Summary of the invention
The purpose of this invention is to provide a kind of new post-tensioned method prestressed concrete box beam whole opening prefabricated construction method, this construction method is applicable to 32m/900t level large span, the whole opening prefabricated construction of large-tonnage prestressed concrete box girder in the special line for passenger trains.
The technical solution adopted for the present invention to solve the technical problems is:
Post-tensioned method prestressed concrete box beam whole opening prefabricated construction method, its technological process as shown in Figure 1, key step comprises:
(1) template, reinforcing bar and built-in fitting etc. are installed:
This step mainly comprises sequentially: trimming bed die, adjustment side form, erection support plate and anti-fall beam slab, installation withdrawing sebific duct, lifting main body reinforcing bar, mounting rail body built-in fitting, lifting internal mold, installation end mould, lifting surfacing steel bar, the installation of bridge floor built-in fitting etc.;
(2) beam body concrete (beam body concrete) placing, beam body concrete steam-cured (or natural curing);
(3) form removal:
This step mainly comprises sequentially: withdrawing sebific duct, dismounting end mould, dismounting internal mold, loose side form etc.;
(4) stretch-draw:
This step mainly comprises sequentially: steel strand, the pre-stretch-draw of case beam, case beam initial tensioning, move beam to the whole stretch-draw of beam strorage area, concrete curing, case beam etc.;
(5) postorder construction:
This step mainly comprises sequentially: cut silk, pipeline pneumatic mortar, bridge sealing off and covering anchorage, maintenance, the appearance of case beam inspection, box beam erection, making watertight composition, construction protective layer, maintenance etc.;
Wherein:
Described main body reinforcing bar and bridge floor reinforcing bar all adopt concentrates pre-bundle, integral hoisting technology, i.e. the processing of case beam steel (comprising main body reinforcing bar and bridge floor reinforcing bar) is all finished in the reinforcing bar workshop, carries out colligation then on loose tool; Install for making things convenient for internal mold, divide two stages to carry out the colligation of case beam steel: the phase I, the main muscle that earlier beam body master muscle (comprise web and base plate reinforcing bar, contain a seat board, anti-fall beam slab, drilling sebific duct) coexisted is pricked in advance and is implemented pre-the bundle on the frame, and the bridge floor reinforcing bar is then pricked in advance on the frame at special bridge floor and pricked in advance; Second stage, treat main muscle and internal mold hoisted in position after, adopt straddle truck that bridge floor reinforcing bar and beam body master muscle assembly unit colligation is in place.
At the bottom of the above-mentioned case beam, web reinforcement carries out colligation and can adopt following method on loose tool: the vertical and horizontal bar space is according to Design Requirement Drawing, on the limb of angle steel vertical plane, cut the groove of 50 * 30mm, reinforcing bar just in time is stuck in the groove, to guarantee the laid reinforcement binding quality; For guaranteeing that the vertical and horizontal reinforcing bar position correctly reaches the allowable error of the satisfied regulation of protective layer thickness of both sides web reinforcement; can weld one 75 * 6mm angle steel respectively on the base, two outsides of loose tool tool; make a retaining with its vertical limb; when colligation; the crotch of horizontal bar and web stirrup are adjacent to this limb back of the body, neat with the tram that guarantees reinforcing bar and outside reinforcing bar.
Above-mentioned box girder bridge face reinforcing bar carries out colligation on loose tool can adopt following method: the main body of loose tool is welded with 50 * 30mm square steel; Because the cross sectional shape of bridge floor reinforcing bar has determined the bridge floor reinforcing bar to be not suitable for operating in the plane, therefore, cross sectional shape according to the bridge floor reinforcing bar, the supporting leg that can add weldering 500mm to 800mm varying length in the bottom of colligation loose tool, make the operation plane just in time about 900mm, both met design requirement, again handled easily; At two lateral surfaces of loose tool, by the height of wing plate (being floorings) reinforcing bar, the contour short square steel of weldering that keeps at a certain distance away, the end face of short square steel promptly is the reinforcing bar height; Pressing the short square steel that the weldering of wing plate reinforcing bar design grade does not highly wait at the loose tool two ends, weld one elongated (isometric with bridge floor) reinforcing bar at the top of short square steel, promptly is the height of bridge floor top layer reinforcing bar; The control of bridge floor bar spacing can be adopted following method: reinforcing bar makes " U " shape card with Φ 5mm high tensile steel wire on loose tool, be welded in the relevant position of loose tool then by the requirement of drawing design pitch, when colligation reinforcing bar just in time is stuck in " U " shape card.
