CN111926705A - Method for integrally assembling ultra-wide framing steel box girder - Google Patents

Abstract

The invention discloses an overall assembling method of an ultra-wide framing steel box girder, and relates to the technical field of steel box girder assembling. The method comprises the steps of manufacturing plate units, assembling and welding plates, matching and assembling and welding beam sections, pre-assembling and pre-assembling, and inspecting the beam sections, wherein the beam sections are assembled and welded in a three-dimensional stepped propelling mode section by section according to the sequence of a bottom plate, a diaphragm plate, a middle top plate, a primary positioning inner web plate, an anchor web plate, other top plates, a secondary positioning anchor web plate, a middle cross beam and a cantilever arm block body; the influence of the shrinkage of the welding circular seam and the beam section compression caused by the cable force on the length needs to be considered during pre-assembly, and the accumulated total length and the error of the previous pre-assembly are suitable to be corrected in the next assembly. The invention has the advantages that: the amount of butt welding seams of the steel box girder on the total assembly jig frame can be reduced, and the manufacturing period is shortened; the three-dimensional stepped propulsion mode is assembled and welded section by section and then is pre-assembled, and the overall dimension is easy to control; the assembling precision of the steel box girder can be ensured, the assembling quality is controlled, the adjustment at high altitude is avoided, and the erection period is shortened.

Description

Method for integrally assembling ultra-wide framing steel box girder

Technical Field

The invention relates to the technical field of steel box girder assembly, in particular to an integral assembly method of an ultra-wide framing steel box girder.

Background

The steel box girder is also called steel plate box girder, and is a common structural form of a large-span bridge. In a large-span cable support bridge, the span of a steel box girder reaches hundreds of meters and up to thousands of meters, the steel box girder is generally manufactured and installed by a plurality of beam sections, the cross section of the steel box girder has the characteristics of wide width and flat appearance, and the height-to-width ratio reaches about 1: 10. The steel box girder is generally formed by connecting a top plate, a bottom plate, a web plate, a transverse clapboard, a longitudinal clapboard, a stiffening rib and the like in a full-welding mode.

In the prior art, a transverse multi-section dividing and assembling method for an ultra-wide steel box girder with application number 201811603613.9 is disclosed, two processes of multi-section continuous matching manufacturing and pre-assembling are adopted, and through the matching of an assembling jig frame and a measurement control network, the linear manufacturing of the assembling jig frame and the assembling of the girder section are based on the preset measurement control network, so that the assembling linearity and the interface precision of the steel box girder are ensured, and the assembling precision of the steel box girder can be well controlled.

However, the assembly method can cause long manufacturing period of the steel box girder, the external dimension is not easy to control, and a 'long-line method' assembly scheme that multi-section continuous matching manufacturing and pre-assembly are simultaneously completed is adopted, the influence of beam section compression caused by welding circular seam shrinkage and cable force on the length is difficult to correct, the correction difficulty is large, the assembly precision of the steel box girder is influenced, the assembly quality is not easy to control, the steel box girder is directly erected after the pre-assembly, when the beam section dimension is found to be wrong or the pre-camber is not consistent during erection, adjustment needs to be carried out at high altitude, the high altitude operation difficulty is large, the erection period is long, and the construction efficiency is low.

Disclosure of Invention

The technical problem to be solved by the invention is to provide an ultra-wide framing steel box girder integral assembling method which can shorten the manufacturing period, is pre-assembled after being assembled by welding section by section in a three-dimensional stepped propelling mode, is easy to control the appearance size, ensures the assembling precision of the steel box girder, avoids the adjustment at high altitude, reduces the difficulty of high altitude operation, accelerates the hoisting speed, shortens the erection period and has high construction efficiency.

In order to solve the technical problems, the technical scheme of the invention is as follows: the method comprises the following steps of manufacturing plate units, assembling and welding plates, matching and assembling and welding beam sections, pre-assembling and pre-assembling inspection, wherein the pre-assembling and welding are completed at one time, and the method comprises the following specific steps:

s1, manufacturing a plate unit and assembling and welding a plate block:

s1.1, after sampling the steel plate, leveling and preprocessing the steel plate, and then carrying out corresponding processing;

s1.2, plate assembly welding: before the plate units participate in the assembly of the beam sections, the plate units are firstly spliced and welded on a special jig frame to form a hoisting plate block, the center distance of adjacent U-shaped stiffening ribs on two sides of a welding line is controlled by using a sample plate with a reserved welding shrinkage amount during splicing, reverse deformation is preset, and after the two-stage splicing of the plate units is completed, the plate units are turned over by using an integral lifting appliance which is in the form of an integral carrying pole and is provided with 3-5 lifting points;

s2, matching, assembling and welding beam sections: in the manufacturing of the box girder section, assembling and welding section by section in a three-dimensional stepped propelling mode on a total assembly jig frame according to the sequence of a bottom plate, a diaphragm plate, a middle top plate, a primary positioning inner web plate, an anchor web plate, other top plates, a secondary positioning anchor web plate, a middle cross beam and a cantilever arm block body;

s3, pre-assembling: matching and assembling a plurality of beam sections, reserving gaps according to a manufacturing line shape and beam sections to match connecting sections of adjacent beam sections, welding seams, cutting back tower ends according to the manufacturing length after welding, considering the influence of beam section compression caused by welding circular seam shrinkage and cable force on the length during pre-assembling, correcting the accumulated total length and error of the last pre-assembling in the next assembling, accurately adjusting and measuring the line shape, the length, the port size and the straightness, marking the beam section number after each round of pre-assembling is qualified, leaving the last beam section to participate in the next round of pre-assembling, leaving the rest beam sections to enter a coating process, removing the constraint with a bottom tire frame code plate when pre-assembling with a main beam, enabling the beam sections to be in a free state, enabling the pre-assembling sequence to be the same as the beam section hoisting sequence, and not changing the beam section number during hoisting; limited by the width of the coating room, and after the box girder segment is coated, the cantilever block is accurately assembled and positioned;

s4, pre-assembly inspection: and (3) directly performing pre-assembly inspection on the total assembly jig frame after the whole assembly welding and pre-assembly of each wheel beam section are finished, and performing key inspection: the method comprises the steps of bridge longitudinal line shape, beam section longitudinal accumulated length, full-bridge pre-splicing camber, box beam axis central line deviation, transverse slope, distortion and checking the matching condition of the end faces of adjacent sections.

Furthermore, the total assembly jig frame in the step 2 is provided with longitudinal and transverse datum lines, datum points and a bridge center line for positioning the bottom plate unit, a measuring mark tower is arranged at each end of the total assembly jig frame, datum mark lines are arranged on the towers according to process data and are used as independent measuring nets outside the jig frame to detect the jig frame at any time, the total assembly jig frame is provided with tooth plates according to a manufacturing line type, and pre-camber is transversely arranged.

