CN114892552A - Box girder type bridge reconstruction construction method - Google Patents
Box girder type bridge reconstruction construction method Download PDFInfo
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- CN114892552A CN114892552A CN202210767358.1A CN202210767358A CN114892552A CN 114892552 A CN114892552 A CN 114892552A CN 202210767358 A CN202210767358 A CN 202210767358A CN 114892552 A CN114892552 A CN 114892552A
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Abstract
The invention discloses a box girder type bridge reconstruction construction method which comprises the steps of bridge design, new bridge erection, old bridge reinforcement, bridge deck widening, bridge transverse splicing, double-beam butt joint, bridge deck heightening, old bridge dismantling, bridge deck pavement, post-treatment and the like. The invention realizes a systematic, complete and clear bridge reconstruction method, designs and compares each reconstructed bridge section, and marks a reserved marked bridge section, a bridge section to be dismantled and a corresponding bridge pier in sequence; then according to the design requirement, reinforcing, widening, merging, butting and heightening the bridge sections, and classifying and processing section by section after marking; the invention also provides a novel double-beam butt joint structure and a method, and particularly relates to a T-shaped steel bar binding structure at a joint formed by adopting the hangers to cross and connect steel bars and binding the transverse steel bar rings and the vertical steel bar rings by the steel bars.
Description
Technical Field
The invention relates to the technical field of bridge reconstruction, in particular to a box girder type bridge reconstruction construction method.
Background
With the great increase of the vehicle holding amount in China, a great test is provided for the traffic passing rate of the existing bridge, and meanwhile, the reconstruction of the bridge is more important due to the change of the foundation and the rock layer and the long-term overhaul of the old bridge.
The existing bridge reconstruction usually adopts a mode of butt joint erection of precast beams at two ends, and keeps the original bridge pier unchanged as much as possible so as to save the reconstruction cost, so the size precision requirements on the precast beams, joints and expansion joints are very high, the bridge often has size difference in the actual operation when in butt joint, and the gap between the two butt joint beams cannot be avoided, sometimes, the precast beams are needed to be replaced again due to overlarge gaps, and great influence is brought to the bridge construction progress.
Based on the above, the invention aims to improve the double-beam butt joint process in the existing bridge reconstruction, provide some structural improvements and provide a whole set of bridge reconstruction process.
Disclosure of Invention
The invention aims to solve the defects in the prior art and provides a box girder type bridge reconstruction construction method.
In order to achieve the purpose, the invention adopts the following technical scheme:
a box girder type bridge reconstruction construction method comprises the following steps:
firstly, bridge design:
marking a reserved bridge section, a bridge section to be dismantled and a corresponding bridge pier according to a newly designed bridge route by referring to the mechanical strength of the bridge piers and the main beam; the durability test is carried out on the reserved bridge section, the maximum water cement ratio of the main beam body is required to be 0.55, and the minimum cement consumption is required to be 350kg/m 3 The maximum chloride ion content is 0.06%, and the maximum alkali content is 3.0 kg/m 3 Reinforcing and marking the old bridge which does not reach the standard; carrying out widening marking on the bridge end needing to be transversely widened; carrying out merging marking on bridge sections needing to be transversely merged and spliced; carrying out butt joint marking on bridge sections needing butt joint and assembly; heightening and marking a bridge needing to heighten a bridge deck;
secondly, new bridge erection:
newly-built to increasing the highway section, including pier construction, box roof beam prefabrication, box roof beam hoist and mount and leveling processing, specifically include following process:
1) the girder prefabrication process comprises template manufacturing, pedestal lofting and the like, and the slope arrangement and symmetry of each prefabricated part of the girder caused by longitudinal and transverse slopes of the bridge are required to be noticed, meanwhile, the arrangement sizes and the positions of an expansion joint reserved groove, a negative bending moment beam tensioning groove and a prestressed pipeline are required to be noticed, whether the expansion joint, a guardrail, a water drain pipe, a support, a bridge deck system and other pre-arranged parts of auxiliary facilities are complete or not is strictly checked before the girder concrete is poured, and the girder can be poured without errors;
2) comprehensively considering various factors such as construction procedures, construction period arrangement, environmental influence and the like, ensuring the concrete strength through the experiment, reducing the shrinkage and slow release of the concrete, and ensuring that the sampling and health-preserving conditions of the concrete strength test piece to be filled are matched with the main beam and the beam concrete;
3) when the short T-shaped beam and the T-shaped beam concrete are precast for pouring construction, the beam length and the beam length increment and decrement values are arranged in the uniform section of the midspan section;
4) the abutment back wall is made into an inclined surface according to the longitudinal slope or the anchor sealing end of the upper structure of the abutment end is made into an inclined surface which is vertical to the reference horizontal plane after being in place by considering the influence of the abutment longitudinal slope during prefabrication so as to ensure that the width of the gap between the beam end and the back wall is consistent up and down and ensure that the installation size of the expansion joint and the reserved size of the expansion joint meet the design requirements;
5) for a prestressed structure, prestressed construction should meet technical specifications for highway bridge and culvert construction, a through double-acting jack is adopted for prestressed tension, a jack with a self-anchoring function is adopted for integral tensioning or releasing, channel grouting is carried out after prestressed tendons are tensioned and should be completed within 48h, the end of an anchorage device is timely sealed and protected after grouting is completed, a positive air auxiliary grouting process is adopted for channel grouting, and nondestructive detection or endoscopy is adopted after grouting;
6) suspension casting of box girders:
firstly, the No. 0 segment and the side span cast-in-place segment of the box girder are constructed by adopting a support cast-in-place method, the middle and side span closure segments are constructed by adopting a cast-in-place method on a hanger, the other segments are all cast in a hanging basket suspension manner, a correct casting procedure is required to be established during construction so as to ensure the engineering quality,
secondly, the hanging basket construction process is as follows:
a. before construction, the hanging basket must be assembled and subjected to a weight test to check whether the strength and the rigidity of the hanging basket meet the requirements, and the hanging basket can be formally used after supervision, examination and evaluation;
b. during a hanging basket load test, elastic deformation under corresponding load is measured, so that pre-camber is reasonably set during construction, and the line shape of the box girder is ensured to meet design requirements;
c. after the cradle is in place, the whole equipment, the nodes, the rear anchor system, the front and rear hoisting point systems, the balance system, the brake system, the walking system and the like are comprehensively checked;
d. after the box girder bottom die is installed, measurement is carried out, and whether the central line of the hanging basket is aligned with the central line of the box girder is measured again;
e. the hanging basket is required to observe deformation in time and take effective measures in the pouring process to prevent cracks from being generated among concrete of the box girder sections, and simultaneously, the observation of the concrete near the rear lifting point and the front supporting point is also required to be enhanced;
f. the basket hanging process is unified in command, coordination and coordination, management is strengthened, and safety is guaranteed.
