CN104452591B - A kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building - Google Patents

A kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building Download PDF

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CN104452591B
CN104452591B CN201410551334.8A CN201410551334A CN104452591B CN 104452591 B CN104452591 B CN 104452591B CN 201410551334 A CN201410551334 A CN 201410551334A CN 104452591 B CN104452591 B CN 104452591B
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template
concrete
construction
steel
adopts
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CN201410551334.8A
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CN104452591A (en
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苏春生
丁浩航
何十美
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中铁建大桥工程局集团第五工程有限公司
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    • EFIXED CONSTRUCTIONS
    • E01CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01DCONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
    • E01D21/00Methods or apparatus specially adapted for erecting or assembling bridges

Abstract

The present invention relates to a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building, comprise successively step: the installation → pre-pressing bracket → precompressed of bracket basis → support installation → end template unloads → adjusts the reinforcing bar of bed die absolute altitude → base plate and web and installed under prestressing → side template and inner formword and installs → build the reinforcing bar of base plate and web concrete → dismounting inner formword → top board and installed under prestressing → build top plate concrete → health 7 days → stretch-draw → hole path pressure grouting → support dismounting → end-blocking. The present invention passes through construction procedure and the execution conditions in Optimizing construction process, thereby can shorten construction period, reduces construction cost, reduces the probability that occurs security incident, has improved integral construction quality.

Description

A kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building
Technical field
The present invention relates to construction technology, specifically refer to a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building.
Background technology
Cast-in-situ box girder is the one of science of bridge building central sill, and inside is hollow shape, and there is the edge of a wing both sides, top, similar chest, thereby gain the name, point single case, many casees etc. The case beam of reinforced concrete structure is divided into prefabricated case beam and cast-in-situ box girder, and the case beam prefabricated in independent place can set up in conjunction with Bridge Erector after bottom engineering completes, and can accelerate project progress, save the duration; Cast-in-situ box girder is used for Large Scale and Continuous bridge. Common dividing with material at present, mainly contains two kinds, and the one, prestressed reinforced concrete case beam, the one, steel case beam, wherein, prestressed reinforced concrete case beam is site operation, except having longitudinal prestressing, some also arranges transverse prestress; Steel case beam is generally after processing in factory, to be transported to on-the-spot installation again, has full steel structure, also has part to add the reinforced concrete layer of mating formation.
Summary of the invention
The object of the present invention is to provide a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building, this construction technology can shorten construction period, reduces construction cost, reduces the probability that occurs security incident, has improved integral construction quality.
The present invention is achieved through the following technical solutions:
A construction of cast-in-situ box-beam technique that is applied to science of bridge building, comprises step successively: the installation → pre-pressing bracket → precompressed of bracket basis → support installation → end template unloads → adjusts the reinforcing bar of bed die absolute altitude → base plate and web and installed under prestressing → side template and inner formword and installs → build the reinforcing bar of base plate and web concrete → dismounting inner formword → top board and installed under prestressing → build top plate concrete → health 7 days → stretch-draw → mud jacking → support dismounting → end-blocking.
Further, described bracket basis adopts two kinds of forms: the first is that C30 reinforced concrete expands basis, key dimension is 2m × 7m, substrate is rock and adopts φ 28 Bar Anchorages, the long 2m of dowel, spacing 1m is 3 diameter 1.2m digging hole pile foundations of quincuncial arrangement, and hole pile foundation requires base bearing capacity to be at least 600KPa; The second is to expand basis, after to basis compacting, adopt light-duty cone penetrometer to carry out just trial and error test, adopt C30 concreting to build after reaching requirement, concrete foundation is pushed up pre-buried 2cm steel plate and bolt, gutter is set near bracket basis, avoids ponding to cause immerge.
Further, described support is installed: first in the time of vertical pier body formwork by bracket be connected shaped steel and put into template, and be an entirety by bracket with being connected shaped steel connection by rod member; After removing pier body formwork, pier body formwork is hung in pier side and built-in fitting and is linked together, connect horizontal leverage simultaneously, then transverse distribution beam and sand cylinder are installed.
Further, described support is removed: top plate concrete is made earth anchor at pre-buried φ 28 reinforcing bars of back before building, and 28 tons of hoist engines are set, at the reserved φ 100mm hole in wing plate position corresponding to steel pipe column; First the normal sand in 14 sandboxes is emitted simultaneously, bed die is removed with tower crane, then utilize chain block that 2 groups of Bailey beams are moved to wing plate position, 2 groups of Bailey beams are transferred to ground with hoist engine, utilize truck crane to dismantle on ground, utilize accordingly hoist engine or tower crane that crossbeam, bracket, steel pipe column have been dismantled.
