Business line continuous beam steel concrete composite beam construction method

Abstract

The invention discloses a construction method for a steel-concrete composite beam of a continuous beam of a business line, and relates to the field of bridge construction. Comprising nine operation steps of temporary consolidation and support construction, No.0 block construction, hanging basket cantilever casting construction, side span cast-in-place section construction, steel-concrete mixed section construction, swivel construction, side span closure and system conversion, steel-concrete composite beam construction and bridge deck system construction, and construction operation of the continuous beam steel-concrete composite beam of the business line is completed. According to the construction method, the construction mode that suspension grouting construction is conducted firstly, then rotation construction is conducted, and finally middle-span middle-span steel beam pushing is conducted is adopted, one-time large-span and long-distance stable construction of the steel-concrete continuous beam is achieved in the parallel business line state, and meanwhile the construction period is effectively shortened.

Description

Technical Field

[0001] The invention relates to the field of bridge construction, and in particular to a construction method for a continuous beam steel-concrete combined beam of an operating line. Background Art

[0002] Continuous rigid frame bridges currently widely use cantilever casting construction methods or rotation construction methods. The cantilever casting method requires the bridge body to be segmented, and the number of segments is huge, which inevitably prolongs the construction period; the cantilever casting method itself has high risks and many uncontrollable factors, which has long been a constraint on the development of large-span continuous rigid frames; the subsequent rotation construction method, although it avoids the segmentation of the bridge body during the construction process and reduces the risks in the hanging basket construction, but after the construction is completed, there are often large-span cast-in-place sections that cannot be formed in one go and require subsequent scaffolding to be erected for the construction of the cast-in-place sections.

[0003] Therefore, how to provide a construction method for continuous steel-concrete beams on operating lines, which adopts a construction method of first suspended pouring construction, then rotation construction, and finally pushing the steel beam in the middle of the span, to achieve one-time large-span and long-distance stable construction of steel-concrete continuous beams under the parallel operating line state, and at the same time, effectively shorten the construction period, has become a technical problem that needs to be urgently solved by personnel in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for continuous beam steel-concrete combined beams of operating lines, which adopts a construction method of first suspended pouring construction, then rotation construction, and finally pushing the steel beam in the middle of the span, so as to achieve one-time large-span and long-distance stable construction of steel-concrete continuous beams, and at the same time, effectively shorten the construction period.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a construction method for a continuous beam steel-concrete combined beam of an operating line, comprising the following steps:

[0007] Step 1: Temporary consolidation and support construction, which provides vertical support by means of temporary anchoring, and cooperates with permanent supports to resist various unbalanced moments generated during the continuous beam segmented cantilever casting process;

[0008] Step 2: Construction of Block 0, using the support as the main bearing structure, and setting up a working platform on the support to carry out subsequent template installation, steel bar binding, concrete pouring and maintenance, prestressing tendons, and prestressed pipe grouting to complete the cast-in-place operation of Block 0 of the continuous beam;

[0009] Step 3: Hanging basket cantilever casting construction: hang the hanging basket as the main bearing structure on the constructed beam section, and install the formwork, steel bars, prestressed pipes, concrete pouring, prestressing tensioning and grouting of the next beam section on the hanging basket. After completing one stage of the cycle, control the hanging basket to move forward to carry out the next stage of cantilever casting until the cantilever casting operation is completed;

[0010] Step 4: Construction of cast-in-place section of side span. The straight section of side span is cast in one time. During the construction, the position of anchor plate and prestressed pipe is controlled, and reserved holes and embedded parts are accurately set.

[0011] Step 5: Construction of the steel-concrete mixed section: After the steel-concrete combined section is transported to the designated location by a flatbed transport vehicle, a hanging basket rear anchor, as well as a winch and a guide pulley anchor pull ring are set at the corresponding position of the bridge deck to carry out the lifting operation of the steel-concrete mixed section;

[0012] Step 6: Rotation construction: the rotation beam is arranged with an integral cantilever cast-in-place beam, and the pier and beam are rotated horizontally as a whole, and the rotation construction process must be carried out within the skylight point;

[0013] Step 7: Side span closure and system conversion. After the box girder is rotated and in place, the side span closure section is constructed. After the prestressing of the closure is completed, the temporary consolidation support is completely cut along the bottom of the beam and the surface of the pier top structure using a rope saw, and then broken into small pieces and lifted off. At the same time, other supporting structures on the pier top are cleaned, and the connection between the upper and lower seat plates of the permanent support is released, so that the support can slide normally, and the beam is dropped to form a single-span cantilever structure.

[0014] Step 8: Construction of steel-concrete composite beams: First, use crawler cranes to complete the hoisting operation of steel box beam segments; second, perform multiple jacking operations until the jacking operation of the steel beam is completed, and remove the front guide beam and the rear guide beam, and install the beam drop bracket; finally, drop the beam as a whole, weld the joint section, and remove the beam drop bracket;

[0015] Step 9: Bridge deck construction. After the steel box girder jointing operation is completed, the bridge deck crane is removed, other debris is cleaned up, the steel beam is fully inspected and local painting is completed. Then, after the prefabricated production and maintenance of the bridge deck reaches the design strength, the bridge deck construction work is carried out.

[0016] Preferably, the operation steps of temporary consolidation and support construction in step 1 include:

[0017] 1) Pre-embedded steel bars: According to the design drawings, when constructing the top section of the pier, temporary consolidation of prestressed fine-rolled threaded steel bars and pre-embedded steel bars are carried out;

[0018] 2) Installation of temporary consolidation formwork: after the concrete strength of the pier reaches the design requirements, the formwork installation operation is carried out;

[0019] 3) Temporary consolidation concrete pouring. To facilitate the subsequent removal of temporary supports, the height of the temporary support stop surface should be marked before concrete pouring, and a layer of sulfur mortar isolation layer should be poured on the top surface of the temporary consolidation pier before concrete pouring.

[0020] 4) Bearing installation: After the bearing is in place, gravity grouting is used to carry out grouting operations between the bearing lower base plate and the supporting pad stone and in the anchor bolt hole.

[0021] Preferably, the operation steps of the No. 0 block construction in step 2 include: support design and construction, support preloading and observation, formwork production and installation, steel bar binding, concrete pouring and maintenance, prestressing tensioning, and prestressed pipe grouting, a total of seven operation steps, to complete the cast-in-place operation of the No. 0 block;

[0022] The specific construction steps of the prestressed pipe grouting include:

[0023] 1) Try to evacuate the vacuum, start the vacuum pump, and make the negative pressure of the system reach 0.06-0.1Mpa. When the vacuum degree in the channel remains stable, stop the vacuum pump for 1 minute. If the pressure value decreases by no more than 0.02Mpa, it means that the channel meets the vacuum requirement; if the pressure value decreases by more than 0.02Mpa, the seal of the channel needs to be checked and repaired;

[0024] 2) Mixing: First, add water to the mixer and let it run idle for several minutes before mixing the cement. When the inner wall of the mixer is fully moistened, pour out the accumulated water. Secondly, pour the weighed water into the mixer and pour the cement during the mixing process. When the cement is completely added to the mixer, continue to stir until the cement and water are evenly mixed.

[0025] 3) Pour the admixture into the mixer and continue stirring for 5 to 15 minutes, then pour the stirred cement slurry into the slurry drum;

[0026] 4) Grouting, start the vacuum pump. When the vacuum degree in the channel is maintained at a negative pressure of 0.08Mpa, open the valve, start the grouting pump, and start the grouting operation. When the slurry passes through the transparent high-pressure pipe and reaches the three-way joint, open the slurry discharge valve and close the negative pressure container valve and the vacuum pump, and observe the slurry discharge at the waste slurry barrel. If the slurry discharge is smooth and stable and the consistency is consistent with the slurry in the slurry barrel, close the grouting pump and the valve at the other end, and start the grouting pump again to make the grouting pressure value reach 0.4Mpa until the grouting operation is completed;

[0027] 5) Carry out anchor pouring operation. Before pouring anchor concrete, the tensioning groove of the beam body should be roughened first, and waterproof coating should be applied within the anchor range for waterproofing treatment.