And thirdly, the structure and the stress of the No. 0 block of the variable cross-section box girder are complex, longitudinal, vertical and transverse prestressed pipelines are concentrated, reinforcing steel bars are dense, the volume of concrete is large, necessary measures are needed to control the influence of concrete hydration heat during pouring in order to ensure the structural strength and prevent harmful cracks from occurring, the position of layering is reasonably determined by adopting layered pouring, the age difference of each layer of concrete is as small as possible, and the cracking of the concrete caused by the shrinkage difference of each layer of concrete is avoided. In addition, after the top plate is poured, watering and maintenance inside and outside the No. 0 block piece should be paid attention to practically, ventilation and cooling inside the block piece are enhanced, and the mold is removed in time to avoid cracking of concrete caused by temperature difference between the inside and the outside;
the construction is carried out strictly according to the construction sequence provided by the design, and symmetrical construction is required, wherein the construction comprises that the cantilever casting sections are symmetrical relative to the main pier and the prestressed beams meet the requirement of symmetrical tensioning in the cross section of the box girder as much as possible;
fifthly, the support of the cast-in-place beam section not only needs to meet the strength requirement, but also needs to meet the rigidity requirement, before the concrete box beam is cast formally, a weight test needs to be carried out, the pre-pressing weight is 125% of the weight of the box beam section, so as to ensure safety and eliminate inelastic deformation of the box beam section, and the bottom die elevation and the pre-camber are determined according to the actually measured elastic deformation and the construction control requirement;
when the variable cross-section box girder is constructed, a temporary support system is adopted for the stability and safety of a main pier, the temporary support system consists of a support steel pipe and a prestress system and is a main stressed component in the cantilever construction of the box girder, and when the two cantilevers of the box girder occasionally have asymmetric load action, the temporary support system is an important measure for ensuring the construction safety of the bridge and the stability of the cantilever inclined thin girder; the number, position and number of the steel pipes are determined according to construction safety and construction overturning stability calculation, and participate in structural stress, the size and specification of the supporting steel pipes can be selected by a construction unit, but the strength and rigidity of a supporting system must be ensured;
seventhly, one end of a prestressed steel beam of the temporary support system of the variable-section box beam is embedded in a bearing platform and comprises a pre-embedded P-shaped anchorage device, a corrugated pipe and a spiral rib, the other end of the prestressed steel beam is tensioned and anchored in a box beam bottom plate, and the prestressed steel beam is symmetrically arranged on two sides of the pier and synchronously tensioned; the temporary support is also balanced in balance and does not damage the structure and the appearance, the triangular cushion layer of the temporary support system can ensure that the top surface of the I-beam and the bottom plate of the box beam, the prestressed tendon anchor plate and the bottom plate are closely attached, and the triangular cushion layer is synchronously manufactured during the construction of the bottom plate;
the box girder suspension casting construction process is carried out according to the principle of symmetry, balance and synchronization, the sizes of all parts of the section of the box girder are strictly guaranteed according to construction specifications, the construction is stopped when strong wind occurs in the construction process of a girder section, unbalanced load cannot be obtained at the two cantilever ends as much as possible, only one side is allowed to be overweight by 20 tons under special conditions, and concrete must be poured from the cantilever ends to the direction of a poured block piece when the cantilever block piece is poured, so that vertical cracks at the joint faces of new concrete and old concrete are avoided; the cantilever casting of the beam section is required to be completed by one-time casting, so that the concrete quality of the beam section is ensured;
ninthly, strictly controlling the age difference of adjacent two concrete pouring to be not more than 20 days under any condition, thoroughly removing floating slurry on the joint surface of new and old concrete, chiseling and cleaning, strictly controlling the water cement ratio, reducing the aggregate temperature, reducing the frictional resistance between the template and the concrete, enhancing the maintenance, controlling the formwork removal time, reducing the influence of concrete shrinkage and hydration heat on the structure, and avoiding the generation of shrinkage and hydration heat cracks;
the red part requires that the construction period of each beam section is not less than 10d, and comprises the steps of arranging hanging baskets, erecting formwork binding steel bars, pouring concrete and tensioning longitudinal prestressed bundles, wherein the stress age of the concrete is not less than 10 days;
7) main beam installation:
a. the continuous one-connection construction sequence of the structure is as follows: prefabricating a main beam → erecting a beam, pouring a pier top cast-in-place continuous section and a flange plate, wet joints of a diaphragm plate, tensioning a middle pier top T beam hogging moment steel beam → forming a continuous system → pouring bridge deck pavement concrete → installing guardrails, arranging a bridge deck waterproof withered layer after nine treatments of bridge deck polishing, pouring asphalt concrete pavement, installing accessory facilities → forming a bridge;
b. the precast beam adopts a hoisting method of arranging hoisting holes to penetrate and bundle the beam bottom, the precast beam is careful to keep the transverse stability of the beam body in the processes of transportation, lifting and the like, effective measures are taken to strengthen the transverse temporary support after the precast beam is erected, and cast-in-place continuous section connecting steel bars and only edge plates and diaphragm plate seam steel bars are connected so as to increase the stability and the integrity of the beam body, and the next hole cannot be erected under the condition that the previous hole is not transversely connected;
c. the bridge erection adopts a bridge erecting machine for hoisting, the bridge can be transported on the bridge erecting machine after only the connection of the cross plates between the main girders and the concrete pouring of the wet joints of the grab plates reach 90% of the design grade of the concrete strength and pressure diffusion measures are taken, the bridge erecting machine must be heavy and fall on the beam ribs when the bridge erecting machine runs on the bridge, a construction unit carries out construction load checking calculation on the main girders according to the model of the bridge erecting machine, and the construction can be carried out after the checking calculation is passed;
d. after the cubic strength and elastic modulus of the concrete at the cast-in-place section of the pier top reach 90% of the design grade, tensioning the pier top continuous bundle;
thirdly, reinforcing the old bridge:
prestressing tendons are adopted to apply prestress to the bridge piers, and permanent anchor ears are arranged on the side walls of the bridge piers for bonding and reinforcing; carrying out impact tumor removal, chiseling and disordered steel bar cutting treatment on the damaged bridge deck, and paving steel fiber concrete on the bridge deck to realize bridge deck pavement and reinforcement;
fourthly, widening the bridge deck:
1) the upper structure is as follows: in order to ensure the consistency of the rigidity of the hollow slabs of the new bridge and the old bridge, the load is effectively distributed in the transverse bridge direction, the widened part of the hollow slab is still constructed according to the original design, the original designed hollow slab is checked again, and the bearing capacity of the hollow slab is determined to meet the design load requirement;
2) in order to prevent the bridge deck from cracking, double layers of reinforcing mesh are additionally paved at the joint part of the new bridge and the old bridge so as to ensure the safety of the bridge structure;
3) considering that adverse effects on the stress of the bent cap caused by the inconsistent settlement of the new bridge and the old bridge are possible, when a scheme is formulated, the bent cap of the new bridge and the old bridge is subjected to disconnection treatment;
4) when the old bridge is integrally widened, the arrangement of the bridge and the hollow slab of the widened part meets the following requirements:
the upper structures of the new bridge and the old bridge are matched as much as possible, so that the rigidity of the new widened bridge is basically the same as that of the original bridge, and longitudinal cracks are prevented from being generated due to overlarge deflection difference generated at the joint part of the new bridge and the old bridge because of different rigidity of the new bridge and the old bridge;
secondly, under the condition that the lower part structure of the new bridge meets the stress requirement, a new bridge pile foundation cannot be poured near the original old bridge pile, the pile distance between the new bridge and the old bridge is increased as much as possible, and the influence of the construction process on the foundation structure of the old bridge is prevented;
the elevation of the new bridge is basically consistent with that of the old bridge, and the direct connection of the gradient is noticed, so that the structural stress and the driving on the bridge are facilitated;
fifthly, transversely splicing the bridge:
when the bridge to the case roof beam structure transversely merges, be used for bridge cross section, ramp, pivot frequently, adopt articulated mode to carry out transversely to the case roof beam structure and merge, during specific operation: after the flange concrete at the joint is poured, sawing seams are formed on the top surface of the flange concrete, flexible materials are filled, wood strips or rubber strips are embedded at the bottom of the flange concrete, and the flanges are connected through reinforcing steel bars to form a flexible hinge structure which can not transmit bending moment;
sixthly, double-beam butt joint:
firstly, a new bridge and an old bridge which need to be butted adopt a steel bar pouring connection structure, specifically, rectangular notches are arranged at the opposite positions of the top surfaces of two box girders, a T-shaped cavity structure is formed by a gap between the two box girders and the two rectangular notches, holes are drilled on the side wall and the bottom wall of the rectangular notch, V-shaped suspension loop thin rings are inserted and connected through glue, a plurality of groups of V-shaped suspension loop thin rings are connected with horizontal thin supporting steel bars in a penetrating manner, the thin supporting steel bars are contacted with a plurality of groups of transverse steel bar rings which are arranged in parallel, and a row of straight steel bars I are respectively bound at the inner walls of the top and the bottom of the plurality of groups of transverse steel bar rings;
drilling holes in two side walls of a gap between two box girders, inserting V-shaped lug thick rings through glue, connecting a plurality of groups of V-shaped lug thick rings with horizontal thick support steel bars in a penetrating manner, binding horizontal straight steel bars II between two groups of adjacent thick support steel bars, binding vertical straight steel bars III in the middle of a plurality of straight steel bars II positioned on the same vertical plane, and mutually perpendicular the thick support steel bars, the straight steel bars II and the straight steel bars III;
binding vertical steel bar rings outside the coarse support steel bars, binding and fastening the upper parts of the vertical steel bar rings and part of the straight steel bars I, wherein the part of the straight steel bars I is positioned in the vertical steel bar rings, and the straight steel bars I positioned in the left middle and the right middle are simultaneously bound and fastened with the transverse steel bar rings and the straight steel bars III;
the specific operation is as follows: drilling and fixedly connecting V-shaped suspension loop thin rings and V-shaped suspension loop thick rings, enabling a plurality of groups of V-shaped suspension loop thin rings or V-shaped suspension loop thick rings to form equidistant arrays respectively, penetrating and connecting the thin supporting steel bars in place, and binding the transverse steel bar rings to the thin supporting steel bars; then, suspending the vertical reinforcing steel bar ring in a gap between the two box girders, threading the coarse support reinforcing steel bars in place and binding the coarse support reinforcing steel bars with the vertical reinforcing steel bar ring, binding the straight reinforcing steel bars II to the coarse support reinforcing steel bars, and binding the straight reinforcing steel bars III to the middle parts of the straight reinforcing steel bars II and the transverse reinforcing steel bar ring in sequence; binding all the straight steel bars I into the transverse steel bar rings, binding one part of the straight steel bars I with the vertical steel bar rings, and binding the other part of the straight steel bars I with the straight steel bars III; after the binding is finished, pouring a sealing template, after drying and maintaining, finishing the double-beam butt joint process of the T-shaped cavity structure, and paving a bridge deck pavement layer of steel fiber concrete on the upper surface of the T-shaped cavity structure;
seventhly, heightening the bridge deck:
for some butt-jointed bridges, because the gradient is too high, the heightening treatment is needed for the bridge deck which is too low, the whole heightening project of the bridge usually adopts a broken column jacking scheme, if the whole uplifting height is not high, a method of covering a beam on an original column can be adopted, generally, when the navigation clearance does not meet the requirement, or when the original route is reconstructed and lifted, the old bridge needs to be lifted, and under the condition that the original bridge can meet the current use at all, in order to save the investment and reduce the manufacturing cost, the construction period can be greatly shortened by adopting the scheme;
eighthly, dismantling the old bridge:
the old bridge dismantling comprises dismantling of the whole upper structure and the lower structure, the bridge dismantling safety is very important, and a detailed construction scheme and construction organization are required to be made before construction, so that the bridge dismantling safety is ensured;
the old bridge removal should follow the principle: firstly, building and then dismantling, and then building and dismantling; according to the principle of symmetry and uniformity, for a rigid frame arch bridge with high thrust, uniform unloading is required to be realized in order to prevent overlarge displacement deformation in the bridge dismantling process, wherein a midspan is firstly carried out, then a side span is carried out, a solid abdomen section is firstly carried out, and then an arch leg section is symmetrically dismantled from top to bottom layer by layer; when the cast-in-place pile is involved, chiseling the pile to be 2 meters below the river elevation;
ninth, bridge deck pavement and post-treatment:
after the main beam structures of all the bridges are finished, the guardrails, the electric power facility pipelines and the drainage structures are laid, and then continuous paving is adopted to perform paving, vibrating, joint cutting and maintaining, so that the bridge reconstruction process is finished.
