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1、現澆預應力連續箱梁的施工工藝及質量控制摘要:對預應力橋梁工程的施工工藝進行進一步的探討和研究,同時對現澆連續箱梁需要注意的施工細節提出建議。關鍵詞:現澆箱梁;施工;工藝1工程概況(阜朝高速公路K443+780平安地公鐵立交橋為例)K443+780平安地公鐵立交橋,橋長100m,分左右雙幅橋,單幅寬為12.50m,跨徑為30+40+30m,其中中跨為40m,分別上跨錦承鐵路及地方公路,上部結構采用預應力混凝土現澆連續箱梁,縱向采用四層預應力鋼絞線,梁高由1.50m過渡到2.5m;橫向設置兩層預應力鋼絞線,底層間距90cm,上層間距60cm;豎向設置精軋螺紋預應力鋼筋,間距60cm。下部結構采用樁2、基礎、承臺,方柱式墩、肋板臺。2現澆箱梁施工工藝及質量控制2.1地基處理第1、3孔在橋跨與橋寬范圍內,將場地平整,采用18t以上振動壓路機碾壓45遍,回填碎石50100cm使地面高程距箱梁底高程距離約6.0m。壓實度不小于90%,按橫向間距0.9m,布置20cm20cm的水平枕木,使壓力擴散,確保支架在施工中不發生變形與失穩。地基回填后,開挖一定數量的排水溝,防止雨水對支架底部的浸泡。2.2支架搭設及支座安裝(1)支架布置:第1、3孔支架采用標準碗扣式腳手架,該支架輕巧,拼裝方便,為保證支架的強度及整體穩定性,支架采用四體品字形雙層結構排列,支架底部墊20cm15cm水平方與地面之間鋪一層石屑3、或小石子找平。支架之間用的鋼管將門架縱橫交叉聯結,內部及外側用鋼管作剪刀撐,并用鋼絲繩對稱斜拉,在箱梁肋板,橫隔板位置處支架加密1倍,懸臂板部分可適當減少一些。上托頂架鋪設方木,其支架高度可按地形及門式腳架調整搭設,利用上托調整預拱度。第2孔為跨鐵路橋孔,按照鐵路部門的要求確保鐵軌兩側的凈距不少于8.5m的要求,在鐵軌兩側做監時鋼支架,基礎挖深2.0m,回填1.0m石渣,再澆筑1.0m的鋼筋混凝土,并在每側各放三個鋼支架,上面縱向采用桁架片做縱梁,采用45b工字鋼做橫梁,間距0.9m。(2)支架驗算:鋼管腳手架的穩定性檢算強度驗算,根據建筑施工扣件式腳手架安全技術規范,模板支架主要檢算立桿穩定4、性。支架步距及縱距0.9m、橫距均按0.9m檢算。計算時主要考慮的荷載包括梁體鋼筋混凝土自重、模板自重、支架自重、施工人員及機具重量、混凝土灌注振搗等。經驗算采用穩定性滿足要求方可進行施工?？缭借F路上方的鋼支架縱、橫梁強度驗算,計算時主要考慮的因素是梁體鋼筋混凝土自重、模板自重、施工人員及機具重量、混凝土灌注振搗等,經驗算縱、橫梁強度滿足要求后方可進行施工。支架搭設完后,在墩柱及臺身上用經緯儀準確測放出支座中心點位置,并按照設計圖紙要求安裝支座。2.3支架預拱度設置預拱度計算公式:f=f1+f2,其中f1為支架彈性變形;f2為梁體撓度預拱度,最大值設在梁的跨中位置,并按拋物線形式進行分配,算得5、各點的預拱度值后,通過支架上的可調絲桿頂托或底座對底模進行調整。2.4模板的制作、安裝及支架的預壓支座安裝合格后,依據圖紙尺寸加工并安裝箱梁底模板,底模板鋼模板,側模板采用優質進口竹膠合板(1.2cm厚),表面光潔度、平整度、線條平順均能滿足美觀要求,其剛度強度能滿足要求。模板接縫處嵌填海綿條或采用膠帶封縫,并設置斜撐和壓腳,以防跑模和漏漿。模板安裝前,檢查其是否變形、污染。支架底模高程計入落地支架彈性、非彈性變形值,其他位置按拋物線設置預拱度,以確保箱梁的標高符合設計要求。預壓完成后,卸去砂包,把模板清洗干凈,并涂刷優質脫模劑。重新測量標高調整底板。支架靜預壓:在支架搭設完成以后,應對支架進6、行預壓,預壓荷載不小于梁體鋼筋混凝土重量的1.2倍,預壓采用砂(或土)袋預壓,其荷載分布與現澆箱梁重量分布情況一致,預壓期間在每跨設置五個斷面15個觀測點,預壓前先測量復核支點標高,砂袋用吊機吊放到支架上,試壓分三次水平加載,第一次試壓重40%,第二次為40%,第三次全部加完,然后觀測7d,卸載按三次進行,第一次按試重的20%,第二次為40%,第三次全部卸完,每個觀測點在每一次加載(卸載)完了及全部加載完(卸載完)均要觀測,全部加載完成后先每一天觀測一次,若連續7d觀測結果在5mm以內,則可以認為地基沉降基本穩定。2.5鋼筋、波紋管、鋼絞線安裝調整底板合格后、安扎鋼筋、安扎時分兩次,第一次安扎7、鋼筋為底肋板,在底板及肋板澆筑混凝土后安扎箱頂及懸臂預埋鋼筋,在澆筑箱頂板時,在頂板應力最小處(1/4跨)開11.5m天窗(每一箱1個)拆除箱內模板、支架后將天窗鋼筋焊接好,并采用與箱梁同標號混凝土澆筑平整。在安裝綁扎完底板鋼筋及橫隔板骨架后,安放縱、橫向、豎向波紋管、鋼絞線安裝完后,再綁扎肋板鋼筋。鋼絞線安裝程序:先按其長度,編號穿入波紋管,分布在肋部位置,再將波紋管及應力鋼束按坐標要素表準確定位,采用鋼筋“#”字架1.0m間距將鋼束固定,彎曲部位間距為0.5cm,重復檢查,穿鋼束時波紋管是否有破裂,波紋管接口處采用橡膠條或封口膠布包裹密封,外用鐵絲扎緊,當鋼筋與鋼束位置發生矛盾時,鋼筋讓位8、于鋼束,在箱梁波紋管頂峰處引出氣孔,(用小膠管引出),安裝好波紋管鋼束后,重新檢查其坐標位置是否符合要求,進行調整,后完善其他肋板及橫隔板鋼筋,待混凝土澆注后,及時將鋼絞線在橋兩頭利用卷揚機來回拉動,施工時特別注意防止波紋管漏漿及壓扁引起下一道工序的困難。安放縱、橫、豎向波紋管時一定要按照圖紙給定的坐標進行,不能隨意改動,發生預應力鋼筋與普通鋼筋有抵觸的地方要以預應力鋼筋為主,變動普通鋼筋的位置。2.6混凝土攪拌、運輸、澆筑及其養生(1)混凝土由2臺L1000強制式攪拌機攪拌,由攪拌站統一供給。配料由電子秤控制(已經過計量部門檢測標定),并嚴格按照中心試驗室提供的混凝土配合比攪拌,由4臺8m攪9、拌車運輸、采用泵送混凝土澆筑施工,配8臺插入式振動棒振搗。(2)箱梁混凝土分兩次澆筑(第一層為底板及肋板根部50cm高,第二層為肋板、頂板和懸臂板)。箱梁底板和肋板混凝土采用斜層法由低端向高端澆筑。并由低向高推進。混凝土初凝后,用鋼絲刷拉毛,使其表面粗糙而平整、清潔。以便于橋面鋪裝混凝土的結合質量。第一層混凝土澆筑時采用插入式振搗器振搗,并振搗密實。同時每個工作班制取試塊不少于5組。最后一層施工的混凝土,把二組試塊放在箱梁上同條件下養護,采用覆蓋養生。2.7預應力張拉(1)在混凝土強度達到設計強度100%后,且齡期達到14d后方可進行張拉。預應力鋼束張拉嚴格按照設計圖紙提供的張拉順序和張拉控制10、應力進行。張拉設備在使用前須進行檢查和校核。(2)本橋預應力箱梁采用后張法,預應力筋為低松弛預應力鋼鉸線,張拉工藝根據設計圖紙縱向預應力鋼絞線采用兩端同時張拉,橫向預應力鋼絞線采一端張拉,豎向預應力鋼筋采用在梁頂面張拉。(3)預應力張拉采用雙控,以張拉力進行控制,以伸長量進行校核,實際伸長量值與理論伸長值之差若超過規范要求應暫停張拉,查明原因并采取措施加以調整后,再繼續張拉。(4)張拉設備校核:張拉機具與錨具配套使用,在進場使用前進行檢查與校核,每臺千斤頂與壓力表、壓力盒、測力計及其他裝置,應具有1%的讀數精度。壓力表精度不應低于1.5級。千斤頂一般使用超過6個月或200次,以及在使用中出現不11、正?，F象時,應重新校準。(5)張拉筋制作:每根預應力鋼筋應標簽以編號及盤號或使用鋼材的號碼,鋼絞線不得扭折、絞旋,不得松散,且每根鋼絞線在構件每端要易于識別。