[0028] Preferably, the operation steps of the cast-in-place section construction of the side span in step 4 include: support design and construction, support acceptance, support pre-compression, formwork production and installation, steel bar installation and binding, concrete pouring and maintenance, and support removal, a total of seven operation steps, to complete the pouring and molding operation of the side span straight section concrete;

[0029] The specific construction steps for the support acceptance include:

[0030] 1) The position and elevation of the embedded parts of the bracket should be accurately set to meet the requirements of the pier installation accuracy. The bracket should be corrected in time during installation. The verticality deviation should be less than 1 / 500 of the pillar height, and the column top offset value should be less than 50mm;

[0031] 2) The installation of steel pipe brackets shall meet the following requirements:

[0032] a. Install in sections and layers according to the hoisting equipment and site conditions at the construction site;

[0033] b. The steel pipes and foundations and the steel pipe joints should be firmly connected, and the joint gaps should be tightly filled with steel plates;

[0034] c. The upper steel pipe can be installed only after the lower scissor brace connector is installed. Before the scissor brace is installed, temporary measures should be taken to reinforce and stabilize the steel pipe;

[0035] 3) The installation of crossbeams and longitudinal beams shall meet the following requirements:

[0036] a. Before installing the crossbeam and longitudinal beam, the installation position should be accurately marked, and the installation error should be less than 20mm;

[0037] b. After the beams are assembled into a whole, they should be hoisted into place, and the beams and pillars should be firmly connected; if there is a gap between the beams and their supports, they should be filled with steel plates and welded firmly;

[0038] c. Bailey beams and military beam truss beams should be assembled on a flat and solid site, and temporary stabilization measures should be taken;

[0039] d. The truss should be assembled into segments of one span or longer, and hoisted using a single piece or multiple pieces according to the hoisting capacity; the hoisting point should be set at a node 0.2 times the length of both ends of the truss beam. After the truss beam is in place, measures should be taken to ensure its lateral stability before loosening the hook;

[0040] e. When installing the crossbeam and longitudinal beam, the lateral bending should be strictly controlled, and the lateral bending sagitta should be less than 1 / 1000 of the span and not more than 20mm;

[0041] f. The installation of commonly used equipment for Bailey beams and military beams should comply with the relevant requirements of their user manuals.

[0042] Preferably, the operation steps for the construction of the steel-concrete mixed section in step five include: on-site assembly of segments, hoisting of the steel-concrete mixed section, installation of steel bars, pouring of concrete, tensioning and grouting of prestressed steel strands, a total of five operation steps, to complete the construction of the steel-concrete mixed section.

[0043] Preferably, the operation steps of the rotation construction in step 6 include: a total of two operation steps of trial rotation and formal rotation, to complete the construction work of the rotation;

[0044] The specific construction steps of the trial swivel include:

[0045] 1) Preparation work before trial rotation construction:

[0046] a. Remove the support pads. Before the rotation is implemented, the sand box between the support legs and the slideway needs to be removed and the debris cleaned up;

[0047] b. Remove the waterproof and dustproof facilities between the upper and lower turntables, and remove the temporary fixing devices;

[0048] c. Slideway lubrication: Before the rotation is implemented, the slideway should be lubricated again to ensure that the resistance on the slideway is at the minimum state;

[0049] 2) Test rotation:

[0050] a. Pre-tighten the steel strands. Use a jack to pre-tighten the steel strands one by one with a force of 5 to 10KN according to the principle of first the inner layer and then the outer layer. Then reduce the pre-tightening force from 10KN to 5KN one by one, and use the jack to tighten the steel strands as a whole under oil pressure to keep the force on each steel strand of the same traction rope consistent. Finally, adopt a symmetrical pre-tightening method and repeat it several times to ensure that each steel strand is evenly stressed.

[0051] b. Turn on the power of the main console and the pump station, start the pump station, and use the main console to control the two jacks to apply force to test rotation at the same time; if it cannot rotate, use the jacks to assist in pushing out force to overcome the static friction resistance and make the bridge rotate;

[0052] c. Carry out the test of two important data, rotation speed per minute and control point operation. The rotation speed per minute is used to measure the angle of the main bridge and the horizontal chord distance of the cantilever end per minute; the control point operation is used to measure the horizontal chord distance of the cantilever end for each point movement, so as to provide an operational basis for precise positioning after the swivel is initially in place;

[0053] d. Check whether the rotating structure is balanced and stable, whether there are any faults, and whether there are cracks in the key stress-bearing parts; if there are any abnormalities, the test run should be stopped, the cause should be found out and corresponding measures should be taken to rectify the situation before continuing the test run;

[0054] e. Before the test run is about to be completed, a limit steel should be inserted between the reaction seats to prevent over-rotation. After the test run stops, a steel wedge should be inserted into the support foot to fix the ball joint;

[0055] The specific construction steps of the formal rotation include:

[0056] 1) Preparation before the formal rotation

[0057] a. Determine the center of gravity of the rotating body, weigh the rotating part with a jack, and measure its friction coefficient;

[0058] b. Clean the circular slide, check the gap between the slide and the support foot, and apply silicone grease to the front end of the support foot walkway board;

[0059] c. Calibrate the horizontal jack, auxiliary jack and fine-tuning jack;

[0060] d. Perform installation and commissioning of the horizontal swivel jack, traction rope, anchor, and pump station accessories, and ensure that each strand of steel strand is straight, without hinges or kinks;

[0061] e. Install the booster jack and reverse thrust beam;

[0062] f. Install fine-tuning and control equipment, make various measurement and control signs, and mark the position of the bridge axis;

[0063] g. Carry out inspection operations on key parts;

[0064] h. After the rotating body has been stationary for 24 hours, various measurement data shall be reported to the monitoring team to confirm whether it is in a balanced state;

[0065] 2) Start, tension the traction jack synchronously, and apply force in stages at 100KN per stage until the footboard moves horizontally, observe and record the static friction resistance, and then reduce the force in stages until the normal speed is no more than 0.02rad / min;

[0066] 3) Horizontal rotation: the rotation is carried out according to the rotation operation time determined by the railway department. During the horizontal rotation process, the surveying personnel need to repeatedly observe the deviation of the pier axis and the elevation change of the beam end. At the same time, ensure that the angular velocity of the rotation is not greater than 0.02rad / min, the horizontal line speed of the main beam end is not greater than 1.0m / min, and ensure stability and safety during the rotation process;

[0067] 4) Rotate at a uniform speed, and start to reduce the rotation speed when the horizontal rotation is 1.5m away from the design position; rotate horizontally to 1m away from the design position, take inching operation, and cooperate with the measurement personnel to confirm the arc length of the beam end after inching; rotate horizontally to 0.1m away from the design position, stop rotating, and measure the axis. According to the difference, accurately inching control positioning to prevent over-rotation;

[0068] 5) Positioning:

[0069] a. After the swivel is in place, accurately adjust the swivel's posture and position, and use steel wedges to lock the upper and lower turntables;

[0070] b. Use the jacks installed on the top of the temporary pier to accurately adjust the elevation of the beam end and use steel wedges to pad;

[0071] c. After the beam is fine-tuned, complete the consolidation of the upper and lower caps;

[0072] d. The rotation power system should have both automatic and manual control functions. When the end of the main beam is about to reach 1.0m before the design position, the jog operation should be adopted and close cooperation with the surveying personnel should be carried out to obtain the maximum arc length rotation data during the operation;

[0073] e. Before inching operation and precision positioning, the upper structure should be leveled;

[0074] f. Set limit piles at appropriate locations to prevent over-rotation.

[0075] Preferably, the operation steps of side span closure and system conversion in step seven include: installation of common steel bars and prestressed pipes, closure locking design, closure locking, pouring of closure section concrete, prestressing construction, hanging basket removal, system conversion, a total of seven operation steps, to complete the construction work of side span closure and system conversion, the specific operation process is:

[0076] 1) When the strength and elastic modulus of the suspended cast segment concrete reach the design values ​​and the age is not less than 7 days, install the external support of the joint segment and temporarily tension it to lock the joint support;

[0077] 2) Select the time period with the lowest temperature in a day to pour the concrete of the side span closure section beam section;

[0078] 3) After the concrete strength and elastic modulus of the joint section reach the design value, the temporary longitudinal locking of the side piers will be removed, and tensioning will be done in sequence. The temporary cables will be tensioned to the designed tonnage, and the side span supports will be removed.