Further, in the step S2, the assembling adopts a positive assembling method, the jig frame is used as an outer tire, the diaphragm plate is used as an inner tire, each plate unit is positioned according to the longitudinal and transverse base lines, and a reinforcing facility is used for ensuring the precision and the safety;

bottom plate, cross slab, middle roof, primary location inner web and anchor web, all the other roofs, secondary location anchor web, middle cross beam, the equipment and the welding of the block of the arm of picking are as follows:

s2.1, assembling and welding a bottom plate and a pressure heavy groove of a beam section of a pressure heavy area: firstly, placing a middle bottom plate unit on a total assembly jig frame, positioning by using a theodolite, accurately aligning a transverse base line and a longitudinal base line of the middle bottom plate unit with the base lines on the jig frame under the condition of no sunshine influence, fixing the middle bottom plate unit with the total assembly jig frame, assembling and positioning bottom plates on two sides, then assembling and positioning an inclined bottom plate with the bottom plates according to a web positioning line on the jig frame, welding butt welding seams between a flat bottom plate and the inclined bottom plates, and positioning and assembling a ballast tank after assembling and positioning a beam section flat bottom plate with the ballast tank;

s2.2, assembling and welding diaphragm plate units and reinforcing angular points: using a longitudinal base line on a bottom plate as a reference, positioning the transverse position of a transverse clapboard by using a theodolite, welding a transverse clapboard landing horse plate on the bottom plate, and positioning the transverse base line position of the transverse clapboard by using a leveling instrument so as to determine the height position of the transverse clapboard; all the partition plates are vertically arranged in a bridge state, so that after the arrangement of each partition plate is finished, the angle of the partition plate needs to be adjusted by using a line vertical mode, the slope of the upper edge of the transverse partition plate and the verticality between the transverse partition plate and the bottom plate are well adjusted and controlled, the transverse partition plate is fixed by using a temporary fixing jig, the inner transverse partition plate is assembled firstly during assembly, and then the outer transverse partition plate is assembled, so that the groove mouth of the U rib is ensured not to conflict with the U rib;

s2.3, assembling a middle top plate unit: the integral assembly of the steel box girder top plate is carried out in a step sequence from the left center to the right center to the two sides of the steel box girder top plate respectively from a positioning end, the central top plate unit is positioned, the central top plate is positioned by a theodolite by taking a marking line of a marking tower as a reference according to a longitudinal base line of the top plate, and the transverse direction is positioned by the theodolite and a plumb bob method by taking a transverse base line of the top plate as a reference;

s2.4, primary positioning and assembling of the inner web plate and the anchor web plate unit: the lower edge of the outer anchor web plate is based on an assembly line placed on the inclined bottom plate during transverse positioning, the upper edge of the outer anchor web plate is based on a positioning mark line, a transverse base line placed on the central top plate is based on longitudinal positioning, and meanwhile, theodolites are used for correcting relative dislocation of the upper and lower inner anchor web plates and the outer anchor web plates, and the outer anchor web plates are fixed after no error is confirmed;

s2.5, assembling the rest top plate units: assembling top plate blocks from the middle to two sides, welding longitudinal butt welds, accurately positioning plate unit elements of the top plate at the central line of each section of box girder by using a theodolite, and welding a corner groove weld at an outer web plate, wherein the plate unit elements and the central reference line of the bottom plate are positioned on the same vertical plane;

s2.6, secondary positioning of an anchor web: before assembling the side top plate, when the influence of the temperature on the size of the steel plate is small, the theodolite is reused to accurately adjust the anchor web plate by taking a mark line on the mark tower as a reference, welding shrinkage is reserved during adjustment to ensure the half-width size of the steel box girder after the anchor web plate and the diaphragm plate are welded, and then the welding of the web plate and the diaphragm plate as well as the diaphragm plate and the inclined bottom plate is completed;

s2.7, assembling and positioning the middle cross beam: after secondary positioning of the anchor web is completed, before the top plate at the most lateral side is laid, the position line of the partition plate is returned to the outer side of the inner web to serve as a web plate positioning reference of the middle cross beam, the middle cross beam is positioned and assembled by a crane, after the first section of the steel box beam is installed, a jig at the inclined strut position is removed, the bottom plate of the cross beam is hoisted firstly, after the positioning is completed, the assembly is performed according to the sequence of the partition plate, the web plate and the top plate, and each cross beam of each turn is performed after the section is installed;

s2.8, assembling and positioning cantilever arm blocks: before assembling the outermost top plate unit, the position line of the partition plate is returned to the outer side of the outer web plate to serve as a reference for accurately positioning the relative position of the cantilever block body and the transverse partition plate, the cantilever is positioned by taking the position line of the partition plate on the outer side of the outer web plate as the reference, the cantilever block body and the web plate are fixed, a positioning reference line is made after positioning is completed, and a temporary matching piece is installed between the cantilever block bodies.

Further, in the step S3, the pre-assembly is performed by taking the first batch of steel box girders as test girder segments, comprehensively checking whether the whole manufacturing process is reasonable and whether the production measures are proper, and performing batch production after confirmation; according to the accumulated total length and errors after the last pre-assembly, the length of the next pre-assembled beam section is corrected, and the error accumulation is avoided; matching and finishing adjacent ports during pre-assembly; and reserving a trimming allowance for the length of the folded section.

Further, in the step S4, during the pre-assembly inspection and measurement, the elevation and the length of each beam section are measured, so as to avoid the influence of sunlight and record the ambient temperature; preparing before measurement, accelerating the adjustment speed so as to weaken the influence of the jack settlement on the elevation of the matched beam section, storing a steel belt or a standard ruler for measurement under the same condition with a detected workpiece before use, keeping the temperature of the steel belt or the standard ruler consistent with that of the detected workpiece, and periodically detecting the steel belt or the standard ruler;

before the two-wheel connecting beam sections are matched, all horse boards connected with the bottom plate and the jig frame are unfastened, matching and butt joint are carried out in an unconstrained state, and two box beams and two cross beams are associated to be carried out during assembling and positioning so as to ensure the matching property between the box beams and the cross beams.

Further, in the step S1.2, during the plate assembly welding, when the plate units are assembled in two, the misalignment amount of the bevel end of the two plate units is controlled to be less than or equal to 1mm according to the linear assembly of the longitudinal baseline and the transverse baseline of the plate units, the relative deviation of the connecting plate of the transverse partition plate of the top plate is controlled to be less than or equal to 2mm, the unevenness of four corners is less than or equal to 5mm, the diagonal difference is less than or equal to 4mm, 30-35mm upward reverse deformation is preset at the welding seam when the plate units are assembled in two, the flame trimming amount is reduced, and the; for transverse positioning, welding shrinkage of 2-3mm is reserved in the width direction of the plate unit.