鋼絞線下料長度應把兩端工作長度計算在內、張拉后鋼絞線的切割用高速手砂輪切割機,外露長度35mm。(6)縱、橫向鋼鉸線張拉操作程序為:0初應力(10%k)k測伸長度油缸回零、測回縮量(持荷2min)。2.8孔道壓漿(1)壓漿前,先吹入無油份的壓縮空氣清洗管道,再用含0.01kg/L生石灰或氫氧化鈣的清水沖洗管道,再以壓縮空氣吹干。(2)用水泥制漿攪拌機制備符合要求的水泥漿。首先將水加入拌和機內,再放入水泥,經充分拌和后摻入摻加劑(如果需要)12、,(壓漿前須經過濾,)拌和應至少2min,直至達到均勻的稠度為止。然后將壓漿泵輸出管與一根壓漿管的甲端相連接。(3)啟動活塞式壓漿泵由甲端進漿,從乙端排氣,直到乙端排氣孔流出符合規定稠度的濃漿后,關閉乙端閥門,并保持不小于0.5MPa的一個穩壓期,該穩壓期不少于2min,然后關閉甲端閥門。(4)間隔3045min,再從乙端壓漿,從甲端排氣,直到甲端排氣孔流出符合規定稠度的濃漿后,關閉甲端閥門,并保持不小于0.5MPa的一個穩壓期,該穩壓期不少于2min,關閉乙端閥門。(5)壓漿施工過程中填寫完備的壓漿記錄,包括每個管道的壓漿日期、水灰比及摻加料、壓漿壓力、障礙事故細節及需要補做的工作。(6)壓13、滿漿的管道應進行保護,使在一天內不受振動,管道內水泥漿注入后的48h內,結構混凝土溫度不得低于5,否則應采取保溫措施;當白天氣溫高于35時,壓漿宜在夜間進行。2.9封錨為了保護外露的錨具不致銹蝕而失效,當灌漿完畢后,將外露部分進行清洗,并將端面混凝土鑿毛,并綁扎鋼筋。錨后鋼筋網與預留鋼筋點焊一體,然后安裝模板,澆筑混凝土。壓漿封錨后,待壓漿強度達到80%后,拆卸支頂架。2.10支架、模板的拆除在壓漿強度達90%及封錨完成后拆除所有支架。拆除支架時從跨中開始對稱向兩頭均勻拆卸,以便使橋體重量對稱、均勻地由兩端支座平均承擔,同時預防箱梁因受力不均勻產生裂紋。拆除底模時防止損壞箱梁外觀質量。3結束語14、在施工過程中,應當根據圖紙要求、施工設備、現場施工條件、等各方面情況綜合考慮。認真、謹慎的做每一道施工工序,采取積極有效的措施,保證工程質量、節約成本、確保施工安全。Prestressed continuous box girder construction technology and quality control Abstract: The construction technology of prestressed bridge engineering for further exploration and study, recommendations Cast - need to p15、ay attention to construction details.Keywords: cast-in-place box girder; construction; craft a project overview (Fu toward the highway K443 +780 safely rail overpass as an example) K443 +780 safely rail overpass bridge length of 100 m, at about double the rate of bridge, a singlewidth of 50 m span i16、s 30 +40 to +30 m, which in the span of 40 m, respectively, on cross-Jin Cheng rail and local roads, the superstructure of prestressed concrete Cast - vertical with fourlayer of prestressing strand, high beam transition from 50 m to 5 m; horizontal set of two-tier PC strand, the bottom spacing of 9017、 cm, the upper layer spacing of 60 cm; vertical settings finishing thread prestressed reinforcement, spacing of 60 cm.Substructure pile foundation, pile cap, square column piers, ribs, Taiwan.2 Cast - Construction technology and quality control 2.1 foundation to deal with the 1st and 3rd holes cross18、 the bridge and the bridge width within the site preparation, more than 18 t vibratory roller RCC 4 to 5 times, backfill gravel 50 100cm so that the ground elevation from the elevation distance from the end of the box girder of about 6 0 m.The degree of compaction of not less than 90%, the horizonta19、l distance of 9 m, 20 cm 20 cm sleepers layout, so that the pressure diffusion, and to ensure that the stent does not occur in the construction of deformation and instability.Foundation backfill, excavation of a certain number of drains, to prevent the rain from soaking the bottom of the bracket.Ins20、tallation of of 2.2 Scaffording and bearing bracket arrangement (1): 1, 3 hole bracket standard of scaffold, the stent lightweight, convenient assembling, in order to ensure the strength and overall stability of the stent, the stent using the four-body and twin pairslayer structure arranged in the b21、ottom of the bracket pad between the shop in the 20 cm 15 cm horizontal with the ground layer of stone chips or gravel leveling.Steel pipe used in the bracket between the door frame vertical and horizontal cross-links, internal and lateral