[0079] Preferably, the operation steps of the steel-concrete composite beam construction in step eight include: steel beam segmentation, guide beam and steel beam segment assembly, steel beam top-pushing construction, and steel beam jointing, a total of four operation steps, to complete the construction of the steel-concrete composite beam;

[0080] The steel beam top pushing construction specifically includes the following operation steps:

[0081] 1) Preparation and inspection before pushing:

[0082] a. Check whether the joints of all valves or hard pipes on the pump station are loose, and check whether the pressure regulating spring of the overflow valve is in a completely relaxed state;

[0083] b. Check whether the cable connection between the pump station starter cabinet and the hydraulic crawler is correct;

[0084] c. Check whether the oil pipe connection between the pump station and the main oil cylinder of the hydraulic crawler is correct;

[0085] d. Power on the system and check whether the rotation direction of the hydraulic pump main shaft is correct;

[0086] e. When the pump station is not started, manually operate the corresponding buttons in the control cabinet to check whether the solenoid valve and the stop valve are operating normally, and whether the stop valve number and the crawler number correspond;

[0087] f. Check the sensor, press 2L, 2L-, L+, L- of each hydraulic crawler stroke sensor to make the corresponding signal light in the control cabinet send a signal;

[0088] e. Inspection before sliding: Start the pump station and adjust a certain pressure to extend and retract the crawler cylinder: Check whether the oil pipes of chamber A and chamber B are connected correctly; check whether the stop valve can cut off the corresponding cylinder; check whether the inverter can speed up or slow down the extension and retraction speed of the corresponding cylinder when the current changes;

[0089] f. Preload: Adjust the pressure to keep the wedge clamps in the same locking state;

[0090] 2) Start pushing the steel beam:

[0091] a. First, the crawler crane is used to complete the hoisting operation of the steel box girder segment, and the linear adjustment and the welding of the yard mouth are completed in time; secondly, after the non-destructive testing is qualified, the node repainting operation is carried out, and the interface welding operation of the guide beam and the segment is completed;

[0092] b. Carry out the first round of pushing operation and ensure the safety and stability of the beam structure during the forward pushing process;

[0093] c. Carry out the second jacking operation and continue to push forward so that the front end of the structure is supported on the top surface of the reinforced concrete box girder;

[0094] d. Perform the third jacking operation, push forward again until the jacking operation is completed, then remove the front guide beam and the rear guide beam, and install the beam drop bracket;

[0095] 3) Steel beam lowering construction: After the steel beam is pushed into place, each crane is connected into a whole by two diamond trusses through a transverse mechanism. A hydraulic lifting device is installed at the front upper crossbeam of each diamond truss, and the beam lowering operation is completed by centralized control.

[0096] Preferably, the operation steps of the bridge deck system construction in step nine include: bridge deck installation, shield installation, railing installation, column installation, beam installation, beam inner sleeve, and other auxiliary construction, a total of seven operation steps to complete the construction of the bridge deck system.

[0097] Compared with the prior art, the beneficial technical effects of the present invention are:

[0098] The construction of Block 0 and the cantilever hanging basket were carried out in parallel with the operating line. The main piers 19 and 20 and Block 0 were cast in situ using the bracket method. The cast-in-situ section of the side span of Pier 18 was cast in situ using a full-height bracket with a buckle; the cast-in-situ section of the side span of Pier 21 was cast in situ using a beam-column type ground-type steel pipe bracket. After the symmetrical rotation beam section is cast in situ, the side spans on both sides are closed after the hinges are sealed, and the main span steel box beam segment is assembled on the main span of Pier 20. After the steel beam is assembled, the steel beam is pushed into place using the top-pushing method and then dropped to complete the middle span closure;

[0099] The main pier construction pre-buried pier beam consolidation parts as required, and pre-buried vertical prestressed tendons, brackets and related designs according to block No. 0, and carried out pier body capping construction. Install brackets, bottom molds, and side molds and complete the pre-compression brackets after acceptance. After completion, the No. 0 block was constructed according to the bracket method. After the construction of the No. 0 block was completed, the continuous beam was cantilevered with a hanging basket, and finally the side span cast-in-place section and the steel structure of the steel-concrete combined section were constructed.

[0100] In general, the construction method of the steel-concrete combined beam of an operating line continuous beam of the present invention adopts a construction method of first suspended pouring construction, then rotation construction, and finally pushing the steel beam in the middle of the span, so as to realize the stable construction of a large-span and long-distance steel-concrete continuous beam in a one-time manner under the state of parallel operating line, and at the same time, effectively shorten the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] The present invention will be further described below in conjunction with the accompanying drawings.

[0102] Figure 1 This is a construction process flow chart of a continuous beam steel-concrete combined beam of an operating line of the present invention;

[0103] Figure 2 This is the plan layout diagram of the block support No. 0 of the present invention;

[0104] Figure 3 This is a schematic diagram of layered casting of block No. 0 of the present invention;

[0105] Figure 4 This is a schematic diagram of the graded pre-compression loading process of the stent of the present invention;

[0106] Figure 5 This is a schematic diagram of the steel-concrete mixing section hoisting process of the present invention;

[0107] Figure 6 It is a schematic diagram of the construction process of the steel-concrete combined beam of the present invention. DETAILED DESCRIPTION

[0108] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0109] like Figure 1-6 As shown, a construction method for continuous beam steel-concrete combined beams of an operating line includes the following steps:

[0110] Step 1: Temporary consolidation and support construction, which provides vertical support by means of temporary anchoring, and cooperates with permanent supports to resist various unbalanced moments generated during the continuous beam segmented cantilever casting process;

[0111] Step 2: Construction of Block 0, using the support as the main bearing structure, and setting up a working platform on the support to carry out subsequent template installation, steel bar binding, concrete pouring and maintenance, prestressing tendons, and prestressed pipe grouting to complete the cast-in-place operation of Block 0 of the continuous beam;

[0112] Step 3: Hanging basket cantilever casting construction: hang the hanging basket as the main bearing structure on the constructed beam section, and install the formwork, steel bars, prestressed pipes, concrete pouring, prestressing tensioning and grouting of the next beam section on the hanging basket. After completing one stage of the cycle, control the hanging basket to move forward to carry out the next stage of cantilever casting until the cantilever casting operation is completed;

[0113] Step 4: Construction of cast-in-place section of side span. The straight section of side span is cast in one time. During the construction, the position of anchor plate and prestressed pipe is controlled, and reserved holes and embedded parts are accurately set.

[0114] Step 5: Construction of the steel-concrete mixed section: After the steel-concrete combined section is transported to the designated location by a flatbed transport vehicle, a hanging basket rear anchor, as well as a winch and a guide pulley anchor pull ring are set at the corresponding position of the bridge deck to carry out the lifting operation of the steel-concrete mixed section;

[0115] Step 6: Rotation construction: the rotation beam is arranged with an integral cantilever cast-in-place beam, and the pier and beam are rotated horizontally as a whole, and the rotation construction process must be carried out within the skylight point;

[0116] Step 7: Side span closure and system conversion. After the box girder is rotated and in place, the side span closure section is constructed. After the prestressing of the closure is completed, the temporary consolidation support is completely cut along the bottom of the beam and the surface of the pier top structure using a rope saw, and then broken into small pieces and lifted off. At the same time, other supporting structures on the pier top are cleaned, and the connection between the upper and lower seat plates of the permanent support is released, so that the support can slide normally, and the beam is dropped to form a single-span cantilever structure.