Further, when described end template, side template and inner formword are installed: adjust end template absolute altitude according to precompressed data, adopt steel plate pad; Before template is installed, check its physical dimension, flatness, remove in time the foreign material in template, after precompressed unloading, want even brushing releasing agent; When template is installed, by span centre symmetrical installation to two ends, two side templates are installed simultaneously and are ensured to stablize; Template machines rear elder generation in the examination spelling of template field; Template install before by surveying party unwrapping wire, ensure smoothly linear, seam is tight, corner angle are clearly demarcated; Pull bar is firm, ensures when concrete construction not run mould, the mould that do not rise, spillage not; In both sides, beam-ends arranges spilled water hole, and concrete is built when foreign material in mould are cleaned and flowed out by spilled water hole; Template is installed front to template brushing releasing agent.
Further, described end template, side template and inner formword are removed: template unloads to two ends from span centre, laterally simultaneously, unload at longitudinal symmetrical equilibrium; Inner formword is removed reach 2.5MPa after concreting for the first time completes after, side template is removed reach 2.5MPa after concreting for the second time completes after, end template and support are removed after structure is set up prestressing force, utilize tower crane when form removable, and ensure that beam body corner angle are complete; Top template adopts hoist engine to transfer to the mobile trolley used of base plate place and above then draws to beam-ends with hoist engine, adopts tower crane to remove.
Further, described reinforcing bar and installed under prestressing order: build → top board of the concrete bottom layer of the reinforcing steel → top board transverse prestress → top board top layer of base plate bottom layer of the reinforcing steel → base plate transverse prestress → base plate top layer reinforcing bar → web reinforcement → longitudinal prestressing → vertical prestressing → for the first time reinforcing bar → build for the second time by concrete.
Further, described end template is assembled by 3.5m and 1.75m sizing punching block, between plate seam, smears putty, and 6mm steel plate is made panel, and 10cm channel-section steel is made perpendicular muscle, spacing 40cm, and 2 [ 18cm channel-section steel is made back cord, spacing 80cm, side template and inner formword all adopt 6mm steel plate to make panel, [ 10cm channel-section steel is made horizontal bar, back cord adopts [ 10cm channel-section steel assembling truss space 1.5m, by 3m, 2.5m sizing punching block is assemblied to form, inner formword pad adopts the high 50cmC50 precast concrete block of diameter 10cm, between inner formword, [ 10cm channel-section steel carries out stull in employing, diagonal brace, inside and outside intermode adopts three road φ 20mm round steel pull bars to reinforce, in inner side tie rod end, the long φ 25mmPVC pipe of 15cm is installed, when after form removable, by end pull bar excision 15cm, and adopt microdilatancy waterproof mortar shutoff tie rod hole and touch smooth guarantee and concrete surface solid colour.
Further, described hole path pressure grouting adopts vacuum aid grouting technology, and mud jacking mouth and steam vent are according to the setting of construction actual needs, after adopting compressed air removal of contamination before mud jacking, carry out again mud jacking, after tension of prestressed tendon anchoring, duct is mud jacking as early as possible, and completes in 48 hours.
The present invention compared with prior art, the beneficial effect having is: the present invention passes through construction procedure and the execution conditions in Optimizing construction process, thereby can shorten construction period, reduces construction cost, reduce the probability that occurs security incident, improved integral construction quality.
Detailed description of the invention
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment:
The invention discloses a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building, comprise successively step: the installation → pre-pressing bracket → precompressed of bracket basis → support installation → end template unloads → adjusts the reinforcing bar of bed die absolute altitude → base plate and web and installed under prestressing → side template and inner formword and installs → build the reinforcing bar of base plate and web concrete → dismounting inner formword → top board and installed under prestressing → build top plate concrete → health 7 days → stretch-draw → mud jacking → support dismounting → end-blocking.
Now, across the construction of freely-supported prestress box beam the present invention is further described for key water control project first stage of the project general main canal aqueduct C2 mark 50m in Guizhou Province.