steel pipe scissors, and wire rope symmetrical cable-stayed 22、box girder ribs, diaphragm position bracket encryption times a cantilever plate part may be appropriate to reduce thesome.On the care the top frame laying of square wood, the frame height according to the terrain and the gantry stand adjustment, erection, on child care to adjust the pre-camber.2 hol23、es for the cross-rail bridge opening, in accordance with the requirements of the railway authorities to ensure that the rails on both sides of the spacing of not less than 8 5 m, the tracks on both sides of the steel bracket when the supervisor, basic deepened 2 0 m, backfilling a0 m gravel, and the24、n pouring 1 0 m reinforced concrete, and on each side and put three steel frame above vertical truss piece stringers, 45b beam do beam spacing of 9 m.(2) stent checking: the stability of steel scaffolding Calculation strength calculation, construction fastener Scaffolding Safety Technical Code, the 25、template bracket Calculation pole stability.Stent step away from the vertical distance. 9m horizontal distance at 0. 9m Calculation.The main consideration in the calculation loads include the weight of the beam reinforced concrete, templates weight, weight bracket, construction personnel and equipme26、nt weight, the pouring of concrete vibrators.Experience counted using the stability to meet the requirements before construction.Across the rail above the steel bracket longitudinal beam strength calculation, the main consideration in the calculation is the reinforced concrete of the beam weight, we27、ight template, construction personnel and equipment weight, the pouring of concrete vibrators, experience counted longitudinal beam intensity to meet the requirements beforeconstruction.Scaffording after theodolite accurately measured in the pier columns and Taiwan who release bearing center positio28、n, and in accordance with design drawings require the installation of the bearing.2.3 stent pre-camber settings pre-camber of the formula: f = f1 + f2, where f1 is the the bracket elastic deformation; pre-camber of f2 for the beam deflection, the maximum located at the cross in the position of the b29、eam, according to the parabolic form of allocated, regarded as the point of pre-camber value after adjustment by backwater or base of the adjustable screw on the bracket on the bottom die.Preloading bearings 2.4 template production, installation and bracket installation is qualified in accordance wi30、th sheet size processing and installation box girder end of template, the end of the template of steel formwork side of the template with high-quality imported bamboo plywood (2 cm thick), surface finish, flatness, and smooth lines can meet the aesthetic requirements, the stiffness strength to meet 31、the requirements.Template seams filling them with a sponge or the use of tape Sealing and bracing and the presser foot to prevent run-mode and leakage of plasma.The installation of the template, check whether the deformation of the pollution.Mode elevation end of the bracket included in the floor st32、and flexible, non-elastic deformation and other locations according to the parabolic