For contraction crack appears in prevention beam body concrete, described stretch-draw step adopts three tensioning process, that is: pre-stretch-draw, initial tensioning and whole stretch-draw; Pre-tensioning process wherein is meant: for the control cabinet beam produces Temperature Cracks in early days, and " the early stage pre-stretch-draw of prestressing force band mould " technology of under low-intensity, carrying out partial prestressing stretch-draw of taking, that is: to the pre-stretch-draw steel bundle that designs on the design drawing and initial tensioning bundle etc., when concrete strength with play mould and reach 50% and 50% of design load respectively and carry out part steel Shu Zhangla when above, tension stress is controlled by design load 55%; When concrete strength with play the 80% initial tensioning partial prestressing bundle that mould reaches design load respectively, tension stress is by design load 70% control, after finishing the case beam is carried to and deposits the beam pedestal; Treat concrete strength and play to carry out other prestressing tendon stretch-draw when mould all reaches design load, and pre-stretch-draw and initial tensioning Shu Jinhang benefit are moved to the design proof stress.
Box girder inner formwork in the above-mentioned post-tensioned method prestressed concrete box beam whole opening prefabricated construction method, adopt following hydraulic internal mold system:
This system comprises standard paragraphs (beam body interlude), variable cross-section section (beam body web thickening section) and aperture section, and template is consistent with case overall size in the case beam; Standard paragraphs and variable cross-section section are formed by template system, frame system and frame (containing support) and hydraulic system, and the aperture section is made up of template system and frame system and frame (containing support); Wherein, template is a bulk punching block composed structure, divides counterdie, Bian Mo and three parts of backform; Variable cross-section section and aperture section are the bulk combined steel, can be formed by 14# worker's steel, 14# channel-section steel, 6~12mm steel plate assembly welding; Frame system and frame comprises vehicle frame truss, traveling support and travelling wheel, can by shaped steel [20, [14, ∠ 14 * 10 and 10,16mm steel plate assembly welding form;
It at first is internal mold merogenesis assembly unit on platform for lining in advance that internal mold is installed, and is coupled to an integral body by joint then, in place with two straddle truck integral hoistings; Internal mold integral body is hung in the pedestal upper base web reinforcement skeleton, the screw rod strut on the chassis is supported in (this preformed hole is made case beam base plate spilled water hole) in the preformed hole, internal mold is stablized be installed on the bed die;
Hydraulic internal mold adopts the segmentation method for dismounting when removing, its key step is as follows: (1), take off all struts, start lower mold oil cylinder, pack up the both sides counterdie; (2), start the dual-side mould oil cylinder, pack up the limit mould; (3), start vertical oil cylinder, fall backform; (4), screw out the spiral push rod, formwork integral drops on the track, pulls out the case beam.
Case beam external mold (side form) in the above-mentioned post-tensioned method prestressed concrete box beam whole opening prefabricated construction method, adopt following external mold (side form) system:
This system is made up of bed die, outer side form and end mould, is bulk punching block composed structure; Built-in fitting welding on bed die and the beam making bench is fixing, and outer side form adopts primary and secondary iron wedge to be connected with the wedging of bed die crossbeam, and the end mould is connected with bolt with the end, side form;
The bed die system is made up of crossbeam, longitudinal stiffener and panel; For strengthening segment structure, can adopt thickness is vertical rib of panel, 14# double flute steel and 20# double flute steel combination beam crossbeam about 20mm to bed die near the bearing two ends; The middle part be general segment structure, and can adopt thickness is that panel, 14# channel-section steel about 10mm indulged rib and 16# double flute steel combination beam; Outer side form can be that panel, longitudinal stiffener (10#, 12# worker's steel) and keel truss (16# worker's steel and channel-section steel combination) about 8mm formed by thickness; It is panel, 16# worker's steel rib and 20# channel-section steel frame in length and breadth about 10mm that the end mould can adopt thickness; Because the connecting reinforcement that the case beam stretches out in middle pier side is more, for being convenient in demoulding, this side mould can adopt little block structure, and the Side Template of the pier side of keeping to the side adopts bulk punching block composed structure.