First, according to geological condition, determine that bracket basis adopts two kinds of forms, the first is that C30 reinforced concrete expands basis, key dimension is 2m × 7m, and to require substrate be rock and adopt φ 28 Bar Anchorages, the long 2m of dowel, spacing 1m is 3 diameter 1.2m digging hole pile foundations of quincuncial arrangement, and hole pile foundation requires base bearing capacity to be not less than 600KPa. The second is to expand basis, for soil property basis, requires to adopt light-duty cone penetrometer to carry out just trial and error test after to basis compacting, adopts C30 concreting to build after reaching requirement, and concrete foundation is pushed up pre-buried 2cm steel plate and bolt. Gutter is set near bracket basis, avoids ponding to cause immerge. Support adopts three across unequal span Bailey beam structure, is 18m+7.41m+18m across spacing. Longeron laterally adopts 15 Bailey beams horizontally disposed, and spacing is the wide 7.2m of 0.9m+12 × 0.45m+0.9m(), between beam, laterally adopt 45cm, two kinds of bracing frames of 90cm to connect, bracing frame is established 6 roads altogether; Longitudinally Bailey beam is established 15, and long 45m, with groove pier joint specialized designs rod member, for preventing longeron slippage, with the groove pier joint pad lumps of wood. Transverse distribution beam adopts 4 long I32b I-steel of 9m, adopts steel to sew steel and connect between I-steel. Distribution beam is divided into the high steel sand cylinder of 25cm, and sand cylinder adopts δ 20 steel plates, φ 350mm(wall thickness 1cm) steel pipe, φ 310mm(wall thickness 1cm) steel pipe manufacturing, in upper sand cylinder, build C30 concrete, quicksand hole is established in lower sand cylinder weldering, and in-built normal sand is used for adjusting height and unloads. After sand cylinder installs, adopt double-layer plastic cloth to be wrapped up airtight, make moist with sand control cylinder internal standard sand, while unloading, normal sand cannot flow out automatically. [ on 40b channel-section steel shelf bracket, [ 40b, [ 28b channel-section steel is welded bracket horizon bar, and [ 40b channel-section steel is welded diagonal brace by 2 by 2 at 4 Pin 2 to distribute beam seat across end. Horizon bar is connected with the upper anchoring part pin that is embedded in pier shaft by bearing pin. Anchoring part adopts 20mm steel plate to process, plate size 1100*400*20mm, and two of anchoring parts, steel plate reserve anchor hole, adopts 20mm round steel pass anchor hole and be connected together in pier shaft steel bar welding, is embedded in pier shaft concrete in the time building pier shaft concrete. Diagonal brace one end adopts φ 80mm steel pin to be connected with the seat pin that casts anchor that is embedded in pier shaft, one end and horizon bar pin joint. For ensureing the monolithic stability of bracket, at bracket diagonal brace, horizontal-associate is set 4 Pin brackets are connected, horizontal-associate adopts 2 [ 32b, 2[28b channel-section steel and steel plate butt welding making. Span centre adopts double 6 Φ 820(wall thickness 10mm) steel pipe do buttress, arrange to layout 2 along bridge, 3 of lateral arrangement, 6 steel pipe columns form lattice by bridging, strengthen stability, steel pipe lower end supporting pile basis or to expand basis upper, between steel pipe and basis, all adopt flange to be connected between upper and lower steel pipe, ring flange adopts 16 φ 30mm(70mm long) high-strength bolt connection. Steel tube standard saves high 6m, adjusts high 4m, 3m, 2m, 1.5m, the 1m of being respectively of joint, and steel pipe buttress height deducts case beam base plate thickness, bed die height, Bailey beam height, distribution beam height, sand cylinder height and ground elevation by flowing water absolute altitude and considers definite. Steel pipe transverse connects and adopts 2 that [ butt welding of 28b channel-section steel, with φ 50mm steel pin bolt, diagonal brace adopts that [ 12.6 channel-section steels form bridgings, and connect with φ 30mm high-strength bolt, and spacing is one of 6m. For ensureing resistance to overturning and the anti-overturning of support, establish 4 gravity type anchor ingots in support both sides, connect and make guy with steel pipe column top with 4 road φ 26mm steel wire ropes.
Then carry out support installation: first in the time of vertical pier body formwork by bracket be connected shaped steel and imbed template, and to use the rod member identical with design size be an entirety by its connection; After dismounting pier body formwork, hung in pier side and built-in fitting and be linked together, connected horizontal leverage simultaneously, then transverse distribution beam and sand cylinder are installed. Steel pipe adopts tower crane segmental hoisting, and flange connects, and after every joint lifting puts in place, is connected firmly immediately with bolt, adjusts the vertical degree of steel pipe, and vertically degree must be less than 0.1%, and deviation is not more than 5mm. When installation, adopt plumb aligner to carry out monitoring measurement. Erection sequence is first to install successively across 6 interior steel pipes one, reaches behind first horizontal crossbar position, and horizontal bars and brace pin joint in length and breadth, merogenesis is reinforced. And then carry out the installation of next stage, and set up if desired interim cable wind rope, guarantee that steel pipe is stable. When erection of steel pipe column, forbid to apply in advance pulling force, in the time connecting diagonal brace or cross bar, if the discontented sufficient actual requirement of rod member length forbids to adopt the equipment such as bottle gouard moved by hands to carry out stretch-draw to rod member, now need rod member again processing and fabricating to guarantee to meet construction requirement. First Bailey truss is assembled by span burst on ground, is lifted on crossbeam, first marks the position of every longeron on crossbeam, truss is accurately lifted and is put in place, with the laterally connection of bracing frame do. The K Nodes contacting with pier stud and steel pipe column in Bailey beam adds 2, and [126 channel-section steels, as vertical supporting, often need 120 across 50m beam altogether. When installation, adopt horizon rule, spirit level to control sandbox height, sandbox will be exerted pressure before laying simultaneously, and the Bailey beam after installing is kept in one plane.