Preferably, in the step six, the die sealing plate in the double-beam butt joint is poured by punching holes at two ends of the thick supporting steel bar and extending out of the die block, the two extending ends of the thick supporting steel bar after pouring forming are additionally provided with anchoring plates, and a stay cable is installed through an anchorage device and a clamping piece to serve as a prestressed support, so that the function of cable-stayed support is realized.
Preferably, the inner walls of the T-shaped cavity structures in the step six and the double-beam butt joint are all subjected to roughening treatment in advance, so that concrete pouring and bonding are facilitated.
Preferably, certain gaps are reserved between the two sides of the outer ring of the vertical reinforcing ring in the step six and the side walls of the two box girders respectively, so that concrete can be poured into the gaps conveniently, and the problem that the bonding effect is poor due to the fact that the vertical reinforcing ring is directly contacted with the box girders is avoided.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention realizes a systematic, complete and clear bridge reconstruction method, designs and compares each reconstructed bridge section, and marks a reserved marked bridge section, a bridge section to be dismantled and a corresponding bridge pier in sequence; then according to the design requirement, reinforcing, widening, combining, butting and heightening marks are carried out on each bridge section, so as to obtain a bridge reconstruction process of bridge design, new bridge erection, old bridge reinforcement, bridge deck widening, bridge transverse splicing, double-beam butting, bridge deck heightening, old bridge dismantling, bridge deck pavement and post-treatment;
2. the invention further provides a novel double-beam butt joint structure and a novel double-beam butt joint method, particularly aiming at the problems that the strength is poor when the existing bridge is in butt joint, and a butt joint part cannot be provided with a pier in some cases.
Drawings
FIG. 1 is a schematic view of a steel bar pouring structure in a double-beam butting step in the invention;
in the figure: the bridge deck comprises rectangular notches 1, V-shaped suspension loop thin rings 2, thin supporting steel bars 3, transverse steel bar rings 4, straight steel bars I5, V-shaped suspension loop thick rings 6, thick supporting steel bars 7, straight steel bars II8, straight steel bars III9, vertical steel bar rings 10 and a bridge deck pavement layer 11.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Engineering for modifying Nanhong bridge of X3I3 Luoyou line
A bridge structure:
the main bridge of the Nanhong bridge adopts a variable cross-section prestressed concrete continuous box girder, and the approach bridge adopts a simply supported and then continuously short T girder and a simply supported and then continuously T girder; the superstructure of the small harbor bridge adopts 10m prestressed concrete simply supported short T-shaped beams. The bridge pier of the lower structure adopts rectangular piers and column piers, the bridge abutment adopts a column abutment, and the abutment foundation adopts a pile foundation.
(II) main material
1. Concrete and its production method
1) The upper structure is as follows:
60+100+60m variable cross-section continuous beam: c55 concrete;
prestressed concrete T-beam and short T-beam: c50 concrete:
and (3) paving the concrete upper bridge deck: c50 concrete:
secondary shrinkage seam: c50 basalt fiber concrete:
the anti-shield fence: c30 concrete.
2) The lower structure is as follows:
ground tie beam, cushion cap, pile foundation: C3O concrete;
column: c30 concrete.
Main pier body of continuous beam: C4O concrete;
reinforced concrete bent cap, dog and fender apron: C3O concrete:
bridge abutment ear-back picking and corbel: c30 concrete;
the bridge protection slope is protected by planting grass in a prefabricated concrete hollow hexagonal block.
2. Steel material
l) ordinary steel bars: except for special description, the diameter of the steel bar is less than 12mm, HPB300 plain round steel bar is adopted, the diameter of the steel bar is more than 12mm HRB40O ribbed steel bar, and the technical performance of the ribbed steel bar respectively accords with the 1 st part of steel for reinforced concrete: hot-rolled plain steel bar (GB 1499.1-2008) and its modification, reinforced concrete, steel for several purposes, part 2: hot rolled ribbed bars (GB 1499.2-2007).
2) The bridge deck pavement steel bars adopt D10 cold-rolled ribbed steel bars and are connected with a steel bar net in a light-transmitting manner, and the main technical indexes of the steel bar net meet the requirements of the cold-rolled ribbed steel bar standard (GB 13788-2008). The meshes are overlapped by adopting an overlapping method, the overlapping length is 25cm, the adjacent meshes are overlapped by staggering 50cm, and the specific requirements are detailed in the technical specification of the reinforced welded mesh concrete structure (JGJ 114-.
3) Pre-stressing a steel strand: adopting a high-strength low-relaxation stranded steel wire of the Standard of prestressed concrete Steel Strand (GB/T5224-2014), the diameter is phi 15.2mm, and the area is A =140mm 2 The standard value f of tensile strength pk =186OMPa, stress relaxation rate after 1000h is not more than 2.5%, and elastic modulus E of steel strand p ＝l.95*10 5 MPa。
4) The prestressed anchorage device: finished anchorage devices and supporting equipment thereof are required to be adopted, and the requirements of anchorage devices, clamps and connectors for prestressed tendons (GB/T14370-. All anchor device codes appearing in the design file are only used as a structure display disc and not used as specified requirements, and anchor devices with reliable quality and performance indexes meeting the requirements can be selected during construction.
5) A prestress system: the requirements of the international prestressed concrete institute (FIP) acceptance suggestion of the post-tensioned prestressed system are met. The pore-forming of the prestressed pipeline adopts a Qingqing corrugated pipe which meets the requirements of plastic corrugated pipes for top stress concrete bridges (JT/T529-. The longitudinal and vertical prestressed pipelines of the main bridge of the Nanhong bridge adopt high-density polyethylene plastic corrugated pipes, and the transverse prestressed pipelines adopt flat plastic corrugated pipes. The parameters adopted for the calculation of the plastic corrugated pipe pipeline are as follows: coefficient of friction μ =0.17, coefficient of variation κ = 0.0015. Before the prestressed steel beam is tensioned, a pipeline friction resistance test is carried out.
6) Other steels: except special regulations, the other parts all adopt Q235 steel, and the technical performance of the steel must meet the regulations of the national standard 'carbon structural steel' (GB/T700-.
3. Bridge support:
the technical performance of the low T beam meets the regulations of road bridge plate type rubber support (JT/T4-2004) and road bridge plate type rubber support specification series (JT/T663-2006). The support must be a professional manufacturer product passing provincial level certification.
2) The continuous beam and the T beam adopt basin-type rubber supports, and the technical performance of the continuous beam and the T beam accords with the regulation of highway bridge basin-type supports (JT/T39-2009). The support must be a professional manufacturer product passing provincial level certification.
4. Secondary shrinkage seam: the specific form of the expansion joint can be adjusted after being determined by an owner. The temporary design principle of the construction drawing is as follows: type 80 and type 80 below use a different criminal steel contraction device, the rubber category of which is butadiene rubber: more than 80 moulds adopt a modulus type telescopic device. The technical performance of the telescopic device meets the regulations of the general technical conditions for the telescopic device of the highway bridge (JT/327) 2016) of the traffic industry standard of the people's republic of China. The telescopic device must be a professional manufacturer product passing provincial level identification.
5. Mechanical joint: the requirement of I-grade joint in the technical specification of mechanical connection of steel bars (JGJ 107-2016) is met. The mechanical connection is adopted for the extension of the stressed main steel bar with the diameter of the steel bar being more than or equal to 22mm, and a tender and thick straight thread steel bar joint or a sleeve extrusion steel bar joint is suggested.