Beam body concrete in the above-mentioned post-tensioned method prestressed concrete box beam whole opening prefabricated construction method (beam body concrete) placing step, because case beam concrete design quantity is big, particularly the 32m beam reaches 318m
3, be the shortening concreting time, the arrangement and method for construction that system beam field by using concrete centralized mixing, pipeline pumping are built, that is:
Adopt the independently stirring of three covers, casting system configuration, every cover system adopts the automatic mixing plant+concrete pump of concrete+boom+equipment that vibrates, and the mode that layering is passed is continuously built to the incremental construction method in centre by two ends, one-shot forming is built thickness<30cm for every layer; Three covers stir, casting system starts by cover, and wherein two covers are responsible for the one end concreting of case beam, another set of responsible other end concreting; Oblique segmentation is adopted in concreting, the continuous placing of the mode of horizontal slice, the placing order is according to marking among Fig. 2 1., 2., 3., 4. sequencing, cloth carries out synchronously symmetrically and evenly from case beam two coxostermums earlier, build web and base plate junction concrete earlier, build web concrete again, when the both sides web concrete is poured into top board face binding site, use the concreting hole blanking teeming underplate concrete of reserving from the internal mold end face instead, and in time shakeout, supply, vibrate, control absolute altitude well, reach designing requirement, build top board (floorings) concrete at last.
Should note in the beam body concrete placing step: when building the both sides web concrete, adopt synchronous symmetry to build web concrete, prevent both sides concrete height great disparity, cause internal mold skew or other adverse consequences; Bridge deck concrete is also built from two ends to middle contiguous segmentation, about 2 meters every section, receives slurry in order to the surface and touches face; The beam body concrete is built and can be adopted the moulding of vibrating of plug-in type vibrating head, and is aided with that side is shaken and the end shakes, to guarantee concrete compaction; Build in the process and to note strengthening vibrating of case beam-ends head, chamfering and reinforcing bar dense part, emphasis strengthen corner, web and base plate the interface place vibrate and the base plate absolute altitude is controlled; Bridge deck concrete adopts the plate vibration trowelling machine in time to catch up with pressure, floating after being poured into designed elevation, and it is floating in case crackle makes bridge floor reach smooth to carry out receiving slurry the second time to bridge floor before concrete initial set, and draining is unobstructed.
On the other hand, for satisfying the needs that the case beam adapts to 100 years durability, the inventor is by carrying out a large amount of service checks to raw material, thousands of assembly composition and division in a proportion tests, and the on-the-spot temporary project of combination has been carried out engineer testing repeatedly, develop the employing conventional raw materials, common process, adding coal ash, ore deposit quarrel powder as additive and efficient additive, the durable concrete of preparing through ratio optimization of case beam C50 high-performance with high-durability and works fine, as the used concrete preferred version of post-tensioned method prestressed concrete box beam whole opening prefabricated construction method central sill body of the present invention (also can adopt present beam bridge prefabricated in concrete commonly used), its composition and optimum weight part proportioning are:
262 parts of cement, 140 parts in slag, 68 parts in flyash, 742 parts in sand,
1068 parts in stone, 3.9 parts of additives, 141 parts in water.
Additive wherein is a high efficiency water reducing agent, as: go up the LEX-9H liquid water reducer that Haicheng City sincere building materials Co., Ltd produces, or the TH-2A powder water reducer of railway construction research institute of institute of iron section production etc.