Furthermore, in the step S2.1, the bottom plate unit is positioned, the longitudinal base lines on both sides of the central line of the central bottom plate unit of the beam section are taken as references, and are used as a positioning and checking line in the direction of the central line of the box girder, the bottom plate at the central line is adjusted, so that the marks at both ends of the bottom plate unit coincide with the straight line where the theodolite is located, the bottom plate is fixed after adjustment, the central bottom plate is ensured not to be displaced, and the positioning of all the bottom plate units on the central line is sequentially completed according to the;

positioning the bottom plate units on two sides, measuring the distance between longitudinal baselines of two adjacent plates by using a disc ruler, adding 2-3mm welding shrinkage, erecting and adjusting a theodolite at the intersection point of the transverse baselines and the longitudinal baselines on the central bottom plate to enable the theodolite to be collinear with the marker line on the central marker tower, adjusting the plates to enable the end measuring and inspecting line to be superposed with a theodolite control straight line, wherein the misalignment amount of the slope ends of the adjacent plate units is less than or equal to 1mm, and the relative deviation of the cross partition plate connecting plates is less than or equal to 2mm, and sequentially completing the transverse;

assembling and positioning the inner inclined bottom plate and the outer inclined bottom plate, and adjusting the inclined bottom plate to ensure that a longitudinal baseline of the inclined bottom plate is superposed with a control line, wherein the deviation is +2.5 +/-0.5 mm and contains welding shrinkage;

checking a bottom plate stopping point: and after the welding and repairing of the whole round bottom plate and the inclined bottom plate group are finished, carrying out bottom plate elevation inspection, determining that the deviation is qualified if the deviation is not more than +/-2 mm, otherwise, adjusting the bottom plate unit until the elevation is qualified, and taking the inner and outer web positioning mark lines as reference lines after all the welding and repairing of each round beam section are finished as datum lines of assembling and positioning anchor webs to obtain the web positioning net.

Further, in the steps S2 and S3, the middle roof plate unit is positioned, the roof plate units on both sides of the center line are positioned by drawing a transverse positioning inspection line from the longitudinal base line of the two roof plate splicing units close to the beam side to the center side of the beam section with the beam section center line as a reference, the return line distance is 1000mm, and the deviation is 1 mm; longitudinally positioning, namely adjusting the deviation by 2mm by using a method of measuring and checking a line plumb bob of a line with a bottom plate, transversely positioning, adjusting a top plate by using a theodolite to enable the theodolite to be coincident with the central line of an upper beam section of the marking tower, enabling a laser point of the theodolite to be coincident with the transverse positioning and checking line of the top plate, and determining the elevation of each measuring point of the top plate by using a leveling instrument according to the elevation of a measuring point of the top plate after viewpoint back calculation so as to ensure the linear;

further, in the steps S2 and S7, the middle beam bottom plate is positioned and assembled, firstly, a straight line where the transverse center line of the beam bottom plate is located is found by using a steel disc ruler with a U-rib assembly reference line on the central bottom plate as a reference, an instrument is erected at the intersection point of the longitudinal base line of the central bottom plate and the transverse center line of the beam bottom plate, the instrument is adjusted to be collinear with the central marker tower and then rotated by 90 degrees, the central line of the bridge and the central marker tower are combined to assemble and position the middle beam bottom plate, the central deviation is fixed after positioning, the central deviation is 0.5mm, and 2-3mm is pushed to the middle beam side more when the side beam bottom plate is assembled to serve as the shrinkage of the;

assembling the web plate, the partition plate and the top plate of the middle cross beam, adjusting the elevation of a bottom plate of the cross beam, controlling the position elevation deviation of the partition plate to be less than or equal to 2mm, accurately assembling the cross beam partition plate according to the transverse and longitudinal base lines, adjusting the verticality deviation of the partition plate to be less than or equal to 2mm, assembling the web plate by taking the partition plate as an inner tube after welding, finally assembling the top plate, and ensuring that the centers of all cross beams in one turn.

The invention has the advantages that: the top plate unit is welded on the special jig frame to form a hoisting plate, so that the amount of butt welding seams of the steel box beam on the total assembling jig frame can be reduced, and the manufacturing period is shortened;

sequentially assembling and welding according to the procedures of primary positioning of a bottom plate, a diaphragm plate, a middle top plate, an inner web plate and an anchor web plate, secondary positioning of the rest top plates, the anchor web plates, a middle cross beam and a cantilever block body, assembling and pre-assembling after section-by-section assembling and welding in a three-dimensional stepped propulsion mode, and easily controlling the overall dimension;

the beam section assembly welding and the pre-assembly are completed on the jig frame at one time, after each round of pre-assembly, the beam section number is marked, the last beam section is left to participate in the next round of pre-assembly, other beam sections are discharged from the jig to enter a coating process, the influence of the beam section compression caused by the welding circular seam shrinkage and the cable force on the length can be considered during the pre-assembly, the accumulated total length and the error of the last pre-assembly can be corrected in the next assembly, the inspection is carried out after the pre-assembly, the assembly precision of the steel box beam is ensured, the assembly quality is controlled, the adjustment at high altitude is avoided, the high altitude operation difficulty is reduced, the hoisting speed is accelerated, the erection period is shortened, and the construction efficiency is high.

Drawings

FIG. 1 is a side view of the overall jig assembly of the present invention;

FIG. 2 is a schematic view of the overall structure of the overall jig-splicing frame of the present invention;

FIG. 3 is an assembled view of the diaphragm of the present invention;

FIG. 4 is an assembled schematic view of the intermediate ceiling unit of the present invention;

FIG. 5 is an assembled schematic view of the inner web, anchor web of the present invention;

FIG. 6 is an assembled schematic view of the remaining ceiling elements of the present invention;

FIG. 7 is an assembled schematic view of the center sill of the present invention;

FIG. 8 is an assembled view of the cantilever block of the present invention;

FIG. 9 is a schematic view of a base measurement line and a bed base of the present invention;

FIG. 10 is a schematic view of a single box girder test point arrangement of the present invention;

fig. 11 is a schematic view of the field test by the measurement control network of the jig frame region in the pre-assembly of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and the detailed description. The following examples are presented to enable one of ordinary skill in the art to more fully understand the present invention and are not intended to limit the scope of the embodiments described herein.