Then carry out end template installation, after installation, carry out pre-pressing bracket, pre-pressing bracket is the important step that support is checked and accepted, and it is that the work progress of simulating superstructure is tested to supporting, and is the necessary condition whether whether checking supported design is reasonable and can be delivered for use. Support is set up complete, in order to eliminate between support and the inelastic deformation of ground, and measures the strain value of support, and the line style of guard box beam and absolute altitude, carry out pre-pressing bracket according to designing requirement. 12 all carry out ballast test across simply supported beam support. According to designing requirement, prefabricating load is not less than 1.1 times of case beam deadweight, is often 435.8m across case beam concrete3, unit weight is got 26KN/m3, heap loading capacity is 1246 tons. Precompressed adopts 1 ton of special sand pocket to carry out piling prepressing, construction period, should carry out preparation and sluicing measure that rainy day sand pocket covers. Precompressed divides 40%, 80%, 110% 3 grade of precompressed, and its load weight is respectively 498.6 tons, 997 tons, 1246 tons, needs 1246 bags of sand, every bag of about 0.64m of area2, 360 tons of every layer of preloadings, four layers of preloadings can meet the demands completely, highly about 2.5m. Case beam cross section to web at the bottom of, 3, base plate center observes, longitudinally at distribution beam place and support single span span centre establish observation station and observe, before precompressed, bed die absolute altitude is observed once, first, second and third grade of loading observed for latter 2 hours, observes to till settlement stability; Pile foundation or expansion basis are carried out to settlement observation, totally six points; By again bed die absolute altitude being observed once after prefabricating load unloading, from above observational data, calculate the strain of support and the settling amount of ground.
Before loading, first measure each measuring point elevation of top surface H1 value and basic elevation J1 value with spirit level, while loading 40%, measure each measuring point elevation of top surface H2 value, while loading 80%, measure each measuring point elevation of top surface H3 value, while loading 110%, measure each measuring point elevation of top surface H4 value and basic elevation J2 value, after unloading, measure each measuring point elevation of top surface H5 value, carry out data to arrange analysis according to Measurement results, determine the camber of case beam, adjust bed die absolute altitude. Before precompressed, to check that support sets up situation, guarantee that the material of all uses all will meet the requirements, all solder joints, connect and want firmly, check one by one. When precompressed, want the symmetrical sand pocket of placing, in case bias voltage is unbalance. In loading and uninstall process, to prevent stress raisers, cause template to produce inhomogeneous deformation.
Then, carry out reinforcing bar and the installed under prestressing of base plate and web, side template and inner formword are installed, and build base plate and web concrete after installation, then remove inner formword, carry out reinforcing bar and the installed under prestressing of top board, then build after top plate concrete, health 7 days, and carry out stretch-draw and mud jacking, last striking, end-blocking, whole construction technology finishes.
Support in said process and the dismounting of all templates are propped up and are first torn open, first prop up the principle order of tearing open afterwards and carry out after should following. Top plate concrete is made earth anchor at pre-buried φ 28 reinforcing bars of back before building, and 28 tons of hoist engines are set, at the reserved φ 100mm hole in wing plate position corresponding to steel pipe column. First the normal sand in 14 sandboxes is released simultaneously, with tower crane, bed die is removed, then utilize chain block that 2 groups of Bailey beams are moved to wing plate position, with hoist engine, 2 groups of Bailey beams are transferred to ground, utilize truck crane to dismantle on ground. Utilize accordingly hoist engine or tower crane that crossbeam, bracket, steel pipe column have been dismantled.
When above-mentioned end template, side template and inner formword are installed, adjust bed die absolute altitude according to precompressed data, adopt steel plate pad; Before template is installed, check its physical dimension, flatness, remove in time the foreign material in template, after precompressed unloading, want even brushing releasing agent; When template is installed, by span centre symmetrical installation to two ends, two side templates are installed simultaneously and are ensured to stablize; Template machines rear elder generation in the examination spelling of template field; Template install before by surveying party unwrapping wire, ensure smoothly linear, seam is tight, corner angle are clearly demarcated; Pull bar is firm, ensures when concrete construction not run mould, the mould that do not rise, spillage not; In both sides, beam-ends arranges spilled water hole, and concrete is built when foreign material in mould are cleaned and flowed out by spilled water hole; Template is installed front to template brushing releasing agent. Before concrete is built for the first time, in top board chamfering position, reserved internal diameter 5cmPVC pipe is as internal mold top plate tie rod hole. Concrete is built rear dismounting web internal mold for the first time, and installation is fixed top board internal mold with φ 20mm round steel pull bar.
Above-mentioned end template, side template and inner formword are removed: template unloads to two ends from span centre, laterally simultaneously, unload at longitudinal symmetrical equilibrium; Inner formword is removed reach 2.5MPa after concreting for the first time completes after, side template is removed reach 2.5MPa after concreting for the second time completes after, end template and support are removed after structure is set up prestressing force, utilize tower crane when form removable, and ensure that beam body corner angle are complete; Top template adopts hoist engine to transfer to the mobile trolley used of base plate place and above then draws to beam-ends with hoist engine, adopts tower crane to remove. Unsuitable form removal when temperature sharply changes, removes end mould, inner membrance, the side form covering curing of later sprinkling water.