Compared with prior art, the invention has the beneficial effects as follows:
Post-tensioned method prestressed concrete box beam whole opening prefabricated construction method of the present invention is at the technological difficulties in large span, the whole opening prefabricated work progress of large-tonnage prestressed concrete box girder such as 32m/900t level in the special line for passenger trains, adopt the corresponding techniques means to solve, thereby obtain satisfied technique effect, the prestressed concrete box girder that makes adhered to specification:
(1) in the post-tensioned method prestressed concrete box beam whole opening prefabricated construction method of the present invention, main body reinforcing bar and bridge floor reinforcing bar all adopt pre-bundle, the integral hoisting technology concentrated, this technology reinforcing bar pricks in advance that quality is good, and it is accurate that reinforcing bar is pricked the position in advance, and spacing and cover to reinforcement adhere to specification; The framework of steel reinforcement distortion when lifting of end web reinforcement and bridge floor reinforcing bar is little, lifting and easy for installation, efficient height;
(2) post-tensioned method prestressed concrete box beam whole opening prefabricated construction method of the present invention has adopted the hydraulic internal mold construction technology, and this technology has advantages such as strong operability, safe in utilization, efficient, good reliability; Make the interior case of the case beam that makes bright and clean, overall size is good, meets design requirement;
(3) tensioning process of post-tensioned method prestressed concrete box beam whole opening prefabricated construction method of the present invention has adopted the pre-stretching construction technology of band mould, can avoid the beam body infant cracking to occur, can satisfy bridge structure life requirement in 100 years;
(4) in the post-tensioned method prestressed concrete box beam whole opening prefabricated construction method of the present invention, the arrangement and method for construction that beam body concrete placing step has adopted concrete centralized mixing, pipeline pumping to build, adopt the independently stirring of three covers, casting system configuration, adopt the continuous placing of mode of oblique segmentation, horizontal slice, by two ends to the incremental construction in centre, one-shot forming, can shorten the concreting time, and early age strength of concrete is low, avoid the beam body infant cracking to occur, can satisfy bridge structure life requirement in 100 years.
The specific embodiment
The present invention is described in further detail below in conjunction with the specific embodiment.
But this should be interpreted as that the scope of the above-mentioned theme of the present invention only limits to following embodiment.
Embodiment
The technological process of present embodiment post-tensioned method prestressed concrete box beam whole opening prefabricated construction method as shown in Figure 1, its key step comprises:
(1) template, reinforcing bar and built-in fitting etc. are installed:
This step mainly comprises sequentially: trimming bed die, adjustment side form, erection support plate and anti-fall beam slab, installation withdrawing sebific duct, lifting main body reinforcing bar, mounting rail body built-in fitting, lifting internal mold, installation end mould, lifting surfacing steel bar, the installation of bridge floor built-in fitting etc.
In this step:
Main body reinforcing bar and bridge floor reinforcing bar all adopt concentrates pre-bundle, integral hoisting technology, i.e. the processing of case beam steel (comprising main body reinforcing bar and bridge floor reinforcing bar) is all finished in the reinforcing bar workshop, carries out colligation then on loose tool; Install for making things convenient for internal mold, divide two stages to carry out the colligation of case beam steel: the phase I, the main muscle that earlier beam body master muscle (comprise web and base plate reinforcing bar, contain a seat board, anti-fall beam slab, drilling sebific duct) coexisted is pricked in advance and is implemented pre-the bundle on the frame, and the bridge floor reinforcing bar is then pricked in advance on the frame at special bridge floor and pricked in advance; Second stage, treat main muscle and internal mold hoisted in position after, adopt straddle truck that bridge floor reinforcing bar and beam body master muscle assembly unit colligation is in place;
At the bottom of the case beam, web reinforcement adopts following method when carrying out colligation on loose tool: the vertical and horizontal bar space is cut the groove of 50 * 30mm according to Design Requirement Drawing on the limb of angle steel vertical plane, reinforcing bar just in time is stuck in the groove, to guarantee the laid reinforcement binding quality; For guaranteeing that the vertical and horizontal reinforcing bar position correctly reaches the allowable error of the satisfied regulation of protective layer thickness of both sides web reinforcement, one 75 * 6mm angle steel is welded on base, two outsides at the loose tool tool respectively, make a retaining with its vertical limb, when colligation, the crotch of horizontal bar and web stirrup are adjacent to this limb back of the body, neat with the tram that guarantees reinforcing bar and outside reinforcing bar;
The box girder bridge face reinforcing bar adopts following method when carrying out colligation on loose tool: the main body of loose tool is welded with 50 * 30mm square steel; Because the cross sectional shape of bridge floor reinforcing bar has determined the bridge floor reinforcing bar to be not suitable for operating in the plane, therefore, cross sectional shape according to the bridge floor reinforcing bar, the supporting leg that adds weldering 500mm to 800mm varying length in the bottom of colligation loose tool, make the operation plane just in time about 900mm, both met design requirement, again handled easily; At two lateral surfaces of loose tool, by the height of wing plate (being floorings) reinforcing bar, the contour short square steel of weldering that keeps at a certain distance away, the end face of short square steel promptly is the reinforcing bar height; Pressing the short square steel that the weldering of wing plate reinforcing bar design grade does not highly wait at the loose tool two ends, weld one elongated (isometric with bridge floor) reinforcing bar at the top of short square steel, promptly is the height of bridge floor top layer reinforcing bar; Bridge floor bar spacing control employing method is: reinforcing bar makes " U " shape card with Φ 5mm high tensile steel wire on loose tool, be welded in the relevant position of loose tool then by the requirement of drawing design pitch, when colligation reinforcing bar just in time is stuck in " U " shape card.