6. Bridge floor waterproof layer: the method is characterized in that firstly, shot blasting and sanding treatment is carried out on a bridge deck, and the well treats bridge deck surface diseases such as surface cracks, rib leakage, pits and the like, so that the bridge deck is guaranteed to be dry, flat and clean.
The waterproof bonding layer of the bridge deck adopts premixed asphalt macadam, the asphalt adopts hot modified asphalt, and the spreading is controlled to be 1.1-1.2kg/m 3 The spraying temperature of the hot asphalt is preferably 135-165 ℃, the particle size of the crushed stone is 4.75-9.5mm, the content of the asphalt and the river content of the premixed crushed stone is 0.4-0.6%, the temperature of the premixed crushed stone and the mountain material is not lower than 150 ℃, and the dosage of the mineral material is preferably 9-10kkg/m 3 。
The technical requirements of the bridge deck waterproof bonding layer are as follows:
TABLE 1 technical requirements for bridge deck waterproofing bonding layer
7. The material and the engineering quality should meet the requirements of the road engineering quality inspection and assessment standards (JTGF 80/1-2017) and the road and bridge construction technical specifications (JTG/TF 50-2011).
(III) bridge design
l, nan hong bridge
The span of the old bridge of the Nanhong bridge is 6.5+5+72+5+6.5, the upper part of the main bridge is a rigid frame arch bridge, the lower part of the main bridge is an open caisson foundation, the upper part of the approach bridge is a concrete beam bridge, and the lower part of the approach bridge is a pile-connected capping beam. 30m retaining walls are respectively arranged at two sides of the bridgehead. The clear width of the bridge deck is 7.4m, and the clear width of the road surface of the retaining wall is 9.2 m. The bridge deck pavement is concrete pavement, and the pavement is asphalt concrete pavement.
Newly-built bridge center stake number K22+579, the bridge is joined in marriage and is striden: 3 × l6+8 × 30+60+100+60+8 × 30m, bridge length 755.12m, bridge width 32.5 m. The upper part of the main bridge adopts a 60+100+60m variable cross-section prestressed concrete continuous box girder structure, the approach bridge adopts a prestressed concrete short T beam and a prestressed concrete T beam, the main pier of the lower structure adopts rectangular solid piers and a bearing platform is connected with grouped piles, the lower parts of the transition pier and the approach bridge adopt column piers and platforms, a bored pile is adopted to serve as a foundation, and the pier-platform pile foundation is designed according to friction piles. The main cross-first sight Jiansu line channel (planning level III channel) of the wood bridge has the navigation clearance of 60 x 7m, the highest navigation water level of 1.96m, and the right deflection angle between the main bridge and the channel central line is 92 degrees.
2. Small harbor bridge
1-14m rigid frame arch bridge of the old bridge of the small port bridge. The two sides of the bridgehead are provided with 4m retaining walls respectively. The net width of the bridge deck is 7m, the bridge deck pavement is concrete pavement, and the bridge head pavement is asphalt concrete pavement. The south side of the bridge is provided with a water pipe.
Newly-built bridge center stake number K23+189, the bridge is joined in marriage and is strideed: 3 x 10m, the right deflection angle of the bridge is 100 degrees, the bridge length is 34.8m, and the bridge width is 20 m. The upper structure of the bridge adopts a simply supported prestressed broken short T-shaped beam, the lower structure adopts a pile-column type pier and a bored cast-in-place pile foundation, and the pier pile foundation is designed according to a friction pile.
(IV) attachment structure
1) This project bridge pile foundation all sets up the sounding pipe. According to the regulation of 3.1.3 of the technical code for dynamic measurement of foundation piles in highway engineering, an acoustic pipe is buried in a pile foundation, and the pile foundation is detected by an ultrasonic method.
3) The construction process of the expansion joint comprises the following steps: the telescopic part is filled with low-grade mortar, the asphalt pavement is integrally paved, and the telescopic device is constructed by cutting the groove.
4) Centralized drainage: centralized drainage is adopted for the main bridge crossing the channel. The maximum continuous length of the centralized drainage pipeline is about 60m, and then the centralized drainage pipeline is drained to the ground along the bridge pier. The pipeline is laid according to the bridge floor longitudinal slope, and is fixed through the jib, and the jib mounting hole site need be paid attention to when the box girder is cast-in-place.
5) Others
The water drain pipe is provided with: the single-span single side of the short T beam with the length of 10m is provided with 2 drainage pipes with the spacing of about snl, the distance between the drainage pipes at the expansion joint (low side) and the beam end is 1.5m, the rest is 3.sm away from the beam end, the single-span single side of the short T beam with the length of 16m is provided with 3 drainage pipes with the spacing of about 5m, the distance between the drainage pipes at the contraction joint (low side) and the beam end is l,5m, the rest is 2.5m, the distance between the drainage pipes at the single-span single side of the beam end is 30mT, the spacing is about 5m, the distance between the drainage pipes at the expansion joint (low side) and the beam end is l.7m, and the rest is 2.5m away from the beam end.
According to the above data and referring to fig. 1, the invention provides a box girder type bridge reconstruction construction method, which comprises the following steps:
firstly, bridge design:
marking a reserved bridge section, a bridge section to be dismantled and a corresponding bridge pier according to a newly designed bridge route by referring to the mechanical strength of the bridge piers and the main beam; to reserved bridgeThe durability test of the beam section requires that the maximum water-cement ratio of the main beam body is 0.55 and the minimum cement consumption is 350kg/m 3 The maximum chloride ion content is 0.06%, and the maximum alkali content is 3.0 kg/m 3 Reinforcing and marking the old bridge which does not reach the standard; carrying out widening marking on the bridge end needing to be transversely widened; carrying out merging marking on bridge sections needing to be transversely merged and spliced; carrying out butt joint marking on bridge sections needing butt joint and assembly; heightening and marking a bridge needing to heighten a bridge deck;
secondly, new bridge erection:
newly-built to increasing the highway section, including pier construction, box roof beam prefabrication, box roof beam hoist and mount and leveling processing, specifically include following process:
1) the process of prefabricating the main beam comprises the steps of manufacturing a template, lofting a pedestal and the like, wherein the gradient arrangement and symmetry of each prefabricated part of the main beam caused by longitudinal and transverse slopes of a bridge are required to be paid attention to, meanwhile, the arrangement sizes and the positions of an expansion joint reserved groove, a negative bending moment bundle tensioning groove and a prestressed pipeline (beam end negative bending moment bundle flat pipe is required to be extended outwards for butt joint) are required to be paid attention to, whether the expansion joint, a guardrail, a drain pipe, a support, a bridge deck system and other pre-arranged parts of auxiliary facilities are complete or not is strictly required to be checked before concrete of the main beam is poured, and the pouring can be carried out after no fault is determined;
2) comprehensively considering various factors such as construction procedures, construction period arrangement, environmental influence and the like, ensuring the concrete strength through the experiment, reducing the shrinkage and slow release of the concrete, and ensuring that the sampling and health-preserving conditions of the concrete strength test piece to be filled are matched with the main beam and the beam concrete;
3) when the short T-shaped beam and the T-shaped beam concrete are precast for pouring construction, the beam length and the beam length increment and decrement values are arranged in the uniform section of the midspan section;
4) the abutment back wall is made into an inclined surface according to the longitudinal slope or the anchor sealing end of the upper structure of the abutment end is made into an inclined surface which is vertical to the reference horizontal plane after being in place by considering the influence of the abutment longitudinal slope during prefabrication so as to ensure that the width of the gap between the beam end and the back wall is consistent up and down and ensure that the installation size of the expansion joint and the reserved size of the expansion joint meet the design requirements;
5) for a prestressed structure, prestressed construction should meet technical specifications for highway bridge and culvert construction, a through double-acting jack is adopted for prestressed tension, a jack with a self-anchoring function is adopted for integral tensioning or releasing, channel grouting is carried out after prestressed tendons are tensioned and should be completed within 48h, the end of an anchorage device is timely sealed and protected after grouting is completed, a positive air auxiliary grouting process is adopted for channel grouting, and nondestructive detection or endoscopy is adopted after grouting;
6) suspension casting of box girders:
firstly, the No. 0 segment and the side span cast-in-place segment of the box girder are constructed by adopting a support cast-in-place method, the middle and side span closure segments are constructed by adopting a cast-in-place method on a hanger, the other segments are all cast in a hanging basket suspension manner, a correct casting procedure is required to be established during construction so as to ensure the engineering quality,
secondly, the hanging basket construction process is as follows:
a. before construction, the hanging basket must be assembled and subjected to a weight test to check whether the strength and the rigidity of the hanging basket meet the requirements, and the hanging basket can be formally used after supervision, examination and evaluation;
b. during a hanging basket load test, elastic deformation under corresponding load is measured, so that pre-camber is reasonably set during construction, and the line shape of the box girder is ensured to meet design requirements;
c. after the cradle is in place, the whole equipment, the nodes, the rear anchor system, the front and rear hoisting point systems, the balance system, the brake system, the walking system and the like are comprehensively checked;
d. after the box girder bottom die is installed, measurement is carried out, and whether the central line of the hanging basket is aligned with the central line of the box girder is measured again;
e. the hanging basket is required to observe deformation in time in the pouring process and take effective measures (such as methods of deformation adjustment, pre-deformation and the like) to prevent cracks from being generated among concrete of the box girder sections, and simultaneously, the observation of concrete near a rear lifting point and a front supporting point is also required to be enhanced;
f. the basket hanging process is unified in command, coordination and coordination, management is strengthened, and safety is guaranteed.