The specific implementation mode adopts the following technical scheme: the method comprises the following steps of manufacturing plate units, assembling and welding plates, matching and assembling and welding beam sections, pre-assembling and pre-assembling inspection, wherein the pre-assembling and welding are completed at one time, and the method comprises the following specific steps:

s1, manufacturing a plate unit and assembling and welding a plate block:

s1.1, after sampling the steel plate, leveling and preprocessing the steel plate, and then carrying out corresponding processing;

s1.2, plate assembly welding: before the top and bottom plate units participate in the assembly of the beam sections, two or three top and bottom plate units are firstly spliced into a hoisting plate on a special jig, the center distance of adjacent U-shaped stiffening ribs on two sides of a welding line is controlled by using a sample plate with reserved welding shrinkage during splicing, and the pre-deformation is 30-35mm so as to ensure the dimensional accuracy and the flatness of the welded plate. By adopting the scheme, the welding seam amount which needs to be butted on the total assembling jig frame can be reduced by half, the manufacturing period can be shortened, the overall dimension of the steel box girder is easy to control, after the two assembling of the plate units are completed, the plate units are turned over by using the integral lifting appliance, the integral lifting appliance is in the form of an integral carrying pole and is provided with 3-5 lifting points, so that the deformation of the plate units is avoided.

When two plate units are spliced, the longitudinal and transverse baselines of the plate units are paired according to lines, and key control is performed: the misalignment amount of the slope ends of the two plate units is less than or equal to 1mm, the relative deviation of the connecting plates of the transverse partition plates of the top plate is less than or equal to 2mm,

the unevenness of four corners is less than or equal to 5mm, and the diagonal difference is less than or equal to 4 mm. In order to reduce welding deformation, 20-30 mm upward reverse deformation amount (which can be adjusted according to actual conditions) is preset at a welding seam when the two plate units are spliced so as to reduce flame trimming amount and ensure the flatness of the plate units, and 2-3mm welding shrinkage amount (which can be adjusted according to actual conditions) is reserved in the width direction of the plate units for transverse positioning.

S2, matching, assembling and welding beam sections: in the manufacturing of the box girder section, assembling and welding section by section in a three-dimensional stepped propelling mode on a total assembly jig frame according to the sequence of a bottom plate, a diaphragm plate, a middle top plate, a primary positioning inner web plate, an anchor web plate, other top plates, a secondary positioning anchor web plate, a middle cross beam and a cantilever arm block body; during assembly, the tire frame is used as an outer tire, the diaphragm plate is used as an inner tire, and the line shape of the bridge, the geometric shape and the dimensional accuracy of the steel box girder, the accurate matching of adjacent interfaces, the accuracy of the bridge cross slope and the like are controlled in a key mode.

As shown in fig. 1 and 2, the design of the total assembly jig frame should meet the special technical specification requirements of the project, the jig frame must have the longitudinal and transverse datum lines, datum points and the bridge center line for positioning the bottom plate unit, 7 measurement mark towers are arranged at each head of the jig frame, the datum mark lines are arranged on the towers according to process data and used as independent measurement nets outside the jig frame for detecting the jig frame at any time, the total assembly jig frame arranges tooth plates according to the manufacturing line type provided by a monitoring unit, and the pre-camber is transversely arranged.

S2.1, assembling and welding a bottom plate and a pressure heavy groove of a beam section of a pressure heavy area: firstly, a middle bottom plate unit is arranged on a jig frame and is positioned by a theodolite, so that the transverse base line and the longitudinal base line of the middle bottom plate unit are accurately aligned with the base lines on the jig frame under the condition of no sunlight influence and are fixed with the jig frame; assembling and positioning the bottom plates at the two sides, welding longitudinal butt-joint welding seams among the plate unit pieces by adopting ceramic liner single-side CO2, continuously welding from one end to the other end, and simultaneously and symmetrically welding from the central plate unit piece to the two sides; and then assembling and positioning the inclined bottom plate and the bottom plate according to a web plate positioning line on the jig frame, and welding a butt welding seam between the flat bottom plate and the inclined bottom plate. After the beam section flat base plate that has the ballast tank is assembled and positioned, the ballast tank is assembled and positioned in a positioning manner, and the ballast tank is positioned by taking the hole as a reference when being connected, so that the ballast base plate is ensured to be smoothly connected with the vertical plate, and the flat base plate finish paint can not be damaged by attention during the assembly of the ballast tank.

Positioning and measuring the bottom plate unit, taking longitudinal base lines on two sides of the central line of the bottom plate unit in the center of the beam section as a reference, and taking the longitudinal base lines as a positioning and checking line of the central line direction of the box beam, wherein the allowable deviation is +/-0.5 mm; adjusting the bottom plate at the central line to enable the marks at the two ends of the bottom plate unit to coincide with the straight line where the theodolite is located, wherein the deviation of the alignment is +/-0.5 mm, and after the adjustment is finished, fixing the bottom plate by using a rigid code to ensure that the central bottom plate does not displace; and sequentially finishing the positioning of all the bottom plate units on the central line according to the given longitudinal distance of the transverse base line of the bottom plate, wherein the deviation of the full-length straightness is allowed to be 1 mm. And (4) after the welding of the bottom plates at the central lines of all the beam sections in the whole round is finished, re-lofting the central lines of the beam sections, and marking the central lines to be used as reference lines for positioning the longitudinal steel drawing rulers of other bottom plate units.

The two side bottom plate units are positioned and measured, the distance between the longitudinal baselines of two adjacent plates is measured by a disc ruler, 2-3mm welding shrinkage is added, a theodolite is erected and adjusted at the intersection point of the transverse baselines and the longitudinal baselines on the central bottom plate to be collinear with the corresponding position marker lines on the central marker tower, the plate is adjusted to enable the end measuring and inspecting line to coincide with a theodolite control straight line, the misalignment amount of the bevel ends of the adjacent plate units is less than or equal to 1mm, the relative deviation of the connecting plates of the transverse partition plates is less than or equal to 2mm, the transverse and longitudinal positioning of the bottom plate units is completed in.

Assembling and positioning the inner inclined bottom plate and the outer inclined bottom plate, and adjusting the inclined bottom plate to ensure that a longitudinal baseline of the inclined bottom plate is superposed with a control line, wherein the allowable deviation is +2.5 +/-0.5 mm (including welding shrinkage); and the other station carries out longitudinal positioning, and the longitudinal positioning method is the same as that of the bottom plate unit.

And (3) checking stop points of the base plates, after the welding and repairing of the base plates and the inclined base plate groups of the whole round are completed, carrying out elevation inspection on the base plates, if the deviation is not more than +/-2 mm, determining that the base plates are qualified, otherwise, adjusting the base plate units until the elevation is qualified, and taking the inner web plate positioning mark line and the outer web plate positioning mark line as reference lines after all welding and repairing of the beam sections of each round are completed as assembly positioning anchor web plates to obtain a web plate positioning net.

S2.2, assembling and welding diaphragm plate units and reinforcing angular points: taking a vertical base line on the bottom plate as a reference, and positioning the transverse position of the transverse clapboard by using a theodolite so that the deviation between the vertical base line of the transverse clapboard and the transverse base line of the bottom plate is controlled within the range of 0.5 mm; welding a diaphragm plate falling horse plate on the bottom plate, and positioning the transverse base line position of the diaphragm plate by using a leveling instrument to determine the height position of the diaphragm plate; note that all the partition boards are arranged in a vertical manner in a bridge state, so that after each partition board is arranged, the angle of the partition board needs to be adjusted by using a vertical line; adjusting and controlling the slope of the upper edge of the diaphragm plate and the verticality between the diaphragm plate and the bottom plate, and fixing the diaphragm plate by using a temporary fixing jig; during assembly, the inner diaphragm plate is assembled first, and then the outer diaphragm plate is assembled, so that the notches of the U-shaped ribs and the U-shaped ribs are ensured not to collide, as shown in FIG. 3.