[0117] Step 8: Construction of steel-concrete composite beams: First, use crawler cranes to complete the hoisting operation of steel box beam segments; second, perform multiple jacking operations until the jacking operation of the steel beam is completed, and remove the front guide beam and the rear guide beam, and install the beam drop bracket; finally, drop the beam as a whole, weld the joint section, and remove the beam drop bracket;

[0118] Step 9: Bridge deck construction. After the steel box girder jointing operation is completed, the bridge deck crane is removed, other debris is cleaned up, the steel beam is fully inspected and local painting is completed. Then, after the prefabricated production and maintenance of the bridge deck reaches the design strength, the bridge deck construction work is carried out.

[0119] Specifically, the operation steps of temporary consolidation and support construction in step 1 include:

[0120] 1) Pre-embedded steel bars: According to the design drawings, when constructing the top section of the pier, temporary consolidation of prestressed fine-rolled threaded steel bars and pre-embedded steel bars are carried out;

[0121] 2) Installation of temporary consolidation formwork: after the concrete strength of the pier reaches the design requirements, the formwork installation operation is carried out;

[0122] 3) Temporary consolidation concrete pouring. To facilitate the subsequent removal of temporary supports, the height of the temporary support stop surface should be marked before concrete pouring, and a layer of sulfur mortar isolation layer should be poured on the top surface of the temporary consolidation pier before concrete pouring.

[0123] 4) Bearing installation: After the bearing is in place, gravity grouting is used to carry out grouting operations between the bearing lower base plate and the supporting pad stone and in the anchor bolt hole.

[0124] Specifically, during the segmented cantilever casting of the continuous beam, the permanent support cannot withstand the unbalanced moment generated during construction. Temporary anchoring measures are required during construction to provide vertical support and resist various unbalanced moments generated during construction. The temporary consolidation of the pier and beam adopts the temporary consolidation form of the pier top. The internal temporary consolidation is arranged on both sides of the top of the two main piers No. 19 and No. 20 along the bridge, symmetrically arranged front and back. The temporary consolidation of the pier and beam adopts φ32 prestressed fine-rolled threaded steel and φ32 HPB400 steel bars for temporary consolidation. The φ32 prestressed fine-rolled threaded steel anchor has a controlled stress of 705.5MPa, and the tension elongation per meter is about 0.353cm. The temporary consolidation concrete adopts C55, and the upper and lower temporary consolidation piers are isolated by No. 50 sulfur mortar. The temporary consolidation measures should be able to withstand the maximum vertical force of 22615.4KN at the middle support point, and the corresponding unbalanced bending moment is 16355.6KN.m.

[0125] Specifically, the matters needing attention in installing the support include:

[0126] 1) When installing the support and anchor bolts, use concrete wedges to adjust the four corners of the lower support plate to align the longitudinal centerline of the support. After it meets the design requirements, use non-shrinkage mortar to pour the anchor bolt holes to the support bottom cushion layer;

[0127] 2) Roughen the surface of the supporting stone at the bearing position, remove the debris in the reserved anchor bolt holes, and the surveying team marks the elevation and center control cross line of the bearing on the top surface of the stone;

[0128] 3) Place the support on the corresponding supporting pad stone, and the height error of the four corners of the bottom plate under the support shall not exceed 2mm;

[0129] 4) Before installing the support, check whether the support connection is normal, and do not loosen the upper and lower support connection bolts at will;

[0130] 5) Grouting shall be carried out by gravity grouting, and the gaps at the bottom of the support and the anchor holes shall be filled. Grouting shall be carried out from the center of the support to the surrounding areas until the gaps around the steel formwork and the support bottom plate are fully filled with grouting materials.

[0131] 6) Before pouring, the required slurry volume should be preliminarily calculated. The amount of slurry used for pouring should not have a large error with the calculated value, and the lack of slurry in the middle should be prevented;

[0132] 7) After the grouting material has finally set, the formwork is removed to check whether there is any leakage. If necessary, the leakage is supplemented. The surveying team re-measures the elevation and center position of the bearing. After it meets the inspection requirements, tighten the anchor bolts of the lower bearing plate;

[0133] 8) For elastically constrained multifunctional bearings, before locking the rails on the bridge, lock the elastic constraint device, remove the rubber block, and install the adjustment gaskets on both sides to keep the gap on both sides of the bearing consistent.

[0134] Specifically, the operation steps of the No. 0 block construction in step 2 include: support design and construction, support preloading and observation, formwork production and installation, steel bar binding, concrete pouring and maintenance, prestressing tensioning, and prestressed pipe grouting, a total of seven operation steps, to complete the cast-in-place operation of the No. 0 blocks at the No. 19 and No. 20 main piers;

[0135] The stent pre-compression specifically includes the following steps:

[0136] 1) Check the connection quality of the bracket and the contact surface. After the bracket is erected, carefully check whether the connection of each section of the bracket is firm and whether the welding quality of each contact surface is up to standard. After all parts are inspected and qualified, pre-compression test shall be carried out on the bracket;

[0137] 2)Stent graded pre-compression loading:

[0138] a. The preloading of the support shall be carried out in three levels: 60%, 100% and 120% of the maximum construction load that the support can bear. The distribution of the preloading load shall be consistent with the distribution of the support construction load, and the loading weight deviation shall be less than 5% of the load of the same level;

[0139] b. During the preloading process, if any abnormal situation occurs, the preloading operation should be stopped immediately, and the cause should be found out and corresponding measures should be taken to ensure the safety of the bracket before continuing the preloading operation;

[0140] c. The loading and unloading of the support preload should be carried out in accordance with the principles of symmetry, layering and grading. Concentrated loading and unloading are strictly prohibited, and the loading sequence should be carried out from the support to the mid-span. The preload operation of the bottom plate and the web plate should be carried out first, and then the preload operation of the flange plate should be carried out;

[0141] 3) Arrange measurement observation points, set up 6 monitoring sections at the top of each row of steel pipe columns and the middle span of the longitudinal beam. Each monitoring section should have 3 points symmetrically set within the range of the bottom plate, and 2 points symmetrically set at the flange plate position as observation points for bracket displacement and settlement measurement, and reserve marking points during loading;

[0142] 4) Gradual ballast and measurement observation:

[0143] a. First level loading: from 0% to 60%, the first level loading on one side of the end is 60%, and the measurement is recorded 1 hour after the loading is completed. After that, the observation is recorded every 6 hours until the difference between the average values ​​of the two adjacent observation displacements is less than 2mm, and then the next level of loading operation is carried out;

[0144] b. Second level loading: from 60% to 100%, the second level loading on one side of the end is carried out to 100%, and the measurement is recorded 1 hour after the loading is completed, and then the observation is recorded every 6 hours until the difference between the average values ​​of the two adjacent observation displacements is less than 2mm, and then the next level of loading operation is carried out;

[0145] c. The third level loading: from 100% to 120%, the third level loading on one side of the end is up to 120%, and then the observation and recording are carried out every 6 hours until the difference between the average values ​​of the displacements of two consecutive observations is less than 2mm, and then the pre-compression unloading operation is carried out. After 6 hours of unloading, the displacement of each observation point is finally observed and recorded again;

[0146] 5) Calculate the pre-camber. During the pre-loading process, measure the elastic deformation value of the support and the elastic settlement value of the foundation under the load, and superimpose this elastic deformation value with the pre-camber that needs to be set due to other factors proposed in the construction control to obtain the pre-camber that should be used during construction;

[0147] 6) Determine and adjust the bottom elevation of the beam. According to the measured support deformation value and the design elevation, determine and adjust the bottom elevation of the beam. The bottom elevation of the beam = the design bottom elevation of the beam + the elastic deformation value of the support + the design reserved camber.