Box girder inner formwork adopts following hydraulic internal mold system:
This system comprises standard paragraphs (beam body interlude), variable cross-section section (beam body web thickening section) and aperture section, and template is consistent with case overall size in the case beam; Standard paragraphs and variable cross-section section are formed by template system, frame system and frame (containing support) and hydraulic system, and the aperture section is made up of template system and frame system and frame (containing support); Wherein, template is a bulk punching block composed structure, divides counterdie, Bian Mo and three parts of backform; Variable cross-section section and aperture section are the bulk combined steel, are formed by 14# worker's steel, 14# channel-section steel, 6~12mm steel plate assembly welding; Frame system and frame comprises vehicle frame truss, traveling support and travelling wheel, by shaped steel [20, [14, ∠ 14 * 10 and 10,16mm steel plate assembly welding form;
It at first is internal mold merogenesis assembly unit on platform for lining in advance that internal mold is installed, and is coupled to an integral body by joint then, in place with two straddle truck integral hoistings; Internal mold integral body is hung in the pedestal upper base web reinforcement skeleton, the screw rod strut on the chassis is supported in (this preformed hole is made case beam base plate spilled water hole) in the preformed hole, internal mold is stablized be installed on the bed die;
Hydraulic internal mold adopts the segmentation method for dismounting when removing, its key step is as follows: (1), take off all struts, start lower mold oil cylinder, pack up the both sides counterdie; (2), start the dual-side mould oil cylinder, pack up the limit mould; (3), start vertical oil cylinder, fall backform; (4), screw out the spiral push rod, formwork integral drops on the track, pulls out the case beam.
Case beam external mold (side form) adopts following external mold (side form) system:
This system is made up of bed die, outer side form and end mould, is bulk punching block composed structure; Built-in fitting welding on bed die and the beam making bench is fixing, and outer side form adopts primary and secondary iron wedge to be connected with the wedging of bed die crossbeam, and the end mould is connected with bolt with the end, side form;
The bed die system is made up of crossbeam, longitudinal stiffener and panel; For strengthening segment structure, employing thickness is vertical rib of panel, 14# double flute steel and the 20# double flute steel combination beam crossbeam about 20mm to bed die near the bearing two ends; The middle part is general segment structure, and employing thickness is vertical rib of panel, 14# channel-section steel and the 16# double flute steel combination beam about 10mm; Outer side form is that panel, longitudinal stiffener (10#, 12# worker's steel) and keel truss (16# worker's steel and channel-section steel combination) about 8mm formed by thickness; It is panel, 16# worker's steel rib and 20# channel-section steel frame in length and breadth about 10mm that the end mould adopts thickness; Because the connecting reinforcement that the case beam stretches out in middle pier side is more, for being convenient in demoulding, this side mould adopts little block structure, and the Side Template of the pier side of keeping to the side adopts bulk punching block composed structure.