S2.3, assembling a middle top plate unit: as shown in fig. 4, the integral assembly of the top plate of the steel box girder is performed in a step sequence from the left center to the right center to the two respective sides from the positioning end; and a central top plate unit is positioned by using a theodolite and taking the marking line of the marking tower as a reference, the central top plate is positioned according to a top plate longitudinal base line, the allowable deviation is 0.5mm, and the central top plate unit is horizontally positioned by using a theodolite and a plumb bob method and taking a top plate transverse base line (a U-shaped rib assembly line) as a reference, wherein the allowable deviation is +/-1 mm.

Positioning the top plate units, wherein the top plate units on two sides of the center line are positioned by taking the center line of the beam section as a reference, drawing a transverse positioning and checking line from the longitudinal base line of the two splicing units on the top plate, which is close to the transverse beam side, to the center side of the beam section, wherein the distance of a return line is 1000mm, and the deviation is 1 mm; longitudinally positioning, namely allowing the deviation to be 2mm by using a method for measuring and checking a plumb bob of a line with a bottom plate; in transverse positioning, a theodolite is used for enabling the theodolite to be aligned with the central line of the upper beam section of the marking tower to adjust the top plate, and the laser point of the theodolite is enabled to be overlapped with the transverse positioning and inspection line of the top plate; and determining the elevation of each measuring point of the top plate by using a level gauge according to the elevation of the measuring point of the top plate after the back viewpoint back calculation, so as to ensure the accuracy of the bridge line shape.

S2.4, primary positioning and assembling of the inner web plate and the anchor web plate unit: as shown in fig. 5, the lower side of the outer anchor web plate is based on an assembly line placed on the inclined bottom plate during transverse positioning, the upper side of the outer anchor web plate is based on a positioning mark line on the marking tower, a transverse base line placed on the central top plate is based on longitudinal positioning, relative dislocation of the upper and lower inner anchor web plates and the outer anchor web plates is corrected by a theodolite, and the movable codes are used for fixing after no error is confirmed, so that spot welding and welding cannot be performed.

S2.5, assembling the rest top plate units: as shown in fig. 6, the roof panels are assembled in order from the middle to both sides, and longitudinal butt welds are applied; when assembling the top plate, attention is paid to: the relative positions of the top plate and the bottom plate are controlled, and the height of the box body is taken into consideration; accurately positioning plate unit pieces of a top plate at the central line of each section of box girder by using a theodolite, wherein the plate unit pieces and the central reference line of the bottom plate are positioned on the same vertical plane; and adjusting the assembly clearance between the plate unit pieces, ensuring that the longitudinal U-shaped ribs of adjacent sections are aligned, and ensuring the relative positions of the top plate joint plate and the diaphragm plate so as to meet the requirement of assembly precision. And welding a corner groove weld at the outer web.

Single sided CO with ceramic liner₂Welding longitudinal butt welding seams among the plate unit pieces; the welding direction is the same as that of the bottom plate, the welding is continuously carried out from one end to the other end, and the welding is carried out according to the sequence of simultaneously and symmetrically welding the central plate unit elements to two sides; after the top plate is assembled, holes are formed according to the included angles of the long axis, the short axis and the bridge center line of the cable hole; and inserting a stay cable guide pipe into the preformed hole of the top plate, assembling the flitch and the guide pipe for stiffening, wherein the stay cable guide pipe can be only spot-welded, and after the stay cable on the bridge is adjusted according to the angle of the guide pipe, the guide pipe and the stay cable are ensured to be concentrically welded.

S2.6, secondary positioning of an anchor web: selecting morning or cloudy day before assembling the side top plate, and when the influence of temperature on the size of the steel plate is small, accurately adjusting the anchor web plate by using the theodolite and the marking line on the marking tower as a reference, and paying attention to the fact that the welding shrinkage is reserved for 3mm during adjustment to ensure the half-width size of the steel box girder after the anchor web plate and the diaphragm plate are welded; the half-width size of the anchor box web is taken as the key control size, one-time positioning is strictly forbidden or positioning is carried out without considering temperature and welding shrinkage, and then welding of the web and the partition plate and welding of the partition plate and the inclined bottom plate are completed.

S2.7, assembling and positioning the middle cross beam: as shown in fig. 7, after the secondary positioning of the anchor web is completed, before the laying of the top plate at the most lateral side is completed, the position line of the partition board is returned to the outer side of the inner web to be used as the positioning reference of the web of the middle cross beam; the middle cross beam is positioned and assembled by a 200-ton crane; after the first section of the steel box girder is installed, a jig frame at the inclined strut position is removed, a bottom plate of the cross beam is hoisted, and after positioning is completed, assembly is carried out according to the sequence of the partition plate, the web plate and the top plate; each crossbeam of each round is carried out after the installation of the segments is completed.

Positioning and assembling the middle cross beam base plate, namely firstly, taking a U-rib assembling datum line on the central base plate as a reference, finding a straight line where a transverse central line of the cross beam base plate is located by using a steel disc ruler, erecting an instrument at the intersection point of a longitudinal base line of the central base plate and the transverse central line of the cross beam base plate, adjusting a line corresponding to a central marking tower to be collinear, rotating by 90 degrees, combining a bridge central line (the central marking tower) to assemble and position the middle cross beam base plate, fixing by using a rigid code after positioning, ensuring that no displacement occurs, and allowing the center to deviate by 0.5; when the side beam bottom plates are assembled, 2-3mm more pushing is required to be performed towards the side of the middle beam to serve as the shrinkage of the welding of the side beam bottom plates and the box beam bottom plates.

Assembling a beam web plate, a partition plate and a top plate, accurately assembling the beam partition plate according to a construction drawing and horizontal and vertical base lines after the elevation of a beam bottom plate is adjusted to be qualified (strictly controlling the elevation deviation of the position of the partition plate to be less than or equal to 2 mm), and ensuring that the verticality deviation of the partition plate is less than or equal to 2 mm; and after welding, assembling a web plate by taking the partition plate as an inner tube, and finally assembling a top plate, wherein the theodolite is used for ensuring that the centers of all cross beams of one turn are collinear, and the allowable deviation is 1 mm.