set of pre-camber, to ensure the elevation of the box girder to meet the design requirements.Preloading is completed, to unload sand bags, clean template, and brushing quality release agent.Re-measured the elevation33、 to adjust the base plate.Stent static preload: in response to stent the Scaffording after the completion of the pre-pressure, pre-pressure load is not less than 1.2 times the weight of the reinforced concrete beam, pre-pressure sand (or soil) bags preload, the load distribution andCast - weight dis34、tribution, pre-pressure period in each cross set up 15 observation points of the five sections, measured before preloading review fulcrum elevation, sand bags with crane crane into the bracket, pressure test three times the level of increaseupload, the first pressure test weight 40%, 40% in the seco35、nd, third plus all finished, and then observing for 7 d, uninstall the press three times, first test weight of 20%, 40% in the second,three times to finish unloading all, each observation point in every load (uninstall) finished and all finished loading (uninstalled) are to be observed, all finished36、 loading every day observation time after the first observations of consecutive for 7 days in 5mm or less, you can basically stable foundation settlement.2.5 bars, bellows, installation and adjustment backplane qualified strand reinforced Anza Anza time-division two, the first Anza reinforced bottom37、 ribs, floor and ribs pouring concrete the Hou Anzha box top and cantilever pre-Buried reinforced in the pouring box roof when open 1 5 m skylight in the roof stress minimum at (1/4 cross) (each box 1) removal of the box templates, welded steel stent after skylight, and usingthe same label and the b38、ox girder concrete pouring formation.Installation banding finished the backplane reinforced diaphragm skeleton An indulgence, horizontal, vertical bellows strand after you install, and then lashing ribs reinforced.Strand installation procedure: first by its length, the number penetration bellows, an39、d distribution in the ribs position, and then bellows and stress of steel beams in accordance with the coordinates of elements of accurate positioning, the use of reinforced # character frame 1 0 m spacingfixed steel beam, curved parts of the spacing of 5 cm, double check to wear steel beam bellows 40、rupture, interface with rubber or sealing tape wrapped bellows seal, external wire truss, when reinforced with steel beamposition of conflict, reinforced in the steel beam, leads to stomata in the box girder bellows peak (with a small hose leads), install the bellows steel beam, re-check the coordin41、ates of the location to meet the requirements, making adjustments,improve the other ribs and diaphragm reinforced concreting timely strand in the bridge two winch pulling back and forth, pay special attention to prevent the construction of the bellows leakage pulp and flattening caused by the diffic42、ulties of the next process.An indulgence, horizontal, vertical bellows must be in accordance with the drawings given coordinates, can not tamper with the occurrence of prestressed steel reinforced conflict prestressed reinforced