(2) beam body concrete (beam body concrete) placing, beam body concrete are steam-cured.
Because case beam concrete design quantity is big, particularly the 32m beam reaches 318m
3, be the shortening concreting time, the arrangement and method for construction that system beam field by using concrete centralized mixing, pipeline pumping are built, that is:
Adopt the independently stirring of three covers, casting system configuration, every cover system adopts the automatic mixing plant+concrete pump of concrete+boom+equipment that vibrates, and the mode that layering is passed is continuously built to the incremental construction method in centre by two ends, one-shot forming is built thickness<30cm for every layer; Three covers stir, casting system starts by cover, and wherein two covers are responsible for the one end concreting of case beam, another set of responsible other end concreting; The continuous placing of the mode of oblique segmentation, horizontal slice is adopted in concreting, placing order according to mark among Fig. 2 1., 2., 3., 4. sequencing, cloth carries out synchronously symmetrically and evenly from case beam two coxostermums earlier, build web and base plate junction concrete earlier, build web concrete again, when the both sides web concrete is poured into top board face binding site, use the concreting hole blanking teeming underplate concrete of reserving from the internal mold end face instead, and in time shakeout, supply, vibrate, control absolute altitude well, reach designing requirement, build concrete roof at last;
In the beam body concrete placing process, when building the both sides web concrete, adopt synchronous symmetry to build web concrete, prevent both sides concrete height great disparity, cause internal mold skew or other adverse consequences; Bridge deck concrete is also built from two ends to middle contiguous segmentation, about 2 meters every section, receives slurry in order to the surface and touches face; The beam body concrete is built and is adopted the moulding of vibrating of plug-in type vibrating head, and is aided with that side is shaken and the end shakes, to guarantee concrete compaction; Build in the process and to strengthen vibrating of case beam-ends head, chamfering and reinforcing bar dense part, emphasis strengthen corner, web and base plate the interface place vibrate and the base plate absolute altitude is controlled; Bridge deck concrete adopts the plate vibration trowelling machine in time to catch up with pressure, floating after being poured into designed elevation, and it is floating in case crackle makes bridge floor reach smooth to carry out receiving slurry the second time to bridge floor before concrete initial set, and draining is unobstructed.
On the other hand, for satisfying the needs that the case beam adapts to 100 years durability, adopt the durable concrete of case beam C50 high-performance of following composition and weight portion proportioning to carry out the placing of beam body:
262 parts of cement, 140 parts in slag, 68 parts in flyash, 742 parts in sand,
1068 parts in stone, 3.9 parts of additives, 141 parts in water.
Additive wherein is the LEX-9H liquid water reducer that last Haicheng City sincere building materials Co., Ltd produces.
(3) form removal:
This step mainly comprises sequentially: withdrawing sebific duct, dismounting end mould, dismounting internal mold, loose side form etc.
(4) stretch-draw:
This step mainly comprises sequentially: steel strand, the pre-stretch-draw of case beam, case beam initial tensioning, move beam to the whole stretch-draw of beam strorage area, concrete curing, case beam etc.
For contraction crack appears in prevention beam body concrete, this stretch-draw step adopts three tensioning process, that is: pre-stretch-draw, initial tensioning and whole stretch-draw; Pre-tensioning process wherein is meant " the early stage pre-stretch-draw of the prestressing force band mould " technology of carrying out partial prestressing stretch-draw under low-intensity, that is: when concrete strength with play mould and reach 50% and 50% of design load respectively and carry out part steel Shu Zhangla when above, tension stress is controlled by design load 55%; When concrete strength with play the 80% initial tensioning partial prestressing bundle that mould reaches design load respectively, tension stress is by design load 70% control, after finishing the case beam is carried to and deposits the beam pedestal; Treat concrete strength and play to carry out other prestressing tendon stretch-draw when mould all reaches design load, and pre-stretch-draw and initial tensioning Shu Jinhang benefit are moved to the design proof stress.
(5) postorder construction:
This step mainly comprises sequentially: cut silk, pipeline pneumatic mortar, bridge sealing off and covering anchorage, maintenance, the appearance of case beam inspection, box beam erection, making watertight composition, construction protective layer, maintenance etc.