S2.8, assembling and positioning cantilever arm blocks: as shown in fig. 8, before the outermost top plate unit is assembled, the position line of the partition plate is returned to the outer side of the outer web plate to be used as a reference for accurately positioning the relative position of the cantilever block and the transverse partition plate, and the cantilever is positioned by taking the position line of the partition plate on the outer side of the outer web plate as a reference; the cantilever block body and the web plate are fixed by a movable horse, and a positioning datum line is prepared after positioning is finished, so that the cantilever block body and the web plate are convenient to assemble after sanding and coating; temporary matching pieces are arranged among the cantilever arm blocks, so that the longitudinal matching performance is ensured when the cantilever arm top plate is assembled after coating.

S3, pre-assembling: in order to ensure the smooth erection of the steel box girder, the steel box girder adopts a scheme of completing pre-assembly and welding at one time in an assembly field, and when the dimension of the girder section is found to be wrong or the pre-camber is not consistent, the dimension correction and the dimension adjustment of a matching part can be carried out in the pre-assembly field, so that the adjustment at high altitude is avoided, the high altitude operation difficulty is reduced, the hoisting speed is accelerated, and the erection period is shortened.

Matching and assembling multiple beam sections (at least 5), reserving gaps between the beam sections according to the manufacturing line shape to match the connecting sections of the adjacent beam sections, then welding seams, and cutting the back tower end according to the manufacturing length (reserving welding gaps and welding shrinkage) after welding; the method comprises the steps of accurately adjusting and measuring the line shape, the length, the port size, the straightness and the like, assembling and welding temporary matching parts on a construction site after the line shape, the length, the port size, the straightness and the like are detected to be qualified, conveying out and stacking other beam sections after identification, leaving the last beam section, pre-assembling the beam sections with the subsequent beam sections, wherein the pre-assembling sequence is the same as the beam section hoisting sequence, and the beam section number is not allowed to be changed during hoisting.

The influence of the shrinkage of the welding circular seam and the beam section compression caused by cable force on the length needs to be considered during pre-assembly, and the accumulated total length and error of the previous pre-assembly are suitable for being corrected in the next assembly; and marking the number of the beam section after each wheel of pre-assembly is qualified, leaving the last beam section, participating in the next wheel of pre-assembly, discharging the rest beam sections to enter a coating process, and removing the constraints of the beam sections, such as the stacking plates of the bottom jig frame and the like when the beam sections are pre-assembled with the mother beam, wherein the beam sections are in a free state.

Limited by the width of a coating room, the cantilever arm blocks are accurately assembled and positioned after the box girder segments are coated, and the cantilever arms are weighed and then transported to a girder storage yard to be shipped.

The matters to be noted in the pre-assembly are as follows: the first batch of steel box girders are used as test girder sections, whether the whole manufacturing process is reasonable or not and whether the production measures are proper or not are comprehensively checked, and then the steel box girders are produced in batches after being qualified; the influence of the shrinkage of a welding annular welding seam and the beam section compression caused by cable force on the beam length is considered during pre-assembly, and the length of the beam section pre-assembled at the present time is corrected according to the accumulated total length and errors after the previous pre-assembly, so that the error accumulation is prevented; the size deviation of the ports of the adjacent beam sections is difficult to avoid, and the adjacent ports are matched and trimmed during pre-assembly, so that the adjacent ports are smoothly butted and welded during aerial installation; in order to eliminate the accumulated error of the installation of the steel box girder and ensure the smooth closure of the full bridge, enough trimming allowance is reserved for the closure segment length.

S4, pre-assembly inspection: as shown in fig. 9 and 10, after the whole assembly welding and pre-assembly of each wheel beam section are completed, the pre-assembly inspection is directly performed on the total assembly jig frame, and the key inspection is as follows: the method comprises the steps of bridge longitudinal line shape, beam section longitudinal accumulated length, full-bridge pre-splicing camber, box beam axis central line deviation, transverse slope, distortion and checking the matching condition of the end faces of adjacent sections.

Pre-assembly inspection measurement requirements: for measuring the important dimensions such as elevation, length and the like of each beam section, the influence of sunlight is avoided, and the ambient temperature is recorded; meanwhile, preparation work is required to be done in advance, and the adjusting speed is increased, so that the influence of the settlement of the jack on the elevation of the matched beam section is reduced; before use, the steel strip or standard ruler for measurement should be stored under the same conditions as the workpiece to be detected, so that the temperature of the steel strip or standard ruler is consistent with that of the workpiece to be detected, and the steel strip or standard ruler is periodically sent to a metrological detection department for verification; all measuring tools such as a leveling instrument, a Jingwei instrument, an instrument and the like for measurement need to be calibrated by a two-stage metering mechanism before use and are used as required; the operator is specially trained, takes the certificate on duty and carries out the operation of fixing the person and fixing the instrument; the tension of a tension meter used for measuring the distance of the steel ruler is in accordance with the specification of the steel ruler; during pre-assembly, a measurement control network of a jig frame area is used for field detection, as shown in fig. 11.

Before the two-wheel connecting beam sections are matched, all horse boards connected with the bottom plate and the jig frame are unfastened, and matched and butted in an unconstrained state; because the beam section is divided into a left beam, a right beam and a cross beam, the two box beams and the cross beams are associated when being assembled and positioned, and the assembly and the positioning of a single box beam or a single cross beam are not considered so as to ensure the matching property between the box beams and the cross beams.

After the segment assembly welding repair is finished and the segment is completely assembled and inspected to be qualified, calculating the length of the top plate and the bottom plate according to the manufacturing length of the segment and the pre-camber given by a monitoring unit and considering the assembly clearance of the transverse joint of the construction site, and cutting once by adopting automatic precise flame cutting after scribing to finish the set length and the groove; assembling and welding accessories, temporary cross beams and construction site temporary matching pieces, installing temporary hoisting points, and then integrally discharging the tire; after the tire is removed from the segment, polishing and repairing the overall appearance of the steel box girder, and assembling and welding other accessory components such as a track hanger of the inspection vehicle; and after the appearance is reported and tested, coating the steel box girder and spraying the mark of the girder section.