[0148] The concrete pouring and curing specifically include the following steps:

[0149] 1) Pouring operation of block 0 concrete:

[0150] Carry out the pouring operation of the bottom plate concrete, starting from the bottom plate position of the pier top part, and then advancing to the bottom plate direction of the cantilever parts on both sides, until pouring to the bottom plate chamfer position, then suspend the concrete pouring operation, and confirm the filling condition of the bottom plate chamfer position through the reserved inspection hole;

[0151] b. Carry out the pouring operation of the web and diaphragm concrete. Use the multi-point feeding method to carry out the pouring operation of the web and diaphragm concrete. Move the feeding point in time during the pouring process and ensure that it is vibrated and compacted. After pouring to the chamfer position of the top plate, suspend the concrete pouring operation;

[0152] c. Carry out the pouring operation of the top plate, starting from one corner of the top plate and gradually moving to the other corner to complete the concrete pouring operation of the top plate;

[0153] 2) Concrete curing operation:

[0154] a. Before the concrete of the exposed surface protective layer begins to set, the covering material should be rolled up and the surface should be rubbed and pressed with a trowel at least twice until the concrete surface is flat and then covered again;

[0155] b. Loosen the formwork connection 24 to 48 hours after the concrete pouring is completed, and continue to water and cure the concrete until the concrete formwork is removed;

[0156] c. After the concrete is demoulded, watering or covering with water is used for wet curing of the concrete;

[0157] The specific construction steps of the prestressed pipe grouting include:

[0158] 1) Try to evacuate the vacuum, start the vacuum pump, and make the negative pressure of the system reach 0.06-0.1Mpa. When the vacuum degree in the channel remains stable, stop the vacuum pump for 1 minute. If the pressure value decreases by no more than 0.02Mpa, it means that the channel meets the vacuum requirement; if the pressure value decreases by more than 0.02Mpa, the seal of the channel needs to be checked and repaired;

[0159] 2) Mixing: First, add water to the mixer and let it run idle for several minutes before mixing the cement. When the inner wall of the mixer is fully moistened, pour out the accumulated water. Secondly, pour the weighed water into the mixer and pour the cement during the mixing process. When the cement is completely added to the mixer, continue to stir until the cement and water are evenly mixed.

[0160] 3) Pour the admixture into the mixer and continue stirring for 5 to 15 minutes, then pour the stirred cement slurry into the slurry drum;

[0161] 4) Grouting, start the vacuum pump. When the vacuum degree in the channel is maintained at a negative pressure of 0.08Mpa, open the valve, start the grouting pump, and start the grouting operation. When the slurry passes through the transparent high-pressure pipe and reaches the three-way joint, open the slurry discharge valve and close the negative pressure container valve and the vacuum pump, and observe the slurry discharge at the waste slurry barrel. If the slurry discharge is smooth and stable and the consistency is consistent with the slurry in the slurry barrel, close the grouting pump and the valve at the other end, and start the grouting pump again to make the grouting pressure value reach 0.4Mpa until the grouting operation is completed;

[0162] 5) Carry out anchor pouring operation. Before pouring anchor concrete, the tensioning groove of the beam body should be roughened first, and waterproof coating should be applied within the anchor range for waterproofing treatment.

[0163] Specifically, the operation steps of the cast-in-place section construction of the side span in step 4 include: support design and construction, support acceptance, support pre-compression, formwork production and installation, steel bar installation and binding, concrete pouring and maintenance, and support removal, a total of seven operation steps, to complete the pouring and molding of the straight section concrete of the side span of Pier 18 and Pier 21;

[0164] The specific construction steps for the support acceptance include:

[0165] 1) The position and elevation of the embedded parts of the bracket should be accurately set to meet the requirements of the pier installation accuracy. The bracket should be corrected in time during installation. The verticality deviation should be less than 1 / 500 of the pillar height, and the column top offset value should be less than 50mm;

[0166] 2) The installation of steel pipe brackets shall meet the following requirements:

[0167] a. Install in sections and layers according to the hoisting equipment and site conditions at the construction site;

[0168] b. The steel pipes and foundations and the steel pipe joints should be firmly connected, and the joint gaps should be tightly filled with steel plates;

[0169] c. The upper steel pipe can be installed only after the lower scissor brace connector is installed. Before the scissor brace is installed, temporary measures should be taken to reinforce and stabilize the steel pipe;

[0170] 3) The installation of crossbeams and longitudinal beams shall meet the following requirements:

[0171] a. Before installing the crossbeam and longitudinal beam, the installation position should be accurately marked, and the installation error should be less than 20mm;

[0172] b. After the beams are assembled into a whole, they should be hoisted into place, and the beams and pillars should be firmly connected; if there is a gap between the beams and their supports, they should be filled with steel plates and welded firmly;

[0173] c. Bailey beams and military beam truss beams should be assembled on a flat and solid site, and temporary stabilization measures should be taken;

[0174] d. The truss should be assembled into segments of one span or longer, and hoisted using a single piece or multiple pieces according to the hoisting capacity; the hoisting point should be set at a node 0.2 times the length of both ends of the truss beam. After the truss beam is in place, measures should be taken to ensure its lateral stability before loosening the hook;

[0175] e. When installing the crossbeam and longitudinal beam, the lateral bending should be strictly controlled, and the lateral bending sagitta should be less than 1 / 1000 of the span and not more than 20mm;

[0176] f. The installation of commonly used equipment for Bailey beams and military beams should comply with the relevant requirements of their user manuals.

[0177] Specifically, the removal of the bracket should meet the following requirements:

[0178] 1) When supporting and dismantling the formwork, a reliable foothold should be set up for operations at a height of more than 2m, and corresponding safety protection measures should be taken. The order of dismantling the formwork should follow the principle of supporting first and then dismantling, and dismantling the last support first, from top to bottom;

[0179] 2) Before dismantling, the support should be thoroughly inspected, all unnecessary objects should be removed, and a dismantling area should be set up to prohibit non-operating personnel from entering;

[0180] 2) The dismantling sequence is from top to bottom layer by layer. The upper and lower layers are not allowed to be dismantled at the same time. The bottom mold and bracket are easily dismantled with the help of a dismantling device;

[0181] 3) The dismantled components should be lowered from the hoist or handed down manually. Throwing is strictly prohibited. At the same time, the dismantled components should be classified and stacked in time for transportation and storage;

[0182] 4) The support will be removed after the joint section is completed and the prestressing grouting is completed. It should be carried out in a balanced and symmetrical manner in the order of erection first and then dismantling, and then erection later and then dismantling.

[0183] Specifically, the operation steps of the steel-concrete mixed section construction in step five include: on-site assembly of segments, hoisting of steel-concrete mixed sections, installation of steel bars, pouring of concrete, tensioning and grouting of prestressed steel strands, a total of five operation steps, to complete the construction of the steel-concrete mixed section.

[0184] Specifically, the operation steps of the rotation construction in step 6 include: a total of two operation steps of trial rotation and formal rotation, completing the rotation construction work of Pier 19 and Pier 20;

[0185] The specific construction steps of the trial swivel include:

[0186] 1) Preparation work before trial rotation construction:

[0187] a. Remove the support pads. Before the rotation is implemented, the sand box between the support legs and the slideway needs to be removed and the debris cleaned up;

[0188] b. Remove the waterproof and dustproof facilities between the upper and lower turntables, and remove the temporary fixing devices;

[0189] c. Slideway lubrication: Before the rotation is implemented, the slideway should be lubricated again to ensure that the resistance on the slideway is at the minimum state;

[0190] 2) Test rotation:

[0191] a. Pre-tighten the steel strands. Use a jack to pre-tighten the steel strands one by one with a force of 5 to 10KN according to the principle of first the inner layer and then the outer layer. Then reduce the pre-tightening force from 10KN to 5KN one by one, and use the jack to tighten the steel strands as a whole under oil pressure to keep the force on each steel strand of the same traction rope consistent. Finally, adopt a symmetrical pre-tightening method and repeat it several times to ensure that each steel strand is evenly stressed.