the main changes in the position of ordinary reinforcement.2.6 The conc43、rete mixing, transportation, placement, and health (1) concrete mixing by 2 L1000 compulsory mixer unified supply to the mixing station.Ingredients (metrology department has been testing calibration) is controlled by an electronic scale, and in strict accordance with the Central Laboratory of the co44、ncrete mix ratio mixing, 4 sets of 8 m mixer transport, the use of pumped concrete placement and construction, with eight plug-in vibratorvibrators.(2) concrete box girder twice pouring (the first layer is the root of the floor and ribs 50 cm high, the second layer of ribs, roof and cantilevered pla45、te).The box girder bottom and ribs of concrete pouring oblique layer method from low to high end.By low-to high-propulsion.The initial setting of concrete with a wire brush nap, so that the surface is rough and smooth, clean.The combination of quality for concrete bridge deck pavement.The first laye46、r of concrete pouring plug-in vibrators vibrators, vibrating compaction.Each work shift system to take the test block at least five groups.The last layer of the construction of concrete, two sets of test block on the box girder conservation under the same conditions, the coverage of health.2.7 prest47、ressed tension (1) the strength of concrete to meet the design strength of 100%, and the age of 14 d before tensioning.Prestressed Steel pull in strict accordance with the design drawings provided by the tension sequence and tension control stress.Tensioning equipment before use to check and check.(48、2) prestressed box girder of the bridge with post-tensioned prestressing tendons for low relaxation prestressed steel hinge line tensioning process both ends of the tension, the transverse prestressing steel twist longitudinal prestressing strand according to the design drawingstension, one end of l49、ine mining, vertical prestressed reinforced with the beam top surface tension.(3) prestressed tension dual-control, control tensile force, elongation, check the difference of the actual elongation value and theoretical value of elongation to exceed regulatory requirements should be suspended tension50、, identify the reasons for and, and then continue to take measures to adjust the tension.(4) The tensioning device check: tensioning equipment and anchorage supporting the use of inspection and checking before the approach to use, each jack and pressure gauge, pressure cell, dynamometer and other de51、vices, with 1% of reading accuracy.The pressure gauge accuracy should not be less than 1.5.Jack is generally used for more than six months or 200 times, as well as irregularities in the use, re-calibration.(5) stretching production: each prestressed reinforced tag number and plate number or use the 52、number of steel strand shall not kink, twist rotation, shall not be loose, and each strand at each end of the componenteasy to identify.The expected length of the next strand should be the length of the both ends of the work taken into account, the strand tensioned cutting cutting machine with high-53、speed hand wheel, the exposed length of 35 mm.