And thirdly, the structure and the stress of the No. 0 block of the variable cross-section box girder are complex, longitudinal, vertical and transverse prestressed pipelines are concentrated, reinforcing steel bars are dense, the volume of concrete is large, necessary measures are needed to control the influence of concrete hydration heat during pouring in order to ensure the structural strength and prevent harmful cracks from occurring, the position of layering is reasonably determined by adopting layered pouring, the age difference of each layer of concrete is as small as possible, and the cracking of the concrete caused by the shrinkage difference of each layer of concrete is avoided. In addition, after the top plate is poured, watering and maintenance inside and outside the No. 0 block piece should be paid attention to practically, ventilation and cooling inside the block piece are enhanced, and the mold is removed in time to avoid cracking of concrete caused by temperature difference between the inside and the outside;
the construction is carried out strictly according to the construction sequence provided by the design, and symmetrical construction is required, wherein the construction comprises that the cantilever casting sections are symmetrical relative to the main pier and the prestressed beams meet the requirement of symmetrical tensioning in the cross section of the box girder as much as possible;
fifthly, the support of the cast-in-place beam section not only needs to meet the strength requirement, but also needs to meet the rigidity requirement, before the concrete box beam is cast formally, a weight test needs to be carried out, the pre-pressing weight is 125% of the weight of the box beam section, so as to ensure safety and eliminate inelastic deformation of the box beam section, and the bottom die elevation and the pre-camber are determined according to the actually measured elastic deformation and the construction control requirement;
when the variable cross-section box girder is constructed, a temporary support system is adopted for the stability and safety of a main pier, the temporary support system consists of a support steel pipe and a prestress system and is a main stressed component in the cantilever construction of the box girder, and when the two cantilevers of the box girder occasionally have asymmetric load action, the temporary support system is an important measure for ensuring the construction safety of the bridge and the stability of the cantilever inclined thin girder; the number, position and number of the steel pipes are determined according to construction safety and construction overturning stability calculation, and participate in structural stress, the size and specification of the supporting steel pipes can be selected by a construction unit, but the strength and rigidity of a supporting system must be ensured;
seventhly, one end of a prestressed steel beam of the temporary support system of the variable-section box beam is embedded in a bearing platform and comprises a pre-embedded P-shaped anchorage device, a corrugated pipe and a spiral rib, the other end of the prestressed steel beam is tensioned and anchored in a box beam bottom plate, and the prestressed steel beam is symmetrically arranged on two sides of the pier and synchronously tensioned; the temporary support is also balanced in balance and does not damage the structure and the appearance, the triangular cushion layer of the temporary support system can ensure that the top surface of the I-beam and the bottom plate of the box beam, the prestressed tendon anchor plate and the bottom plate are closely attached, and the triangular cushion layer is synchronously manufactured during the construction of the bottom plate;
during the suspension casting construction of the box girder, construction is carried out according to the principle of symmetry, balance and synchronization, the sizes of all parts of the section of the box girder are strictly guaranteed according to construction specifications, the construction is stopped when strong wind forecast occurs in the construction process of the girder section, unbalanced load is not obtained at two cantilever ends as much as possible, only one side is allowed to be overweight by 20 tons under special conditions, concrete must be cast from the cantilever ends to the direction of a cast block piece when the cast block piece is cast, and vertical cracks are prevented from occurring at the joint surface of new and old concrete; the cantilever casting of the beam section is required to be completed by one-time casting, so that the concrete quality of the beam section is ensured;
ninthly, strictly controlling the age difference of adjacent two concrete pouring to be not more than 20 days under any condition, thoroughly removing floating slurry on the joint surface of new and old concrete, chiseling and cleaning, strictly controlling the water cement ratio, reducing the aggregate temperature, reducing the frictional resistance between the template and the concrete, enhancing the maintenance, controlling the formwork removal time, reducing the influence of concrete shrinkage and hydration heat on the structure, and avoiding the generation of shrinkage and hydration heat cracks;
the red part requires that the construction period of each beam section is not less than 10d, and comprises the steps of arranging hanging baskets, erecting formwork binding steel bars, pouring concrete and tensioning longitudinal prestressed bundles, wherein the stress age of the concrete is not less than 10 days;
7) mounting a main beam:
a. the continuous one-connection construction sequence of the structure is as follows: prefabricating a main beam → erecting a beam, pouring a pier top cast-in-place continuous section and a flange plate, wet joints of a diaphragm plate, tensioning a middle pier top T beam hogging moment steel beam → forming a continuous system → pouring bridge deck pavement concrete → installing guardrails, arranging a bridge deck waterproof withered layer after nine treatments of bridge deck polishing, pouring asphalt concrete pavement, installing accessory facilities → forming a bridge;
b. the precast beam adopts a hoisting method of arranging hoisting holes to penetrate and bundle the beam bottom, the precast beam is careful to keep the transverse stability of the beam body in the processes of transportation, lifting and the like, effective measures are taken to strengthen the transverse temporary support after the precast beam is erected, and cast-in-place continuous section connecting steel bars and only edge plates and diaphragm plate seam steel bars are connected so as to increase the stability and the integrity of the beam body, and the next hole cannot be erected under the condition that the previous hole is not transversely connected;
c. the bridge erection adopts a bridge erecting machine for hoisting, the bridge can be transported on the bridge erecting machine after only the connection of the cross plates between the main girders and the concrete pouring of the wet joints of the grab plates reach 90% of the design grade of the concrete strength and pressure diffusion measures are taken, the bridge erecting machine must be heavy and fall on the beam ribs when the bridge erecting machine runs on the bridge, a construction unit carries out construction load checking calculation on the main girders according to the model of the bridge erecting machine, and the construction can be carried out after the checking calculation is passed;
d. after the cubic strength and elastic modulus of the concrete at the cast-in-place section of the pier top reach 90% of the design grade, tensioning the pier top continuous bundle;
thirdly, reinforcing the old bridge:
prestressing tendons are adopted to apply prestress to the bridge piers, and permanent anchor ears are arranged on the side walls of the bridge piers for bonding and reinforcing; carrying out impact tumor removal, chiseling and disordered steel bar cutting treatment on the damaged bridge deck, and paving steel fiber concrete on the bridge deck to realize bridge deck pavement and reinforcement;
fourthly, widening the bridge deck:
1) the upper structure is as follows: in order to ensure the consistency of the rigidity of the hollow slabs of the new bridge and the old bridge, the load is effectively distributed in the transverse bridge direction, the widened part of the hollow slab is still constructed according to the original design, the original designed hollow slab is checked again, and the bearing capacity of the hollow slab is determined to meet the design load requirement;
2) in order to prevent the bridge deck from cracking, double layers of reinforcing mesh are additionally paved at the joint part of the new bridge and the old bridge so as to ensure the safety of the bridge structure;
3) considering that adverse effects on the stress of the bent cap caused by the inconsistent settlement of the new bridge and the old bridge are possible, when a scheme is formulated, the bent cap of the new bridge and the old bridge is subjected to disconnection treatment;
4) when the old bridge is integrally widened, the arrangement of the bridge and the hollow slab of the widened part meets the following requirements:
the upper structures of the new bridge and the old bridge are matched as much as possible, so that the rigidity of the new widened bridge is basically the same as that of the original bridge, and longitudinal cracks are prevented from being generated due to overlarge deflection difference generated at the joint part of the new bridge and the old bridge because of different rigidity of the new bridge and the old bridge;
secondly, under the condition that the lower part structure of the new bridge meets the stress requirement, a new bridge pile foundation cannot be poured near the original old bridge pile, the pile distance between the new bridge and the old bridge is increased as much as possible, and the influence of the construction process on the foundation structure of the old bridge is prevented;
the elevation of the new bridge is basically consistent with that of the old bridge, and the direct connection of the gradient is noticed, so that the structural stress and the driving on the bridge are facilitated;
fifthly, transversely splicing the bridge:
when the bridge to the case roof beam structure transversely merges, be used for bridge cross section, ramp, pivot frequently, adopt articulated mode to carry out transversely to the case roof beam structure and merge, during specific operation: after the flange concrete at the joint is poured, sawing seams are formed on the top surface of the flange concrete, flexible materials are filled, wood strips or rubber strips are embedded at the bottom of the flange concrete, and the flanges are connected through reinforcing steel bars to form a flexible hinge structure which can not transmit bending moment;
sixthly, double-beam butt joint:
firstly, a new bridge and an old bridge which need to be butted adopt a steel bar pouring connection structure, specifically, rectangular notches 1 are arranged at the opposite positions of the top surfaces of two box girders, a gap between the two box girders and the two rectangular notches 1 form a T-shaped cavity structure, holes are drilled on the side wall and the bottom wall of the rectangular notch 1, V-shaped suspension loop thin rings 2 are inserted and connected through glue, a plurality of groups of V-shaped suspension loop thin rings 2 are penetrated and connected with horizontal thin supporting steel bars 3, the thin supporting steel bars 3 are contacted with a plurality of groups of transverse steel bar rings 4 which are arranged in parallel, and a row of straight steel bars I5 are respectively bound at the inner walls of the top and the bottom of the plurality of groups of transverse steel bar rings 4;
drilling holes in two side walls of a gap between two box girders, inserting V-shaped lug coarse rings 6 through glue, connecting a plurality of groups of V-shaped lug coarse rings 6 with horizontal coarse support steel bars 7 in a penetrating manner, binding horizontal straight steel bars II8 between two groups of adjacent coarse support steel bars 7, binding vertical straight steel bars III9 in the middle of a plurality of straight steel bars II8 positioned on the same vertical plane, and mutually perpendicular the coarse support steel bars 7, the straight steel bars II8 and the straight steel bars III9 in pairs;
thirdly, vertical reinforcing steel bars 10 are bound on the outer sides of the coarse supporting reinforcing steel bars 7, the upper portions of the vertical reinforcing steel bars 10 are bound and fastened with partial straight reinforcing steel bars I5, the partial straight reinforcing steel bars I5 are located on the vertical reinforcing steel bars 10, and the straight reinforcing steel bars I5 located in the left middle and the right middle are bound and fastened with the transverse reinforcing steel bars 4 and the straight reinforcing steel bars III9 at the same time;
the specific operation is as follows: drilling and fixedly connecting V-shaped suspension loop thin rings 2 and V-shaped suspension loop thick rings 6, enabling a plurality of groups of V-shaped suspension loop thin rings 2 or V-shaped suspension loop thick rings 6 to form an equidistant array respectively, penetrating and connecting the thin supporting steel bars 3 in place, and binding the transverse steel bar rings 4 to the thin supporting steel bars 3; then the vertical reinforcing steel bar rings 10 are suspended in the gaps between the two box girders, the coarse supporting reinforcing steel bars 7 are penetrated in place and bound with the vertical reinforcing steel bar rings 10, the straight reinforcing steel bars II8 are bound to the coarse supporting reinforcing steel bars 7, and the straight reinforcing steel bars III9 are bound to the middle parts of the straight reinforcing steel bars II8 and the transverse reinforcing steel bar rings 4 in sequence; binding all the straight steel bars I5 into the transverse steel coils 4, binding one part of the straight steel bars I5 with the vertical steel coils 10, and binding the other part of the straight steel bars I5 with the straight steel bars III 9; after the binding is finished, pouring a sealing template, after drying and maintaining, finishing the double-beam butt joint process of the T-shaped cavity structure, and paving a bridge deck pavement layer 11 of steel fiber concrete on the upper surface of the T-shaped cavity structure;
seventhly, heightening the bridge deck:
for some butt-jointed bridges, because the gradient is too high, the heightening treatment is needed for the bridge deck which is too low, the whole heightening project of the bridge usually adopts a broken column jacking scheme, if the whole uplifting height is not high, a method of covering a beam on an original column can be adopted, generally, when the navigation clearance does not meet the requirement, or when the original route is reconstructed and lifted, the old bridge needs to be lifted, and under the condition that the original bridge can meet the current use at all, in order to save the investment and reduce the manufacturing cost, the construction period can be greatly shortened by adopting the scheme;
eighthly, dismantling the old bridge:
the old bridge dismantling comprises dismantling of the whole upper structure and the lower structure, the bridge dismantling safety is very important, and a detailed construction scheme and construction organization are required to be made before construction, so that the bridge dismantling safety is ensured;
the old bridge removal should follow the principle: firstly, building and then dismantling, and then building and dismantling; according to the principle of symmetry and uniformity, for a rigid frame arch bridge with high thrust, uniform unloading is required to be realized in order to prevent overlarge displacement deformation in the bridge dismantling process, wherein a midspan is firstly carried out, then a side span is carried out, a solid abdomen section is firstly carried out, and then an arch leg section is symmetrically dismantled from top to bottom layer by layer; when the cast-in-place pile is involved, chiseling the pile to be 2 meters below the river elevation;
ninth, bridge deck pavement and post-treatment:
after the main beam structures of all the bridges are finished, the guardrails, the electric power facility pipelines and the drainage structures are laid, and then continuous paving is adopted to perform paving, vibrating, joint cutting and maintaining, so that the bridge reconstruction process is finished.
Referring to fig. 1, in the step six, the two ends of the thick supporting steel bar 7 are perforated and extend out of the module in the pouring of the die sealing plate in the double-beam butt joint, the extending two ends of the thick supporting steel bar 7 after pouring forming are additionally provided with anchor plates, and stay cables are installed through anchors and clamping pieces to serve as prestressed supports, so that the stay cable supporting effect is realized.
Referring to fig. 1, in the sixth step, the inner walls of the T-shaped cavity structures in the double-beam butt joint are all subjected to roughening treatment in advance, so that concrete is conveniently poured and bonded.
Referring to fig. 1, in the sixth step, certain gaps are reserved between the two sides of the outer ring of the vertical steel bar ring 10 in the double-beam butt joint and the side walls of the two box beams, so that concrete can be poured into the gaps conveniently, and the problem that the vertical steel bar ring 10 is in direct contact with the box beams to cause poor bonding effect is avoided.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (4)
1. A box girder type bridge reconstruction construction method is characterized by comprising the following steps:
firstly, bridge design:
marking a reserved bridge section, a bridge section to be dismantled and a corresponding bridge pier according to a newly designed bridge route by referring to the mechanical strength of the bridge piers and the main beam; the durability test is carried out on the reserved bridge section, the maximum water cement ratio of the main beam body is required to be 0.55, and the minimum cement consumption is required to be 350kg/m 3 The maximum chloride ion content is 0.06%, and the maximum alkali content is 3.0 kg/m 3 Reinforcing and marking the old bridge which does not reach the standard; carrying out widening marking on the bridge end needing to be transversely widened; carrying out merging marking on bridge sections needing to be transversely merged and spliced; carrying out butt joint marking on bridge sections needing butt joint and assembly; heightening and marking a bridge needing to heighten a bridge deck;
secondly, new bridge erection:
newly-built to increasing the highway section, including pier construction, box roof beam prefabrication, box roof beam hoist and mount and leveling processing, specifically include following process:
1) the process of prefabricating the main beam comprises the steps of manufacturing a template, lofting a pedestal and the like, wherein the gradient arrangement and symmetry of each prefabricated part of the main beam caused by longitudinal and transverse slopes of a bridge are required to be paid attention to, meanwhile, the arrangement sizes and the positions of an expansion joint reserved groove, a negative bending moment bundle tensioning groove and a prestressed pipeline (beam end negative bending moment bundle flat pipe is required to be extended outwards for butt joint) are required to be paid attention to, whether the expansion joint, a guardrail, a drain pipe, a support, a bridge deck system and other pre-arranged parts of auxiliary facilities are complete or not is strictly required to be checked before concrete of the main beam is poured, and the pouring can be carried out after no fault is determined;
2) comprehensively considering various factors such as construction procedures, construction period arrangement, environmental influence and the like, ensuring the concrete strength through the experiment, reducing the shrinkage and slow release of the concrete, and ensuring that the sampling and health-preserving conditions of the concrete strength test piece to be filled are matched with the main beam and the beam concrete;
3) when the short T-shaped beam and the T-shaped beam concrete are precast for pouring construction, the beam length and the beam length increment and decrement values are arranged in the uniform section of the midspan section;
4) the abutment back wall is made into an inclined surface according to the longitudinal slope or the anchor sealing end of the upper structure of the abutment end is made into an inclined surface which is vertical to the reference horizontal plane after being in place by considering the influence of the abutment longitudinal slope during prefabrication so as to ensure that the width of the gap between the beam end and the back wall is consistent up and down and ensure that the installation size of the expansion joint and the reserved size of the expansion joint meet the design requirements;
5) for a prestressed structure, prestressed construction should meet technical specifications for highway bridge and culvert construction, a through double-acting jack is adopted for prestressed tension, a jack with a self-anchoring function is adopted for integral tensioning or releasing, channel grouting is carried out after prestressed tendons are tensioned and should be completed within 48h, the end of an anchorage device is timely sealed and protected after grouting is completed, a positive air auxiliary grouting process is adopted for channel grouting, and nondestructive detection or endoscopy is adopted after grouting;
6) suspension casting of box girders:
firstly, the No. 0 segment and the side span cast-in-place segment of the box girder are constructed by adopting a support cast-in-place method, the middle and side span closure segments are constructed by adopting a cast-in-place method on a hanger, the other segments are all cast in a hanging basket suspension manner, a correct casting procedure is required to be established during construction so as to ensure the engineering quality,