Above-mentioned reinforcing bar and installed under prestressing order: build → top board of the concrete bottom layer of the reinforcing steel → top board transverse prestress → top board top layer of base plate bottom layer of the reinforcing steel → base plate transverse prestress → base plate top layer reinforcing bar → web reinforcement → longitudinal prestressing → vertical prestressing → for the first time reinforcing bar → build for the second time by concrete. Reinforcing bar adopts HRB400, is divided into 10mm, 12mm, 16mm, tetra-kinds of specifications of 20mm. Splice adopts welding, and joint location staggers mutually, and the quantity of arbitrary section splice must be less than 50% of reinforcing bar radical. The length of double welded joint is not less than 5d, and single fillet welded length is not less than 10d. Beam body reinforcing bar Minimal Protective layer is 35mm, adopts plastic cushion to guarantee headroom. When reinforcing bar welding, lower bellows need be covered, in order to avoid welding slag destroys its scaling loss.
Above-mentioned concrete adopts automatic gauge mixing, and concrete tank car is transported to job site, and pumping is put in storage. Concrete is built front raw material reserve status and the inspection situation of first checking, the water content of sand material is detected, and determines construction match ratio, issues charger sheet to blending station by laboratory. Mix will stir, and solid colour must not have segregation and excreting water phenomenon, and the slump to concrete, air content, out-of-machine temperature, placement temperature detect, and makes on request the raw test specimen of real curing, stretch-draw test specimen. Concreting principle: first build base plate and build again web; Left and right web symmetry is built; Concrete is built to two ends in the middle of beam body, adopts 2 concrete pumps while symmetries to carry out. Concrete delamination thickness 30 ㎝, the front and back of upper strata and lower floor are built distance and are decided to be 10m. Concrete is built with building for the second time the length of time and should do not exceeded 7 days for the first time, sets up reinforced mesh at connecting portion simultaneously. Carrying out needing the concrete to building for the first time to carry out dabbing processing before concreting for the second time, and adopt high pressure geomantic omen to rinse well, ensure in the face of storehouse without any foreign material. In box beam concrete casting process, must carry out continuously, must not interrupt, concrete the building in upper strata must complete before the initial set of lower-layer concrete. Continuous concreting, one-shot forming. Strengthen the concrete casting building technology at bearing, anchor plate, bellows below place, guarantee vibration compacting. In concrete casting process, arrange special messenger to check support and template deformation situation. Concrete adopts poker vibrator to vibrate, layout evenly, when concrete vibrating, forbid vibrating spear to touch bellows, in order to avoid there is displacement, hole seam spillage in bellows, affect stretch-draw, concrete tamping degree with its blibbing of field observation stopped discharging, concrete no longer sinks and occurs that on surface cement mortar is as the criterion, and after everywhere has shaken, should slowly propose vibrating spear. Moving interval should not exceed 1.5 times of vibrating spear operating radius, and keeps the distance of 5~10cm with side form, inserts lower-layer concrete 5~10cm while vibrating. The personnel of building are divided into Liang Ge teams and groups, and each teams and groups establish 1 commander, 3 works of vibrating, and four general works are responsible for dismantling pump line. Subregion vibrates, and carries out the system of listing, clearly defining responsibilities. After concreting, adopt secondary to receive sizing process, wipe one's face for the first time routinely and receive after slurry, then wipe one's face for the second time and receive slurry, the time of wiping one's face is selected in to build and carries out for rear 6-8 hour for the second time. After concrete final set, start to cover geotextiles watering maintenance, prevent that moisture evaporation is too fast, special messenger is responsible for, and the frequency of watering must ensure that concrete surface is moistening. The temperature difference between water temperature and the concrete surface of maintenance should be controlled in 15 DEG C, prevents due to excessive temperature differentials, causes concrete to crack. After case beam side is removed, owing to cannot wrapping up covering, concrete wet curing outside case beam.
Above-mentioned concrete proportioning design and control with raw material are:
A. design by impervious concrete when mix Design, adopt normal silicate P.O52.5 class g cement, aluminic acid acid calcium content is 6-8%.
B. maximum size of coarse aggregate is 25mm, adopts washing measure, strictly controls coarse aggregate clay content, clod content is less than 0.2%; Fine aggregate adopts the rubble of washing to process, and clay content, clod content all can be effectively controlled; Fine aggregate modulus of fineness is controlled at 2.4-2.8, and content of stone powder is controlled in 7%.