[0192] b. Turn on the power of the main console and the pump station, start the pump station, and use the main console to control the two jacks to apply force to test rotation at the same time; if it cannot rotate, use the jacks to assist in pushing out force to overcome the static friction resistance and make the bridge rotate;

[0193] c. Carry out the test of two important data, rotation speed per minute and control point operation. The rotation speed per minute is used to measure the angle of the main bridge and the horizontal chord distance of the cantilever end per minute; the control point operation is used to measure the horizontal chord distance of the cantilever end for each point movement, so as to provide an operational basis for precise positioning after the swivel is initially in place;

[0194] d. Check whether the rotating structure is balanced and stable, whether there are any faults, and whether there are cracks in the key stress-bearing parts; if there are any abnormalities, the test run should be stopped, the cause should be found out and corresponding measures should be taken to rectify the situation before continuing the test run;

[0195] e. Before the test run is about to be completed, a limit steel should be inserted between the reaction seats to prevent over-rotation. After the test run stops, a steel wedge should be inserted into the support foot to fix the ball joint;

[0196] The specific construction steps of the formal rotation include:

[0197] 1) Preparation before the formal rotation

[0198] a. Determine the center of gravity of the rotating body, weigh the rotating part with a jack, and measure its friction coefficient;

[0199] b. Clean the circular slide, check the gap between the slide and the support foot, and apply silicone grease to the front end of the support foot walkway board;

[0200] c. Calibrate the horizontal jack, auxiliary jack and fine-tuning jack;

[0201] d. Perform installation and commissioning of the horizontal swivel jack, traction rope, anchor, and pump station accessories, and ensure that each strand of steel strand is straight, without hinges or kinks;

[0202] e. Install the booster jack and reverse thrust beam;

[0203] f. Install fine-tuning and control equipment, make various measurement and control signs, and mark the position of the bridge axis;

[0204] g. Carry out inspections of key parts;

[0205] h. After the rotating body has been stationary for 24 hours, various measurement data shall be reported to the monitoring team to confirm whether it is in a balanced state;

[0206] 2) Start, tension the traction jack synchronously, and apply force in stages at 100KN per stage until the footboard moves horizontally, observe and record the static friction resistance, and then reduce the force in stages until the normal speed is no more than 0.02rad / min;

[0207] 3) Horizontal rotation: the rotation is carried out according to the rotation operation time determined by the railway department. During the horizontal rotation process, the surveying personnel need to repeatedly observe the deviation of the pier axis and the elevation change of the beam end. At the same time, ensure that the angular velocity of the rotation is not greater than 0.02rad / min, the horizontal line speed of the main beam end is not greater than 1.0m / min, and ensure stability and safety during the rotation process;

[0208] 4) Rotate at a uniform speed, and start to reduce the rotation speed when the horizontal rotation is 1.5m away from the design position; rotate horizontally to 1m away from the design position, take inching operation, and cooperate with the measurement personnel to confirm the arc length of the beam end after inching; rotate horizontally to 0.1m away from the design position, stop rotating, and measure the axis. According to the difference, accurately inching control positioning to prevent over-rotation;

[0209] 5) Positioning:

[0210] a. After the swivel is in place, accurately adjust the swivel's posture and position, and use steel wedges to lock the upper and lower turntables;

[0211] b. Use the jacks installed on the top of the temporary pier to accurately adjust the elevation of the beam end and use steel wedges to pad;

[0212] c. After the beam is fine-tuned, complete the consolidation of the upper and lower caps;

[0213] d. The rotation power system should have both automatic and manual control functions. When the end of the main beam is about to reach 1.0m before the design position, the jog operation should be adopted and close cooperation with the surveying personnel should be carried out to obtain the maximum arc length rotation data during the operation;

[0214] e. Before inching operation and precision positioning, the upper structure should be leveled;

[0215] f. Set limit piles at appropriate locations to prevent over-rotation.

[0216] Specifically, the operation steps of the side span closure and system conversion in step seven include: installation of ordinary steel bars and prestressed pipes, closure locking design, closure locking, pouring of closure section concrete, prestressing construction, hanging basket removal, system conversion, a total of seven operation steps, to complete the construction work of side span closure and system conversion. The specific operation process is:

[0217] 1) When the strength and elastic modulus of the suspended cast segment concrete reach the design values ​​and the age is not less than 7 days, install the external support of the joint segment and temporarily tension it to lock the joint support;

[0218] 2) Select the time period with the lowest temperature in a day to pour the concrete of the side span closure section beam section;

[0219] 3) After the concrete strength and elastic modulus of the joint section reach the design value, the temporary longitudinal locking of the side piers will be removed, and tensioning will be done in sequence. The temporary cables will be tensioned to the designed tonnage, and the side span supports will be removed.

[0220] Specifically, the operation steps of the steel-concrete composite beam construction in step eight include: steel beam segmentation, guide beam and steel beam segment assembly, steel beam top-pushing construction, and steel beam jointing, a total of four operation steps, to complete the construction of the steel-concrete composite beam;

[0221] The steel beam top pushing construction specifically includes the following operation steps:

[0222] 1) Preparation and inspection before pushing:

[0223] a. Check whether the joints of all valves or hard pipes on the pump station are loose, and check whether the pressure regulating spring of the overflow valve is in a completely relaxed state;

[0224] b. Check whether the cable connection between the pump station starter cabinet and the hydraulic crawler is correct;

[0225] c. Check whether the oil pipe connection between the pump station and the main oil cylinder of the hydraulic crawler is correct;

[0226] d. Power on the system and check whether the rotation direction of the hydraulic pump main shaft is correct;

[0227] e. When the pump station is not started, manually operate the corresponding buttons in the control cabinet to check whether the solenoid valve and the stop valve are operating normally, and whether the stop valve number and the crawler number correspond;

[0228] f. Check the sensor, press 2L, 2L-, L+, L- of each hydraulic crawler stroke sensor to make the corresponding signal light in the control cabinet send a signal;

[0229] e. Inspection before sliding: Start the pump station and adjust a certain pressure to extend and retract the crawler cylinder: Check whether the oil pipes of chamber A and chamber B are connected correctly; check whether the stop valve can cut off the corresponding cylinder; check whether the inverter can speed up or slow down the extension and retraction speed of the corresponding cylinder when the current changes;

[0230] f. Preload: Adjust the pressure to keep the wedge clamps in the same locking state;

[0231] 2) Start pushing the steel beam:

[0232] a. First, the crawler crane is used to complete the hoisting operation of the steel box girder segment, and the linear adjustment and the welding of the yard mouth are completed in time; secondly, after the non-destructive testing is qualified, the node repainting operation is carried out, and the interface welding operation of the guide beam and the segment is completed;

[0233] b. Carry out the first round of pushing operation and ensure the safety and stability of the beam structure during the forward pushing process;

[0234] c. Carry out the second jacking operation and continue to push forward so that the front end of the structure is supported on the top surface of the reinforced concrete box girder;

[0235] d. Perform the third jacking operation, push forward again until the jacking operation is completed, then remove the front guide beam and the rear guide beam, and install the beam drop bracket;

[0236] 3) Steel beam lowering construction: After the steel beam is pushed into place, each crane is connected into a whole by two diamond trusses through a transverse mechanism. A hydraulic lifting device is installed at the front upper crossbeam of each diamond truss, and the beam lowering operation is completed by centralized control.

[0237] Specifically, the matters needing attention during the top pushing and sliding of steel beams are as follows:

[0238] 1) After the preparation and inspection work before pushing is confirmed to be correct, formal sliding will begin;

[0239] 2) During slipping, the hydraulic crawler extension cylinder pressure is gradually increased to 20%, 40% of the required pressure, and if everything is normal, it can continue to be loaded to 60%, 80%, 90%, and 100%;

[0240] 3) When the sliding unit is about to move, stop sliding propulsion, maintain the propulsion system pressure, conduct a comprehensive inspection of the hydraulic crawler, equipment system, and structural system, and continue sliding after confirming that there is no problem with the stability and safety of the overall structure;

[0241] 4) During the hydraulic sliding process, pay attention to the pressure and load changes of the equipment system, and make careful records;

[0242] 5) Pre-set the pump source pressure value according to the designed sliding load to control the maximum output thrust of the crawler to ensure the safety of the entire sliding facility;

[0243] 6) The computer control system uses the capacitive sensor to feedback the distance signal, and controls the error of each crawler within 20mm to achieve synchronous sliding of the entire sliding unit.

[0244] Specifically, the operation steps of the bridge deck system construction in step nine include: bridge deck installation, shield installation, railing installation, column installation, beam installation, beam inner sleeve, and other auxiliary construction, a total of seven operation steps to complete the construction of the bridge deck system.