secondly, the hanging basket construction process is as follows:
a. before construction, the hanging basket must be assembled and subjected to a weight test to check whether the strength and the rigidity of the hanging basket meet the requirements, and the hanging basket can be formally used after supervision, examination and evaluation;
b. during a hanging basket load test, elastic deformation under corresponding load is measured, so that pre-camber is reasonably set during construction, and the line shape of the box girder is ensured to meet design requirements;
c. after the cradle is in place, the whole equipment, the nodes, the rear anchor system, the front and rear hoisting point systems, the balance system, the brake system, the walking system and the like are comprehensively checked;
d. after the box girder bottom die is installed, measurement is carried out, and whether the central line of the hanging basket is aligned with the central line of the box girder is measured again;
e. the hanging basket is required to observe deformation in time in the pouring process and take effective measures (such as methods of deformation adjustment, pre-deformation and the like) to prevent cracks from being generated among concrete of the box girder sections, and simultaneously, the observation of concrete near a rear lifting point and a front supporting point is also required to be enhanced;
f. unified command, coordination and coordination are needed in the basket hanging process, management is enhanced, and safety is ensured;
thirdly, the structure and the stress of the No. 0 block of the variable cross-section box girder are complex, longitudinal, vertical and transverse prestressed pipelines are concentrated, reinforcing steel bars are dense, the volume of concrete is large, necessary measures are needed to control the influence of concrete hydration heat during pouring in order to ensure the structural strength and prevent harmful cracks from appearing, the position of layering is reasonably determined when layered pouring is adopted, the age difference of each layer of concrete is as small as possible, and the cracking of the concrete caused by the shrinkage difference of each layer of concrete is avoided;
in addition, after the top plate is poured, watering and maintenance inside and outside the No. 0 block piece should be paid attention to practically, ventilation and cooling inside the block piece are enhanced, and the mold is removed in time to avoid cracking of concrete caused by temperature difference between the inside and the outside;
the construction is carried out strictly according to the construction sequence provided by the design, and symmetrical construction is required, wherein the construction comprises that the cantilever casting sections are symmetrical relative to the main pier and the prestressed beams meet the requirement of symmetrical tensioning in the cross section of the box girder as much as possible;
fifthly, the support of the cast-in-place beam section not only needs to meet the strength requirement, but also needs to meet the rigidity requirement, before the concrete box beam is cast formally, a weight test needs to be carried out, the pre-pressing weight is 125% of the weight of the box beam section, so as to ensure safety and eliminate inelastic deformation of the box beam section, and the bottom die elevation and the pre-camber are determined according to the actually measured elastic deformation and the construction control requirement;
when the variable cross-section box girder is constructed, a temporary support system is adopted for the stability and safety of a main pier, the temporary support system consists of a support steel pipe and a prestress system and is a main stressed component in the cantilever construction of the box girder, and when the two cantilevers of the box girder occasionally have asymmetric load action, the temporary support system is an important measure for ensuring the construction safety of the bridge and the stability of the cantilever inclined thin girder; the number, position and number of the steel pipes are determined according to construction safety and construction overturning stability calculation, and participate in structural stress, the size and specification of the supporting steel pipes can be selected by a construction unit, but the strength and rigidity of a supporting system must be ensured;
seventhly, one end of a prestressed steel beam of the temporary support system of the variable-section box beam is embedded in a bearing platform and comprises a pre-embedded P-shaped anchorage device, a corrugated pipe and a spiral rib, the other end of the prestressed steel beam is tensioned and anchored in a box beam bottom plate, and the prestressed steel beam is symmetrically arranged on two sides of the pier and synchronously tensioned; the temporary support dismantling is also balanced, the structure and the appearance are not damaged, the triangular cushion layer of the temporary support system can ensure that the top surface of the I-beam and the bottom plate of the box beam, the prestressed tendon anchor plate is closely attached to the bottom plate, and the triangular cushion layer is synchronously manufactured during the construction of the bottom plate;
during the suspension casting construction of the box girder, construction is carried out according to the principle of symmetry, balance and synchronization, the sizes of all parts of the section of the box girder are strictly guaranteed according to construction specifications, the construction is stopped when strong wind forecast occurs in the construction process of the girder section, unbalanced load is not obtained at two cantilever ends as much as possible, only one side is allowed to be overweight by 20 tons under special conditions, concrete must be cast from the cantilever ends to the direction of a cast block piece when the cast block piece is cast, and vertical cracks are prevented from occurring at the joint surface of new and old concrete; the cantilever casting of the beam section is required to be completed by one-time casting, so that the concrete quality of the beam section is ensured;
ninthly, strictly controlling the age difference of adjacent two concrete pouring to be not more than 20 days under any condition, thoroughly removing floating slurry on the joint surface of new and old concrete, chiseling and cleaning, strictly controlling the water cement ratio, reducing the aggregate temperature, reducing the frictional resistance between the template and the concrete, enhancing the maintenance, controlling the formwork removal time, reducing the influence of concrete shrinkage and hydration heat on the structure, and avoiding the generation of shrinkage and hydration heat cracks;
the construction period of each beam section is required to be not less than 10d at the node, the construction period comprises the steps of arranging hanging baskets, binding steel bars by using vertical molds, pouring concrete and tensioning longitudinal prestressed bundles, and the stress age of the concrete is not less than 10 days;
7) mounting a main beam:
a. the continuous one-connection construction sequence of the structure is as follows: prefabricating a main beam → erecting a beam, pouring a pier top cast-in-place continuous section and a flange plate, wet joints of a diaphragm plate, tensioning a middle pier top T beam hogging moment steel beam → forming a continuous system → pouring bridge deck pavement concrete → installing guardrails, arranging a bridge deck waterproof withered layer after nine treatments of bridge deck polishing, pouring asphalt concrete pavement, installing accessory facilities → forming a bridge;
b. the precast beam adopts a hoisting method of arranging hoisting holes to penetrate and bundle the beam bottom, the precast beam is careful to keep the transverse stability of the beam body in the processes of transportation, lifting and the like, effective measures are taken to strengthen the transverse temporary support after the precast beam is erected, and cast-in-place continuous section connecting steel bars and only edge plates and diaphragm plate seam steel bars are connected so as to increase the stability and the integrity of the beam body, and the next hole cannot be erected under the condition that the previous hole is not transversely connected;
c. the bridge erection adopts a bridge erecting machine for hoisting, the bridge can be transported on the bridge erecting machine after only the connection of the cross plates between the main girders and the concrete pouring of the wet joints of the grab plates reach 90% of the design grade of the concrete strength and pressure diffusion measures are taken, the bridge erecting machine must be heavy and fall on the beam ribs when the bridge erecting machine runs on the bridge, a construction unit carries out construction load checking calculation on the main girders according to the model of the bridge erecting machine, and the construction can be carried out after the checking calculation is passed;
d. after the cubic strength and elastic modulus of the concrete at the cast-in-place section of the pier top reach 90% of the design grade, tensioning the pier top continuous bundle;
thirdly, reinforcing the old bridge:
prestressing tendons are adopted to apply prestress to the bridge piers, and permanent anchor ears are arranged on the side walls of the bridge piers for bonding and reinforcing; carrying out impact tumor removal, chiseling and disordered steel bar cutting treatment on the damaged bridge deck, and paving steel fiber concrete on the bridge deck to realize bridge deck pavement and reinforcement;
fourthly, widening the bridge deck:
1) the upper structure is as follows: in order to ensure the consistency of the rigidity of the hollow slabs of the new bridge and the old bridge, the load is effectively distributed in the transverse bridge direction, the widened part of the hollow slab is still constructed according to the original design, the original designed hollow slab is checked again, and the bearing capacity of the hollow slab is determined to meet the design load requirement;
2) in order to prevent the bridge deck from cracking, double layers of reinforcing mesh are additionally paved at the joint part of the new bridge and the old bridge so as to ensure the safety of the bridge structure;
3) considering that the influence on the stress of the bent cap caused by the inconsistent settlement of the new bridge and the old bridge is adverse, when a scheme is formulated, the bent cap of the new bridge and the old bridge is subjected to disconnection treatment;
4) when the old bridge is integrally widened, the arrangement of the bridge and the hollow slab of the widened part meets the following requirements:
the upper structures of the new bridge and the old bridge are matched as much as possible, so that the rigidity of the new widened bridge is basically the same as that of the original bridge, and longitudinal cracks are prevented from being generated due to overlarge deflection difference generated at the joint part of the new bridge and the old bridge because of different rigidity of the new bridge and the old bridge;