The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (9)

1. An integral assembling method for an ultra-wide framing steel box girder is characterized by comprising the following steps: the method comprises the following steps of manufacturing plate units, assembling and welding plates, matching and assembling and welding beam sections, pre-assembling and pre-assembling inspection, wherein the pre-assembling and welding are completed at one time, and the method comprises the following specific steps:

s1, manufacturing a plate unit and assembling and welding a plate block:

s1.1, after sampling the steel plate, leveling and preprocessing the steel plate, and then carrying out corresponding processing;

s1.2, plate assembly welding: before the plate units participate in the assembly of the beam sections, the plate units are firstly spliced and welded on a special jig frame to form a hoisting plate block, the center distance of adjacent U-shaped stiffening ribs on two sides of a welding line is controlled by using a sample plate with a reserved welding shrinkage amount during splicing, reverse deformation is preset, and after the two-stage splicing of the plate units is completed, the plate units are turned over by using an integral lifting appliance which is in the form of an integral carrying pole and is provided with 3-5 lifting points;

s2, matching, assembling and welding beam sections: in the manufacturing of the box girder section, assembling and welding section by section in a three-dimensional stepped propelling mode on a total assembly jig frame according to the sequence of a bottom plate, a diaphragm plate, a middle top plate, a primary positioning inner web plate, an anchor web plate, other top plates, a secondary positioning anchor web plate, a middle cross beam and a cantilever arm block body;

s3, pre-assembling: matching and assembling a plurality of beam sections, reserving gaps according to a manufacturing line shape and beam sections to match connecting sections of adjacent beam sections, welding seams, cutting back tower ends according to the manufacturing length after welding, considering the influence of beam section compression caused by welding circular seam shrinkage and cable force on the length during pre-assembling, correcting the accumulated total length and error of the last pre-assembling in the next assembling, accurately adjusting and measuring the line shape, the length, the port size and the straightness, marking the beam section number after each round of pre-assembling is qualified, leaving the last beam section to participate in the next round of pre-assembling, leaving the rest beam sections to enter a coating process, removing the constraint with a bottom tire frame code plate when pre-assembling with a main beam, enabling the beam sections to be in a free state, enabling the pre-assembling sequence to be the same as the beam section hoisting sequence, and not changing the beam section number during hoisting; limited by the width of the coating room, and after the box girder segment is coated, the cantilever block is accurately assembled and positioned;

s4, pre-assembly inspection: and (3) directly performing pre-assembly inspection on the total assembly jig frame after the whole assembly welding and pre-assembly of each wheel beam section are finished, and performing key inspection: the method comprises the steps of bridge longitudinal line shape, beam section longitudinal accumulated length, full-bridge pre-splicing camber, box beam axis central line deviation, transverse slope, distortion and checking the matching condition of the end faces of adjacent sections.

2. The method for integrally assembling the ultra-wide framing steel box girder according to claim 1, wherein: the general assembly jig frame in the step 2 is provided with a longitudinal datum line, a transverse datum line, a datum point and a bridge center line, wherein the longitudinal datum line and the transverse datum line are positioned by a bottom plate unit, a measuring mark tower is arranged at each end of the general assembly jig frame, a datum mark line is arranged on the tower according to process data and is used as an independent measuring net outside the jig frame to detect the jig frame at any time, the general assembly jig frame is provided with tooth plates according to a manufacturing line type, and pre-camber is transversely arranged.

3. The method for integrally assembling the ultra-wide framing steel box girder according to claim 1, wherein: in the step S2, the assembly adopts a normal assembly method, the jig frame is used as an outer tire, the diaphragm plate is used as an inner tire, each plate unit is positioned in position according to the longitudinal and transverse base lines, and a reinforcing facility is used for ensuring the precision and the safety;

bottom plate, cross slab, middle roof, primary location inner web and anchor web, all the other roofs, secondary location anchor web, middle cross beam, the equipment and the welding of the block of the arm of picking are as follows:

s2.1, assembling and welding a bottom plate and a pressure heavy groove of a beam section of a pressure heavy area: firstly, placing a middle bottom plate unit on a total assembly jig frame, positioning by using a theodolite, accurately aligning a transverse base line and a longitudinal base line of the middle bottom plate unit with the base lines on the jig frame under the condition of no sunshine influence, fixing the middle bottom plate unit with the total assembly jig frame, assembling and positioning bottom plates on two sides, then assembling and positioning an inclined bottom plate with the bottom plates according to a web positioning line on the jig frame, welding butt welding seams between a flat bottom plate and the inclined bottom plates, and positioning and assembling a ballast tank after assembling and positioning a beam section flat bottom plate with the ballast tank;

s2.2, assembling and welding diaphragm plate units and reinforcing angular points: using a longitudinal base line on a bottom plate as a reference, positioning the transverse position of a transverse clapboard by using a theodolite, welding a transverse clapboard landing horse plate on the bottom plate, and positioning the transverse base line position of the transverse clapboard by using a leveling instrument so as to determine the height position of the transverse clapboard; all the partition plates are vertically arranged in a bridge state, so that after the arrangement of each partition plate is finished, the angle of the partition plate needs to be adjusted by using a line vertical mode, the slope of the upper edge of the transverse partition plate and the verticality between the transverse partition plate and the bottom plate are well adjusted and controlled, the transverse partition plate is fixed by using a temporary fixing jig, the inner transverse partition plate is assembled firstly during assembly, and then the outer transverse partition plate is assembled, so that the groove mouth of the U rib is ensured not to conflict with the U rib;

s2.3, assembling a middle top plate unit: the integral assembly of the steel box girder top plate is carried out in a step sequence from the left center to the right center to the two sides of the steel box girder top plate respectively from a positioning end, the central top plate unit is positioned, the central top plate is positioned by a theodolite by taking a marking line of a marking tower as a reference according to a longitudinal base line of the top plate, and the transverse direction is positioned by the theodolite and a plumb bob method by taking a transverse base line of the top plate as a reference;

s2.4, primary positioning and assembling of the inner web plate and the anchor web plate unit: the lower edge of the outer anchor web plate is based on an assembly line placed on the inclined bottom plate during transverse positioning, the upper edge of the outer anchor web plate is based on a positioning mark line, a transverse base line placed on the central top plate is based on longitudinal positioning, and meanwhile, theodolites are used for correcting relative dislocation of the upper and lower inner anchor web plates and the outer anchor web plates, and the outer anchor web plates are fixed after no error is confirmed;

s2.5, assembling the rest top plate units: assembling top plate blocks from the middle to two sides, welding longitudinal butt welds, accurately positioning plate unit elements of the top plate at the central line of each section of box girder by using a theodolite, and welding a corner groove weld at an outer web plate, wherein the plate unit elements and the central reference line of the bottom plate are positioned on the same vertical plane;

s2.6, secondary positioning of an anchor web: before assembling the side top plate, when the influence of the temperature on the size of the steel plate is small, the theodolite is reused to accurately adjust the anchor web plate by taking a mark line on the mark tower as a reference, welding shrinkage is reserved during adjustment to ensure the half-width size of the steel box girder after the anchor web plate and the diaphragm plate are welded, and then the welding of the web plate and the diaphragm plate as well as the diaphragm plate and the inclined bottom plate is completed;

s2.7, assembling and positioning the middle cross beam: after secondary positioning of the anchor web is completed, before the top plate at the most lateral side is laid, the position line of the partition plate is returned to the outer side of the inner web to serve as a web plate positioning reference of the middle cross beam, the middle cross beam is positioned and assembled by a crane, after the first section of the steel box beam is installed, a jig at the inclined strut position is removed, the bottom plate of the cross beam is hoisted firstly, after the positioning is completed, the assembly is performed according to the sequence of the partition plate, the web plate and the top plate, and each cross beam of each turn is performed after the section is installed;

s2.8, assembling and positioning cantilever arm blocks: before assembling the outermost top plate unit, the position line of the partition plate is returned to the outer side of the outer web plate to serve as a reference for accurately positioning the relative position of the cantilever block body and the transverse partition plate, the cantilever is positioned by taking the position line of the partition plate on the outer side of the outer web plate as the reference, the cantilever block body and the web plate are fixed, a positioning reference line is made after positioning is completed, and a temporary matching piece is installed between the cantilever block bodies.