(6) the longitudinal and transverse steel hinge line tension operating procedures as follows: 0 initial stress (10% k) k measurement the Elongation cylinder back to zero, measured back Amount (loading for 2 min).2.8 Duct Grouting (1) grouting ago, blown 54、into the oil-free compressed air clean the pipes, and then containing 0 or 0.01 kg / L lime or calcium hydroxide, rinse with water pipes, and then blow dry with compressed air.(2) was prepared using cement pulp mixer to meet the requirements of the cement slurry.Water added to the mixer, then add th55、e cement, mixed with a mixing agent (if required) after full mixing (grouting shall be subject to filtering,) mixing should be at least 2 minutes until it reaches a uniform consistency so far.Then the pressure pump output tube connected with a grouting tube A Duanxiang.(3) to start the piston pressu56、re pump slurry into the A-side, the exhaust from the B-side, until the B-side vent out of the thick paste of required consistency, turn off the B-side valve, and maintain not less than 0. 5MPaa regulator of the regulator of not less than 2 min, the A-side and then close the valve.(4) 30 for 45 min i57、ntervals, from the B-side grouting, exhaust from the A-side until the A side vent out of compliance with the provisions of the consistency of thick syrup, turn off the A-side valve and maintain not less than 0. 5MPaa regulator of the regulator of not less than 2 min, turn off the B-side valve.(5) Th58、e grouting process, fill out the complete record of grouting, including grouting date of each pipe, the water-cement ratio and mixing materials, grouting pressure, obstacles accident details and the need to complement the work done.(6) The pressure of full-slurry pipeline should be protected, so tha59、t in one day from vibration, structural concrete temperature shall not be less than 5 C within 48 h after the grout injection pipe or insulation measures should be taken; when the daytime high temperature35 C, grouting should be carried out at night.2.9 anchor in order to protect the exposed anchora60、ge will not rust and void when the grouting is completed, the exposed parts of the cleaning, and the face of concrete cutting hair, and steel banding.Anchor steel mesh and set aside the reinforced spot one, and then install the template, pouring concrete.Grouting seal anchor and after the grouting i61、ntensity of 80%, disassemble roof rack.2.10 bracket, removal of the template in the grouting intensity of 90% and removal of all stents after the completion of the seal anchor.Removal of the stent from a cross symmetry to the two uniform demolished, so that the weight of the bridge symmetry, the ave62、rage bear evenly on both ends of the bearing, prevention of box girder due to uneven cracks.The base mold is removed to prevent the appearance quality of the damaged box girder.3 Conclusion During the construction process, it should be according to drawings, construction equipment, on-site construction conditions, and other aspects taken into account.Seriously and carefully done every construction process, and take effective measures to ensure project quality, cost savings and to ensure construction safety.撤消修改