secondly, under the condition that the lower part structure of the new bridge meets the stress requirement, a new bridge pile foundation cannot be poured near the original old bridge pile, the pile distance between the new bridge and the old bridge is increased as much as possible, and the influence of the construction process on the foundation structure of the old bridge is prevented;
the elevation of the new bridge is basically consistent with that of the old bridge, and the direct connection of the gradient is noticed, so that the structural stress and the driving on the bridge are facilitated;
fifthly, transversely splicing the bridge:
when the bridge to the case roof beam structure transversely merges, be used for bridge cross section, ramp, pivot frequently, adopt articulated mode to carry out transversely to the case roof beam structure and merge, during specific operation: after the flange concrete at the joint is poured, sawing seams are formed on the top surface of the flange concrete, flexible materials are filled, wood strips or rubber strips are embedded at the bottom of the flange concrete, and the flanges are connected through reinforcing steel bars to form a flexible hinge structure which can not transmit bending moment;
sixthly, double-beam butt joint:
firstly, a new bridge and an old bridge which need to be butted adopt a steel bar pouring connection structure, specifically, rectangular notches (1) are arranged at the opposite positions of the top surfaces of two box girders, a gap between the two box girders and the two rectangular notches (1) form a T-shaped cavity structure, holes are drilled on the side wall and the bottom wall of the rectangular notch (1), V-shaped suspension loop thin rings (2) are inserted and connected through glue, a plurality of groups of V-shaped suspension loop thin rings (2) are connected with horizontal thin supporting steel bars (3) in a penetrating manner, the thin supporting steel bars (3) are contacted with a plurality of groups of transverse steel bar rings (4) which are arranged in parallel, and a row of straight steel bars I (5) are respectively bound at the inner walls of the top and the bottom of the plurality of groups of transverse steel bar rings (4);
drilling holes in two side walls of a gap between two box girders, inserting V-shaped lug coarse rings (6) through glue, connecting a plurality of groups of V-shaped lug coarse rings (6) with horizontal coarse support steel bars (7) in a penetrating manner, binding horizontal straight steel bars II (8) between two groups of adjacent coarse support steel bars (7), binding vertical straight steel bars III (9) in the middle of a plurality of straight steel bars II (8) positioned on the same vertical plane, and mutually perpendicular the coarse support steel bars (7), the straight steel bars II (8) and the straight steel bars III (9) in pairs;
vertical reinforcing steel bars (10) are bound on the outer sides of the coarse support reinforcing steel bars (7), the upper portions of the vertical reinforcing steel bars (10) are bound and fastened with partial straight reinforcing steel bars I (5), the partial straight reinforcing steel bars I (5) are located on the vertical reinforcing steel bars (10), and the straight reinforcing steel bars I (5) located in the left middle and the right middle are bound and fastened with the transverse reinforcing steel bars (4) and the straight reinforcing steel bars III (9) at the same time;
the specific operation is as follows: drilling and fixedly connecting V-shaped suspension loop thin rings (2) and V-shaped suspension loop thick rings (6) to enable a plurality of groups of V-shaped suspension loop thin rings (2) or V-shaped suspension loop thick rings (6) to form an equidistant array respectively, connecting the thin supporting steel bars (3) in place in a penetrating manner, and binding the transverse steel bar rings (4) to the thin supporting steel bars (3); then suspending the vertical reinforcing steel bar rings (10) in a gap between the two box girders, connecting the coarse supporting reinforcing steel bars (7) in place in a penetrating manner and binding the coarse supporting reinforcing steel bars with the vertical reinforcing steel bar rings (10), binding the straight reinforcing steel bars II (8) to the coarse supporting reinforcing steel bars (7), and sequentially binding the straight reinforcing steel bars III (9) to the middle parts of the straight reinforcing steel bars II (8) and the transverse reinforcing steel bar rings (4); binding all the straight steel bars I (5) into the transverse steel bar rings (4), binding one part of the straight steel bars I (5) with the vertical steel bar rings (10), and binding the other part of the straight steel bars I (5) with the straight steel bars III (9); after the binding is finished, the sealing template is poured, after the drying, the maintenance is carried out, namely the double-beam butt joint process of the T-shaped cavity structure is finished, and a bridge deck pavement layer (11) of steel fiber concrete is paved on the upper surface of the T-shaped cavity structure;
seventhly, heightening the bridge deck:
for some butt-jointed bridges, because the gradient is too high, the heightening treatment is needed for the bridge deck which is too low, the whole heightening project of the bridge usually adopts a broken column jacking scheme, if the whole uplifting height is not high, a method of covering a beam on an original column can be adopted, generally, when the navigation clearance does not meet the requirement, or when the original route is reconstructed and lifted, the old bridge needs to be lifted, and under the condition that the original bridge can meet the current use at all, in order to save the investment and reduce the manufacturing cost, the construction period can be greatly shortened by adopting the scheme;
eighthly, dismantling the old bridge:
the old bridge dismantling comprises dismantling of the whole upper structure and the lower structure, the bridge dismantling safety is very important, and a detailed construction scheme and construction organization are required to be made before construction, so that the bridge dismantling safety is ensured;
the old bridge removal should follow the principle: firstly, building and then dismantling, and then building and dismantling; according to the principle of symmetry and uniformity, for a rigid frame arch bridge with high thrust, uniform unloading is required to be realized in order to prevent overlarge displacement deformation in the bridge dismantling process, wherein a midspan is firstly carried out, then a side span is carried out, a solid abdomen section is firstly carried out, and then an arch leg section is symmetrically dismantled from top to bottom layer by layer; when the cast-in-place pile is involved, chiseling the pile to be 2 meters below the river elevation;
ninthly, paving bridge deck and post-processing:
after the main beam structures of all the bridges are finished, the guardrails, the electric power facility pipelines and the drainage structures are laid, and then continuous paving is adopted to perform paving, vibrating, joint cutting and maintaining, so that the bridge reconstruction process is finished.
2. The box girder type bridge reconstruction construction method according to claim 1, wherein in the sixth step, the pouring of the mold sealing plate in the double-girder butt joint is performed by perforating two ends of the coarse support steel bar (7) and extending the mold, after the pouring molding, the extending two ends of the coarse support steel bar (7) are additionally provided with anchor plates, and a stay cable is installed through an anchor and a clamping piece to serve as a prestressed support, so that the function of cable-stayed support is realized.
3. The improvement construction method of an Box girder bridge according to claim 1, wherein the inner walls of the T-shaped cavity structures in the sixth step and the butt joint of the double girders are all subjected to roughening treatment in advance, so that concrete pouring and bonding are facilitated.
4. The method for reconstructing and constructing an extra girder bridge according to claim 1, wherein in the sixth step, gaps are reserved between two sides of the outer ring of the vertical steel reinforcement ring (10) in the double girder butt joint and the side walls of the two extra girders, so that concrete can be poured into the gaps, and the problem that the vertical steel reinforcement ring (10) is in direct contact with the extra girders to cause poor adhesion is avoided.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114164747A (en) * | 2021-12-21 | 2022-03-11 | 上海市政工程设计研究总院（集团）有限公司 | New and old structure collaborative stress structure for bridge widening |
| CN115369707A (en) * | 2022-09-19 | 2022-11-22 | 中铁大桥局集团第一工程有限公司 | Construction method for ballastless track on long-connection large-span railway steel bridge |
| CN117127483A (en) * | 2023-11-02 | 2023-11-28 | 江苏水工建设集团有限公司 | Modularized construction bridge structure and construction process |
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| CN210395128U (en) * | 2019-03-01 | 2020-04-24 | 中国建筑股份有限公司 | Hollow core plate beam connection structure in bridge widening |
| CN211472128U (en) * | 2019-10-16 | 2020-09-11 | 中铁工程服务有限公司 | Continuity combination beam |
| CN114457666A (en) * | 2022-01-25 | 2022-05-10 | 江西省润邦工程技术研究有限公司 | Be applied to assembled transverse connection structure of little case roof beam |
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| JPH09203011A (en) * | 1996-01-25 | 1997-08-05 | East Japan Railway Co | Reconstruction work of short-span over-road bridge or overbridge into long-span bridge |
| CN210395128U (en) * | 2019-03-01 | 2020-04-24 | 中国建筑股份有限公司 | Hollow core plate beam connection structure in bridge widening |
| CN211472128U (en) * | 2019-10-16 | 2020-09-11 | 中铁工程服务有限公司 | Continuity combination beam |
| CN114457666A (en) * | 2022-01-25 | 2022-05-10 | 江西省润邦工程技术研究有限公司 | Be applied to assembled transverse connection structure of little case roof beam |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114164747A (en) * | 2021-12-21 | 2022-03-11 | 上海市政工程设计研究总院（集团）有限公司 | New and old structure collaborative stress structure for bridge widening |
| CN114164747B (en) * | 2021-12-21 | 2023-11-03 | 上海市政工程设计研究总院（集团）有限公司 | New and old structure cooperative stress structure for bridge widening |
| CN115369707A (en) * | 2022-09-19 | 2022-11-22 | 中铁大桥局集团第一工程有限公司 | Construction method for ballastless track on long-connection large-span railway steel bridge |
| CN115369707B (en) * | 2022-09-19 | 2024-05-14 | 中铁大桥局集团第一工程有限公司 | Construction method for ballastless track on long-joint large-span railway steel bridge |
| CN117127483A (en) * | 2023-11-02 | 2023-11-28 | 江苏水工建设集团有限公司 | Modularized construction bridge structure and construction process |
| CN117127483B (en) * | 2023-11-02 | 2024-06-04 | 江苏水工建设集团有限公司 | Modularized construction bridge structure and construction process |
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