C. additive adopts Shanxi Huang to rise the efficient retardation water reducing agent of high-performance poly carboxylic acid; Cement consumption is 425Kg/m3, be greater than the 320Kg/m of code requirement3; Sand coarse aggregate ratio is 37.5%, and the ratio of mud is 0.32; Examination timing adopts the cooperation of ratio of mud maximum to liken impermeability test to.
D. mix 50Kg flyash in order to reduce cement consumption, thereby reduce the total water heat-transmission of cement, improve concrete workability, thereby avoid concrete crack.
Above-mentioned concrete construction control is:
a.The strict thickness of protection tier of controlling, clean protective layer thickness is greater than 19mm, takes C55 high-grade concrete cushion block.
b.During hot weather construction, temperature is higher, takes the aggregate cooling measure that waters, and reduces concrete and goes out machine and molding temperature, controls concrete molding temperature and is less than 32oC. To the cooling of washing by water of concrete transport vehicle vehicle body, site inspection outlet temperature. When concrete is built, strictly control concrete slump is 160-200mm. Pump line in use can radiation-absorbing warm, and pipeline and concrete material friction also can produce heat, wrap up gunnysack on conveyance conduit, and the cooling of throwing cold water on pipeline, irregularly water in the above, ensure that building insulation material in concrete process be moisture state.
c.Ensure the continuity that concrete is built, do not occur construction joint or cold seam. Construction machinery not only will be made adequate preparation, and repairing time will consider to break down time, mixing plant two concrete tank cars for subsequent use, and an on-the-spot delivery pump for subsequent use, wants a 300KW generator for subsequent use in addition, and blending station configures a set of 750 mixing plants.
Building before concrete and construction machinery should be transported to scene. Mixing plant is got enough cement, sand, stone ready and is ensured that water and electricity supply, machinery allocation must accomplish continuous construction, workmen's configuration operating personnel that works in three shifts.
d.According to concrete conveying capacity, bottom slab concreting area, the concrete amount of building, carry out subregion, layering to building concrete, make concrete with same gradient thin concrete lift, advance in proper order, once arrive top, each lift height is built by 300mm layering substep, and will ensure that concrete covers the time of having built concrete and must not exceed the concrete presetting period.
e.The actual conditions of a gradient of self-assembling formation during according to concrete pumping, each build band before, during and after arrange that three roads vibrate. First is arranged in pouring out concrete point, mainly solves the concrete tamping in top, and because baseplate reinforcing bar spacing is closeer, second is arranged in concrete toe place, guarantees that bottom is concrete closely knit, and San road ensures the gradient and the density of concrete at the middle part of the gradient. Along with pushing ahead of concreting work, vibrating spear is corresponding catching up with also, to guarantee the concrete quality of whole height. After chamfer length increases, vibrating head is also wanted corresponding increase number.
Construction manager is supervised the conscientious compacted concrete of workman at the scene, improves concrete packing, reduces the space between concrete aggregate.
f.The concrete indices of mixing is strictly monitored in job site, circulate a notice of at any time, and the concrete quality problem in time scene being occurred is processed to the director of site operation. Testing crew is spot-check the slump of concrete at any time, the workability of range estimation concrete, as find concrete have segregation or just coagulation phenomena the concrete appearance of clearing up and discharging.
g.After concreting, adopt secondary to receive sizing process, wipe one's face for the first time routinely and receive after slurry, then wipe one's face for the second time and receive slurry, the time of wiping one's face is selected in to build and carries out for rear 6-8 hour for the second time.
h.After concrete final set, start to cover geotextiles watering maintenance, prevent that moisture evaporation is too fast, special messenger is responsible for, and the frequency of watering must ensure that concrete surface is moistening. The time of concrete watering maintenance is 14 days. The temperature difference between water temperature and the concrete surface of maintenance should be controlled in 15 DEG C, prevents due to excessive temperature differentials, causes concrete to crack. After case beam side is removed, owing to cannot wrapping up covering, concrete wet curing outside case beam. Concrete pours in rear cabinet and covers in time gunnysack or straw screen or mat (bag) often watering, in top board stretch-draw hand-hole place and case, establishes powerful fan, and accelerating chamber inner air flow, reduces air themperature in case, utilizes the cooling measures such as vertical finish rolling corrugated steel pipe water flowing.
i.The cement mortar of the concrete surface that reply is built for the first time before concreting for the second time and soft layer cut, and adopt high pressure geomantic omen to be incorporated into row and rinse, the foreign material of storehouse face are cleaned out, and abundant moistening storehouse face but must not ponding; Dabbing should make to expose fresh concrete area and be not less than 75%; When artificial chiseling, concrete strength should reach 2.5MPa, and when air operated machine dabbing, concrete strength should reach 10Mpa. Set up steel bar welding net and mesh resin fiber at connecting portion simultaneously.
j.According to flat perpendicular curved geometric element calculate bellows from center vertical lateral coordinates of every 50cm, adopt one U-shaped φ 14 reinforcing bar of 80cm to position, the every 50cm of curved section is location together, require pipeline location accurate, firm, pipeline is straight, and the radius of curvature of arbitrary paragraph must not be less than 95% of design load. Pipeline installation deviation: pipeline coordinate beam length direction is less than 30mm, and deck-molding direction is less than 10mm; Spacing between pipes is less than 10mm with row, and levels is less than 10mm. Anchor plate will be installed firmly accurately, and anchor plate, pipeline are must centering straight, remain on same axis, guarantee vertical with corrugated tube end. Concrete is built front inspection anchor plate and pipeline, and the position of anchor plate should be accurate, unimpeded anhydrous and other foreign material in duct.