4. The method for integrally assembling the ultra-wide framing steel box girder according to claim 1, wherein: in the step S3, the pre-assembly is to use the first batch of steel box girders as test girder segments, comprehensively check whether the whole manufacturing process is reasonable and whether the production measures are proper, and perform batch production after confirmation; according to the accumulated total length and errors after the last pre-assembly, the length of the next pre-assembled beam section is corrected, and the error accumulation is avoided; matching and finishing adjacent ports during pre-assembly; and reserving a trimming allowance for the length of the folded section.

5. The method for integrally assembling the ultra-wide framing steel box girder according to claim 1, wherein: in the step S4, during the pre-assembly inspection and measurement, the elevation and the length of each beam section are measured, so as to avoid the influence of sunlight and record the ambient temperature; preparing before measurement, accelerating the adjustment speed so as to weaken the influence of the jack settlement on the elevation of the matched beam section, storing a steel belt or a standard ruler for measurement under the same condition with a detected workpiece before use, keeping the temperature of the steel belt or the standard ruler consistent with that of the detected workpiece, and periodically detecting the steel belt or the standard ruler;

before the two-wheel connecting beam sections are matched, all horse boards connected with the bottom plate and the jig frame are unfastened, matching and butt joint are carried out in an unconstrained state, and two box beams and two cross beams are associated to be carried out during assembling and positioning so as to ensure the matching property between the box beams and the cross beams.

6. The method for integrally assembling the ultra-wide framing steel box girder according to claim 1, wherein: in the step S1.2, during plate assembly welding, when the plate units are assembled in two, the staggered edge amount of the bevel ends of the two plate units is controlled to be less than or equal to 1mm according to the linear pairing of the longitudinal base lines and the transverse base lines of the plate units, the relative deviation of the connecting plates of the transverse partition plates of the top plate is controlled to be less than or equal to 2mm, the unevenness of four corners is controlled to be less than or equal to 5mm, the diagonal difference is controlled to be less than or equal to 4mm, 30-35mm upward reverse deformation amount is preset at the welding seams when the plate units are assembled in; for transverse positioning, welding shrinkage of 2-3mm is reserved in the width direction of the plate unit.

7. The method for integrally assembling the ultra-wide framing steel box girder according to claim 3, wherein: in the step S2.1, the bottom plate unit is positioned, longitudinal base lines on two sides of a central line of the central bottom plate unit of the beam section are taken as references and used as a positioning and checking line in the direction of the central line of the box girder, the bottom plate at the central line is adjusted, marks at two ends of the bottom plate unit are made to coincide with a straight line where the theodolite is located, the bottom plate is fixed after adjustment, the central bottom plate is ensured not to be displaced, and the positioning of all the bottom plate units on the central line is sequentially completed according to the given;

positioning the bottom plate units on two sides, measuring the distance between longitudinal baselines of two adjacent plates by using a disc ruler, adding 2-3mm welding shrinkage, erecting and adjusting a theodolite at the intersection point of the transverse baselines and the longitudinal baselines on the central bottom plate to enable the theodolite to be collinear with the marker line on the central marker tower, adjusting the plates to enable the end measuring and inspecting line to be superposed with a theodolite control straight line, wherein the misalignment amount of the slope ends of the adjacent plate units is less than or equal to 1mm, and the relative deviation of the cross partition plate connecting plates is less than or equal to 2mm, and sequentially completing the transverse;

assembling and positioning the inner inclined bottom plate and the outer inclined bottom plate, and adjusting the inclined bottom plate to ensure that a longitudinal baseline of the inclined bottom plate is superposed with a control line, wherein the deviation is +2.5 +/-0.5 mm and contains welding shrinkage;

checking a bottom plate stopping point: and after the welding and repairing of the whole round bottom plate and the inclined bottom plate group are finished, carrying out bottom plate elevation inspection, determining that the deviation is qualified if the deviation is not more than +/-2 mm, otherwise, adjusting the bottom plate unit until the elevation is qualified, and taking the inner and outer web positioning mark lines as reference lines after all the welding and repairing of each round beam section are finished as datum lines of assembling and positioning anchor webs to obtain the web positioning net.

8. The method for integrally assembling the ultra-wide framing steel box girder according to claim 3, wherein: in the step S2.3, the middle top plate unit is positioned, the top plate units on two sides of the central line are positioned by taking the central line of the beam section as a reference, a transverse positioning inspection line is drawn from the longitudinal base line of the two splicing units on the top plate close to the beam side to the central side of the beam section, the distance of the return line is 1000mm, and the deviation is 1 mm; and longitudinally positioning, namely adjusting the deviation by 2mm by using a method of measuring and checking a line plumb bob of a line with the bottom plate, transversely positioning, adjusting the top plate by using a theodolite to enable the theodolite to be coincident with the central line of the upper beam section of the marking tower, enabling the laser point of the theodolite to be coincident with the transverse positioning and checking line of the top plate, and determining the elevation of each measuring point of the top plate by using a leveling instrument according to the elevation of the measuring point of the top plate after viewpoint back calculation so as to ensure the.

9. The method for integrally assembling the ultra-wide framing steel box girder according to claim 3, wherein: in the step S2.7, the middle cross beam bottom plate is positioned and assembled, firstly, a straight line where the transverse center line of the cross beam bottom plate is located is found out by using a steel disc ruler by taking a U-rib assembly datum line on a central bottom plate as a reference, an instrument is erected at the intersection point of the longitudinal base line of the central bottom plate and the transverse center line of the cross beam bottom plate, the instrument is adjusted to be collinear with a central marker tower and then rotated by 90 degrees, the central line of a bridge and the central marker tower are combined to assemble and position the middle cross beam bottom plate, the center deviation is 0.5mm, and 2-3mm is pushed to the side of the middle cross beam when the side cross beam bottom plate is assembled to serve as the shrinkage;

assembling the web plate, the partition plate and the top plate of the middle cross beam, adjusting the elevation of a bottom plate of the cross beam, controlling the position elevation deviation of the partition plate to be less than or equal to 2mm, accurately assembling the cross beam partition plate according to the transverse and longitudinal base lines, adjusting the verticality deviation of the partition plate to be less than or equal to 2mm, assembling the web plate by taking the partition plate as an inner tube after welding, finally assembling the top plate, and ensuring that the centers of all cross beams in one turn.

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