[0245] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0246] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A construction method for continuous steel-concrete combined beams of an operating line, characterized in that: The steps include: Step 1: Temporary consolidation and support construction, which provides vertical support by means of temporary anchoring, and cooperates with permanent supports to resist various unbalanced moments generated during the continuous beam segmented cantilever casting process; Step 2: Construction of Block 0, using the support as the main bearing structure, and setting up a working platform on the support to carry out subsequent template installation, steel bar binding, concrete pouring and maintenance, prestressing tendons, and prestressed pipe grouting to complete the cast-in-place operation of Block 0 of the continuous beam; Step 3: Hanging basket cantilever casting construction: hang the hanging basket as the main bearing structure on the constructed beam section, and install the formwork, steel bars, prestressed pipes, concrete pouring, prestressing tensioning and grouting of the next beam section on the hanging basket. After completing one stage of the cycle, control the hanging basket to move forward to carry out the next stage of cantilever casting until the cantilever casting operation is completed; Step 4: Construction of cast-in-place section of side span. The straight section of side span is cast in one time. During the construction, the position of anchor plate and prestressed pipe is controlled, and reserved holes and embedded parts are accurately set. Step 5: Construction of the steel-concrete mixed section: After the steel-concrete combined section is transported to the designated location by a flatbed transport vehicle, a hanging basket rear anchor, as well as a winch and a guide pulley anchor pull ring are set at the corresponding position of the bridge deck to carry out the lifting operation of the steel-concrete mixed section; Step 6: Rotation construction: the rotation beam is arranged with an integral cantilever cast-in-place beam, and the pier and beam are rotated horizontally as a whole, and the rotation construction process must be carried out within the skylight point; Step 7: Side span closure and system conversion. After the box girder is rotated and in place, the side span closure section is constructed. After the prestressing of the closure is completed, the temporary consolidation support is completely cut along the bottom of the beam and the surface of the pier top structure using a rope saw, and then broken into small pieces and lifted off. At the same time, other supporting structures on the pier top are cleaned, and the connection between the upper and lower seat plates of the permanent support is released, so that the support can slide normally, and the beam is dropped to form a single-span cantilever structure. Step 8: Construction of steel-concrete composite beams: First, use crawler cranes to complete the hoisting operation of steel box beam segments; second, perform multiple jacking operations until the jacking operation of the steel beam is completed, and remove the front guide beam and the rear guide beam, and install the beam drop bracket; finally, drop the beam as a whole, weld the joint section, and remove the beam drop bracket; Step 9: Bridge deck construction. After the steel box girder jointing operation is completed, the bridge deck crane is removed, other debris is cleaned up, the steel beam is fully inspected and local painting is completed. Then, after the prefabricated production and maintenance of the bridge deck reaches the design strength, the bridge deck construction work is carried out.

2. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of temporary consolidation and support construction in step 1 include: 1) Pre-embedded steel bars: According to the design drawings, when constructing the top section of the pier, temporary consolidation of prestressed fine-rolled threaded steel bars and pre-embedded steel bars are carried out; 2) Installation of temporary consolidation formwork: after the concrete strength of the pier reaches the design requirements, the formwork installation operation is carried out; 3) Temporary consolidation concrete pouring. To facilitate the subsequent removal of temporary supports, the height of the temporary support stop surface should be marked before concrete pouring, and a layer of sulfur mortar isolation layer should be poured on the top surface of the temporary consolidation pier before concrete pouring. 4) Bearing installation: After the bearing is in place, gravity grouting is used to carry out grouting operations between the bearing lower base plate and the supporting pad stone and in the anchor bolt hole.

3. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of the No. 0 block construction in step 2 include: support design and construction, support preloading and observation, formwork production and installation, steel bar binding, concrete pouring and maintenance, prestressing tensioning, and prestressed pipe grouting, a total of seven operation steps, to complete the cast-in-place operation of the No. 0 block; The specific construction steps of the prestressed pipe grouting include: 1) Try to evacuate the vacuum, start the vacuum pump, and make the negative pressure of the system reach 0.06-0.1Mpa. When the vacuum degree in the channel remains stable, stop the vacuum pump for 1 minute. If the pressure value decreases by no more than 0.02Mpa, it means that the channel meets the vacuum requirement; if the pressure value decreases by more than 0.02Mpa, the seal of the channel needs to be checked and repaired; 2) Mixing: First, add water to the mixer and let it run idle for several minutes before mixing the cement. When the inner wall of the mixer is fully moistened, pour out the accumulated water. Secondly, pour the weighed water into the mixer and pour the cement during the mixing process. When the cement is completely added to the mixer, continue to stir until the cement and water are evenly mixed. 3) Pour the admixture into the mixer and continue stirring for 5 to 15 minutes, then pour the stirred cement slurry into the slurry drum; 4) Grouting, start the vacuum pump. When the vacuum degree in the channel is maintained at a negative pressure of 0.08Mpa, open the valve, start the grouting pump, and start the grouting operation. When the slurry passes through the transparent high-pressure pipe and reaches the three-way joint, open the slurry discharge valve and close the negative pressure container valve and the vacuum pump, and observe the slurry discharge at the waste slurry barrel. If the slurry discharge is smooth and stable and the consistency is consistent with the slurry in the slurry barrel, close the grouting pump and the valve at the other end, and start the grouting pump again to make the grouting pressure value reach 0.4Mpa until the grouting operation is completed; 5) Carry out anchor pouring operation. Before pouring anchor concrete, the tensioning groove of the beam body should be roughened first, and waterproof coating should be applied within the anchor range for waterproofing treatment.

4. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of the cast-in-place section construction of the side span in step 4 include: support design and construction, support acceptance, support pre-compression, formwork production and installation, steel bar installation and binding, concrete pouring and maintenance, and support removal, a total of seven operation steps, to complete the pouring and molding of the side span straight section concrete; The specific construction steps for the support acceptance include: 1) The position and elevation of the embedded parts of the bracket should be accurately set to meet the requirements of the pier installation accuracy. The bracket should be corrected in time during installation. The verticality deviation should be less than 1 / 500 of the pillar height, and the column top offset value should be less than 50mm; 2) The installation of steel pipe brackets shall meet the following requirements: a. Install in sections and layers according to the hoisting equipment and site conditions at the construction site; b. The steel pipes and foundations and the steel pipe joints should be firmly connected, and the joint gaps should be tightly filled with steel plates; c. The upper steel pipe can be installed only after the lower scissor brace connector is installed. Before the scissor brace is installed, temporary measures should be taken to reinforce and stabilize the steel pipe; 3) The installation of crossbeams and longitudinal beams shall meet the following requirements: a. Before installing the crossbeam and longitudinal beam, the installation position should be accurately marked, and the installation error should be less than 20mm; b. After the beams are assembled into a whole, they should be hoisted into place, and the beams and pillars should be firmly connected; if there is a gap between the beams and their supports, they should be filled with steel plates and welded firmly; c. Bailey beams and military beam truss beams should be assembled on a flat and solid site, and temporary stabilization measures should be taken; d. The truss should be assembled into segments of one span or longer, and hoisted using a single piece or multiple pieces according to the hoisting capacity; the hoisting point should be set at a node 0.2 times the length of both ends of the truss beam. After the truss beam is in place, measures should be taken to ensure its lateral stability before loosening the hook; e. When installing the crossbeam and longitudinal beam, the lateral bending should be strictly controlled, and the lateral bending sagitta should be less than 1 / 1000 of the span and not more than 20mm; f. The installation of commonly used equipment for Bailey beams and military beams should comply with the relevant requirements of their user manuals.

5. The method for constructing a continuous steel-concrete combined beam for an operating line according to claim 1, characterized in that: The operation steps of the steel-concrete mixed section construction in step five include: on-site assembly of segments, hoisting of steel-concrete mixed sections, installation of steel bars, pouring of concrete, tensioning and grouting of prestressed steel strands, a total of five operation steps, to complete the construction of the steel-concrete mixed section.

6. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of the rotating body construction in step 6 include: a total of two operation steps of trial rotating body and formal rotating body, and the construction work of the rotating body is completed; The specific construction steps of the trial swivel include: 1) Preparation work before trial rotation construction: a. Remove the support pads. Before the rotation is implemented, the sand box between the support legs and the slideway needs to be removed and the debris cleaned up; b. Remove the waterproof and dustproof facilities between the upper and lower turntables, and remove the temporary fixing devices; c. Slideway lubrication: Before the rotation is implemented, the slideway should be lubricated again to ensure that the resistance on the slideway is at the minimum state; 2) Test rotation: a. Pre-tighten the steel strands. Use a jack to pre-tighten the steel strands one by one with a force of 5 to 10KN according to the principle of first the inner layer and then the outer layer. Then reduce the pre-tightening force from 10KN to 5KN one by one, and use the jack to tighten the steel strands as a whole under oil pressure to keep the force on each steel strand of the same traction rope consistent. Finally, adopt a symmetrical pre-tightening method and repeat it several times to ensure that each steel strand is evenly stressed. b. Turn on the power of the main console and the pump station, start the pump station, and use the main console to control the two jacks to apply force to test rotation at the same time; if it cannot rotate, use the jacks to assist in pushing out force to overcome the static friction resistance and make the bridge rotate; c. Carry out the test of two important data, rotation speed per minute and control point operation. The rotation speed per minute is used to measure the angle of the main bridge and the horizontal chord distance of the cantilever end per minute; the control point operation is used to measure the horizontal chord distance of the cantilever end for each point movement, so as to provide an operational basis for precise positioning after the swivel is initially in place; d. Check whether the rotating structure is balanced and stable, whether there are any faults, and whether there are cracks in the key stress-bearing parts; if there are any abnormalities, the test run should be stopped, the cause should be found out and corresponding measures should be taken to rectify the situation before continuing the test run; e. Before the test run is about to be completed, a limit steel should be inserted between the reaction seats to prevent over-rotation. After the test run stops, a steel wedge should be inserted into the support foot to fix the ball joint; The specific construction steps of the formal rotation include: 1) Preparation before the formal rotation a. Determine the center of gravity of the rotating body, weigh the rotating part with a jack, and measure its friction coefficient; b. Clean the circular slide, check the gap between the slide and the support foot, and apply silicone grease to the front end of the support foot walkway board; c. Calibrate the horizontal jack, auxiliary jack and fine-tuning jack; d. Perform installation and commissioning of the horizontal swivel jack, traction rope, anchor, and pump station accessories, and ensure that each strand of steel strand is straight, without hinges or kinks; e. Install the booster jack and reverse thrust beam; f. Install fine-tuning and control equipment, make various measurement and control signs, and mark the position of the bridge axis; g. Carry out inspection operations on key parts; h. After the rotating body has been stationary for 24 hours, various measurement data shall be reported to the monitoring team to confirm whether it is in a balanced state; 2) Start, tension the traction jack synchronously, and apply force in stages at 100KN per stage until the footboard moves horizontally, observe and record the static friction resistance, and then reduce the force in stages until the normal speed is no more than 0.02rad / min; 3) Horizontal rotation: the rotation is carried out according to the rotation operation time determined by the railway department. During the horizontal rotation process, the surveying personnel need to repeatedly observe the deviation of the pier axis and the elevation change of the beam end. At the same time, ensure that the angular velocity of the rotation is not greater than 0.02rad / min, the horizontal line speed of the main beam end is not greater than 1.0m / min, and ensure stability and safety during the rotation process; 4) Rotate at a uniform speed, and start to reduce the rotation speed when the horizontal rotation is 1.5m away from the design position; rotate horizontally to 1m away from the design position, take inching operation, and cooperate with the measurement personnel to confirm the arc length of the beam end after inching; rotate horizontally to 0.1m away from the design position, stop rotating, and measure the axis. According to the difference, accurately inching control positioning to prevent over-rotation; 5) Positioning: a. After the swivel is in place, accurately adjust the swivel's posture and position, and use steel wedges to lock the upper and lower turntables; b. Use the jacks installed on the top of the temporary pier to accurately adjust the elevation of the beam end and use steel wedges to pad; c. After the beam is fine-tuned, complete the consolidation of the upper and lower caps; d. The rotation power system should have both automatic and manual control functions. When the end of the main beam is about to reach 1.0m before the design position, the jog operation should be adopted and close cooperation with the surveying personnel should be carried out to obtain the maximum arc length rotation data during the operation; e. Before inching operation and precision positioning, the upper structure should be leveled; f. Set limit piles at appropriate locations to prevent over-rotation.

7. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of side span closure and system conversion in step seven include: installation of common steel bars and prestressed pipes, closure locking design, closure locking, pouring of closure section concrete, prestressing construction, hanging basket removal, system conversion, a total of seven operation steps, to complete the construction work of side span closure and system conversion, the specific operation process is: 1) When the strength and elastic modulus of the suspended cast segment concrete reach the design values ​​and the age is not less than 7 days, install the external support of the joint segment and temporarily tension it to lock the joint support; 2) Select the time period with the lowest temperature in a day to pour the concrete of the side span closure section beam section; 3) After the concrete strength and elastic modulus of the joint section reach the design value, the temporary longitudinal locking of the side piers will be removed, and tensioning will be done in sequence. The temporary cables will be tensioned to the designed tonnage, and the side span supports will be removed.

8. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of the steel-concrete composite beam construction in step eight include: steel beam segmentation, guide beam and steel beam segment assembly, steel beam top-pushing construction, and steel beam jointing, thus completing the construction of the steel-concrete composite beam; The steel beam top pushing construction specifically includes the following operation steps: 1) Preparation and inspection before pushing: a. Check whether the joints of all valves or hard pipes on the pump station are loose, and check whether the pressure regulating spring of the overflow valve is in a completely relaxed state; b. Check whether the cable connection between the pump station starter cabinet and the hydraulic crawler is correct; c. Check whether the oil pipe connection between the pump station and the main oil cylinder of the hydraulic crawler is correct; d. Power on the system and check whether the rotation direction of the hydraulic pump main shaft is correct; e. When the pump station is not started, manually operate the corresponding buttons in the control cabinet to check whether the solenoid valve and the stop valve are operating normally, and whether the stop valve number and the crawler number correspond; f. Check the sensor, press 2L, 2L-, L+, L- of each hydraulic crawler stroke sensor to make the corresponding signal light in the control cabinet send a signal; e. Inspection before sliding: Start the pump station and adjust a certain pressure to extend and retract the crawler cylinder: Check whether the oil pipes of chamber A and chamber B are connected correctly; check whether the stop valve can cut off the corresponding cylinder; check whether the inverter can speed up or slow down the extension and retraction speed of the corresponding cylinder when the current changes; f. Preload: Adjust the pressure to keep the wedge clamps in the same locking state; 2) Start pushing the steel beam: a. First, the crawler crane is used to complete the hoisting operation of the steel box girder segment, and the linear adjustment and the welding of the yard mouth are completed in time; secondly, after the non-destructive testing is qualified, the node repainting operation is carried out, and the interface welding operation of the guide beam and the segment is completed; b. Carry out the first round of pushing operation and ensure the safety and stability of the beam structure during the forward pushing process; c. Carry out the second jacking operation and continue to push forward so that the front end of the structure is supported on the top surface of the reinforced concrete box girder; d. Perform the third jacking operation, push forward again until the jacking operation is completed, then remove the front guide beam and the rear guide beam, and install the beam drop bracket; 3) Steel beam lowering construction: After the steel beam is pushed into place, each crane is connected into a whole by two diamond trusses through a transverse mechanism. A hydraulic lifting device is installed at the front upper crossbeam of each diamond truss, and the beam lowering operation is completed by centralized control.

9. The method for constructing a continuous steel-concrete composite beam for an operating line according to claim 1, characterized in that: The operation steps of the bridge deck system construction in step nine include: bridge deck installation, shield installation, railing installation, column installation, beam installation, beam inner sleeve, and other auxiliary construction, a total of seven operation steps to complete the construction of the bridge deck system.

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