropriate drilling equipment according to geological conditions; A2. Fabrication and installation of steel cage; A3. Concrete pouring: Use the conduit method to pour underwater concrete.

4. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The steps of expanding the base include: B1. Excavation of foundation pit: Excavate the foundation pit according to the foundation size and geological conditions; B2. Base treatment: level and compact the base; B3. Formwork installation and concrete pouring.

5. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The steps of making and installing the steel beam include: C1. Steel cutting and processing: Cut and process the steel beams according to the design drawings; C2. Steel beam assembly and welding: Assemble the steel beam on the assembly platform to ensure that each component of the steel beam is accurately aligned; C3. Selection of erection method: Select the steel beam erection method according to the span of the bridge and site conditions; C4. Transportation and lifting of steel beams.

6. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The concrete beam construction steps include: D1. Determine the connection method. According to the design of the hybrid beam, determine the connection method of the steel beam and the concrete beam; D2. Preparation for joint section construction: Before the joint construction, clean and treat the joints between the steel beam and the concrete beam; D3. Installation of connection components: Install shear nails and pressure plate connection components according to design requirements; D4. Concrete pouring of the joint section: After the installation of the connecting components is completed, the concrete pouring of the joint section is carried out.

7. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The construction steps of the cable-stayed cable include: E1. Cable production: Cables are generally made of high-strength steel wire or steel strands; E2. Cable-stayed cable transportation: Due to its large length and weight, special measures must be taken during transportation; E3. Selection of hanging method: Select the hanging method according to the length and weight of the inclined cable; E4. Cable head installation: accurately connect the cable head of the inclined cable with the anchor points of the main beam and the bridge tower; E5. Selection and calibration of cable-stayed cable tensioning equipment: Select appropriate cable-stayed cable tensioning equipment; E6. Tensioning sequence and control: Determine the tensioning sequence of the cable-stayed cables according to the design requirements.

8. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1 is characterized by: The construction monitoring includes: Deformation monitoring: During the construction of a bridge, deformation monitoring is performed on key parts of the bridge, such as the main beam and bridge tower; Stress monitoring: Install stress sensors on the main beams, bridge towers and cable-stayed cables to monitor the stress changes of the structure in real time; Cable force monitoring: For inclined cables, cable force sensors or other measurement methods are used to monitor the cable force.

9. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 1, characterized in that: The quality control includes: Raw material quality control: strict quality control of steel beams, concrete raw materials, cables and other raw materials; Construction process quality control, strictly control the construction process in each construction link such as steel beam production, concrete pouring, and cable construction; Finished product protection quality control: During the construction process, pay attention to the finished product protection of the completed structure.

10. The construction method of a large cross-border asymmetric small side ratio separated hybrid beam cable-stayed bridge according to claim 8, characterized in that: The stress sensor installed at the position of the inclined cable comprises a sensor body (1) and a connecting block (4); a movable block (6) is fixedly connected to one side of the sensor body (1); and long bolts (12) are fixedly connected to both ends of the movable block (6); The two ends of the connecting block (4) are movably connected to a first side arm (5) and a second side arm (8), a first slide groove (10) is provided in the middle of the first side arm (5), a second slide groove (9) is provided in the middle of the second side arm (8), and two groups of long bolts (12) are respectively slidably engaged with the inner walls of the first slide groove (10) and the second slide groove (9); The middle part of the movable block (6) is rotatably connected to a main screw rod (3), and the main screw rod (3) is threadedly connected to the middle part of the connecting block (4). The two ends of the movable block (6) are slotted to respectively accommodate the first side arm (5) and the second side arm (8). The upper end of the main screw rod (3) is movably connected to a handle rod (2). The lower side of the movable block (6) is welded with a support column (7), and one end of the support column (7) is threadedly connected to an auxiliary screw rod (11). The support column (7) and the auxiliary screw rod (11) constitute a calibration assembly. The other two groups of the calibration assembly are respectively welded to the lower ends of the first side arm (5) and the lower ends of the second side arm (8).

Images