Above-mentioned hole path pressure grouting adopts vacuum aid grouting technology. Adopt Special grouting material to carry out mud jacking, burnt family aqueduct needs 37m3, and a stream aqueduct needs 74m3. Mud jacking mouth and steam vent can be according to the actual needs settings of constructing, can mud jacking after the front application of compressed air removal of contamination of mud jacking. After tension of prestressed tendon anchoring, duct is mud jacking as early as possible, and should in 48 hours, complete.
Preparation before hole path pressure grouting:
The cutting of use emery wheel, the remaining length after presstressed reinforcing steel cuts off must not be less than 30mm. Clog with cement mortar in the presstressed reinforcing steel gap of ground tackle outside, in order to avoid grout and lose grouting pressure. Reserved steam vent when sealing off and covering anchorage. Duct is rinsed with press water before mud jacking, with foreign material such as granulated slags in evacuation aperture, ensures that duct is unimpeded. After flushing, blow away hole internal water accumulation with air compressor machine, compressed air will be without oil content. But keep duct wetting, make the combination of cement mortar and hole wall good.
Pipeline pneumatic mortar requires closely knit, and hole path pressure grouting adopts neat slurry, and mud jacking match ratio will, carefully than choosing, adopt optimum mix proportion, must not mix all kinds of villaumites, and within 28 days, requirement of strength reaches 50MPa. Cement adopts the low alkali Portland cement of P.O52.5, and additive adopts Shanxi Huang to rise high-performance high-efficiency water-reducing agent of poly-carboxylic acid, and water-cement ratio adopts 0.26-0.28, and maximum is no more than 3%. Mixing and stirring rear 3h bleeding rate should be controlled at bleeding after 2%, 24h and should all be absorbed by slurry. Denseness requires to be controlled at 14~22s. In cement mortar, (by testing) mixes suitable swelling agent. The free wxpansion that cement mortar mixes after swelling agent is greater than 3%.
The mud that discharges water again that first discharges water, the mixing time is no less than lmin, after mortar sieves, deposits in slurry storing tank. Now in bucket, mortar is still wanted stirring at low speed, and often keeps enough quantity to complete with the mud jacking energy one-time continuous that ensures every pipeline. Cement mortar automodulation must not exceed 4Omin to the interval time of pressing people's pipeline.
In summary: construction method disclosed by the invention is passed through to optimize construction procedure and the execution conditions in construction of cast-in-situ box-beam process, thereby can shorten construction period, reduces construction cost, reduces the probability that occurs security incident, has improved integral construction quality.
The above, be only preferred embodiment of the present invention, not the present invention done to any pro forma restriction, and any simple modification, equivalent variations that every foundation technical spirit of the present invention is done above embodiment, within all falling into protection scope of the present invention.

Claims (8)

1. one kind is applied to the construction of cast-in-situ box-beam technique of science of bridge building, it is characterized in that, comprise successively step: the installation → pre-pressing bracket → precompressed of bracket basis → support installation → end template unloads → adjusts the reinforcing bar of bed die absolute altitude → base plate and web and installed under prestressing → side template and inner formword and installs → build the reinforcing bar of base plate and web concrete → dismounting inner formword → top board and installed under prestressing → build top plate concrete → health 7 days → stretch-draw → hole path pressure grouting → support dismounting → end-blocking; Described bracket basis adopts two kinds of forms: the first is that C30 reinforced concrete expands basis, key dimension is 2m × 7m, substrate is rock and adopts φ 28 Bar Anchorages, the long 2m of dowel, spacing 1m is 3 diameter 1.2m digging hole pile foundations of quincuncial arrangement, and hole pile foundation requires base bearing capacity to be at least 600KPa; The second is to expand basis, after to basis compacting, adopt light-duty cone penetrometer to carry out just trial and error test, adopt C30 concreting to build after reaching requirement, concrete foundation is pushed up pre-buried 2cm steel plate and bolt, gutter is set near bracket basis, avoids ponding to cause immerge.
2. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, it is characterized in that, described support is installed: first in the time of vertical pier body formwork by bracket be connected shaped steel and put into template, and be an entirety by bracket with being connected shaped steel connection by rod member; After removing pier body formwork, pier body formwork is hung in pier side and built-in fitting and is linked together, connect horizontal leverage simultaneously, then transverse distribution beam and sand cylinder are installed.
3. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, it is characterized in that, described support is removed: top plate concrete is made earth anchor at pre-buried φ 28 reinforcing bars of back before building, and 28 tons of hoist engines are set, at the reserved φ 100mm hole in wing plate position corresponding to steel pipe column; First the normal sand in 14 sandboxes is emitted simultaneously, bed die is removed with tower crane, then utilize chain block that 2 groups of Bailey beams are moved to wing plate position, 2 groups of Bailey beams are transferred to ground with hoist engine, utilize truck crane to dismantle on ground, utilize accordingly hoist engine or tower crane that crossbeam, bracket, steel pipe column have been dismantled.
4. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, is characterized in that, described end template, side template and inner formword are installed: adjust end template absolute altitude according to precompressed data, adopt steel plate pad; Before template is installed, check its physical dimension, flatness, remove in time the foreign material in template, even brushing releasing agent after precompressed unloading; When template is installed, by span centre symmetrical installation to two ends, two side templates are installed simultaneously and are ensured to stablize; Template machines rear elder generation in the examination spelling of template field; Template install before by surveying party unwrapping wire, ensure smoothly linear, seam is tight, corner angle are clearly demarcated; Pull bar is firm, ensures when concrete construction not run mould, the mould that do not rise, spillage not; In both sides, beam-ends arranges spilled water hole, and concrete is built when foreign material in mould are cleaned and flowed out by spilled water hole; Template is installed front to template brushing releasing agent.
5. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, is characterized in that, described end template, side template and inner formword are removed: template unloads to two ends from span centre, laterally simultaneously, unload at longitudinal symmetrical equilibrium; Inner formword is removed reach 2.5MPa after concreting for the first time completes after, side template is removed reach 2.5MPa after concreting for the second time completes after, end template and support are removed after structure is set up prestressing force, utilize tower crane when form removable, and ensure that beam body corner angle are complete; Top template adopts hoist engine to transfer to the mobile trolley used of base plate place and above then draws to beam-ends with hoist engine, adopts tower crane to remove.
6. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, it is characterized in that described reinforcing bar and installed under prestressing order: build → top board of the concrete bottom layer of the reinforcing steel → top board transverse prestress → top board top layer of base plate bottom layer of the reinforcing steel → base plate transverse prestress → base plate top layer reinforcing bar → web reinforcement → longitudinal prestressing → vertical prestressing → for the first time reinforcing bar → build for the second time by concrete.
7. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, it is characterized in that, described end template is assembled by 3.5m and 1.75m sizing punching block, between plate seam, smear putty, 6mm steel plate is made panel, and [ 10cm channel-section steel is made perpendicular muscle, spacing 40cm, 2 [ 18cm channel-section steel is made back cord, spacing 80cm, side template and inner formword all adopt 6mm steel plate to make panel, [ 10cm channel-section steel is made horizontal bar, back cord adopts [ 10cm channel-section steel assembling truss space 1.5m, by 3m, 2.5m sizing punching block is assemblied to form, inner formword pad adopts the high 50cmC50 precast concrete block of diameter 10cm, between inner formword, [ 10cm channel-section steel carries out stull in employing, diagonal brace, inside and outside intermode adopts three road φ 20mm round steel pull bars to reinforce, in inner side tie rod end, the long φ 25mmPVC pipe of 15cm is installed, when after form removable, by end pull bar excision 15cm, and adopt microdilatancy waterproof mortar shutoff tie rod hole and touch smooth guarantee and concrete surface solid colour.
8. a kind of construction of cast-in-situ box-beam technique that is applied to science of bridge building according to claim 1, it is characterized in that, described hole path pressure grouting adopts vacuum aid grouting technology, mud jacking mouth and steam vent are according to the setting of construction actual needs, after adopting compressed air removal of contamination before mud jacking, carry out again mud jacking, after tension of prestressed tendon anchoring, duct is mud jacking as early as possible, and completes in 48 hours.
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CN106592437B (en) * 2016-12-16 2018-02-16 曹晓滨 A kind of cast-in-situ construction method of cast-in-place concrete bridge
CN107460827A (en) * 2017-08-09 2017-12-12 中国十七冶集团有限公司 A kind of method of cast-in-situ box girder form bracing system precompressed
CN109016127B (en) * 2018-07-27 2020-07-24 中国十七冶集团有限公司 Bridge arch box prefabrication production and transverse connection method thereof
CN110258340A (en) * 2019-06-11 2019-09-20 中铁一局集团有限公司 A kind of segmented efficient construction method of groove profile continuous beam
CN110847044A (en) * 2019-11-15 2020-02-28 中交第二航务工程局有限公司 Semi-prefabricated assembled bent cap construction method
CN111501576A (en) * 2020-05-18 2020-08-07 湖南交通国际经济工程合作有限公司 Standardized prefabrication construction method for bridge beam plate and standardized prefabricated beam plate

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