土建項(xiàng)目冬季施工-中英對(duì)照
本項(xiàng)目施工周期跨越北方初春和冬季兩個(gè)嚴(yán)寒季節(jié),周密的冬季施工措施是整個(gè)項(xiàng)目工程質(zhì)量的有力保障.
第一節(jié) 冬季施工部署
1､冬施責(zé)任分工,見下圖.
冬施責(zé)任分工
2､提前編制鋼結(jié)構(gòu)､土建､和裝修施工冬施方案,并組織施工管理人員和工人進(jìn)行培訓(xùn).
3､編制防火預(yù)案,檢查各樓層消防水管和滅火器,對(duì)管理人員和工人進(jìn)行防火知識(shí)培訓(xùn).
第二節(jié) 技術(shù)和材料準(zhǔn)備
1､在冬期施工前完成鋼結(jié)構(gòu)冬季焊接工藝評(píng)定.
2､要求混凝土供應(yīng)公司､試驗(yàn)室要做好冬期混凝土､砂漿所摻外加劑的復(fù)試試配工作,提前做好負(fù)溫養(yǎng)護(hù)混凝土的配合比試驗(yàn).
3､冬施材料､機(jī)具準(zhǔn)備
冬施前準(zhǔn)備:加熱器(100臺(tái))､電子溫度計(jì)(1個(gè))､電子測(cè)溫儀(4個(gè))､阻燃草簾被､聚苯板和塑料布(各6000m2),見下圖.
電子測(cè)溫計(jì) 阻燃草簾被
試模 混凝土測(cè)溫計(jì)
冬施材料準(zhǔn)備
4､現(xiàn)場(chǎng)外露水管､消防管保溫,見下圖.
現(xiàn)場(chǎng)外露臨水管､消防管保溫
5､大型機(jī)械要做好冬期施工所需油料的儲(chǔ)備和工程機(jī)械潤(rùn)滑油的更換､補(bǔ)充以及其它檢修保養(yǎng)工作,以便在冬施期間運(yùn)轉(zhuǎn)正常.
第三節(jié) 土建防凍要點(diǎn)
1､重點(diǎn)部位保溫措施
(1)沖壓平臺(tái)基礎(chǔ)和水泵房地下室等混凝土保溫
大體積混凝土采用綜合蓄熱養(yǎng)護(hù)法.
混凝土澆筑前,用鐵絲在大鋼模背面固定5cm聚苯板+2層塑料布.
混凝土達(dá)到臨界強(qiáng)度(>4MPa)后,拆除鋼模板并利用穿墻螺桿和鐵絲在混凝土表面固定一層塑料布和兩層阻燃草簾被.
地板混凝土保溫
(2)室內(nèi)土方回填
回填前,徹底清理基底冰水和雜物.
回填土料不含凍土塊.
土方回填時(shí)地下室結(jié)構(gòu)已經(jīng)施工完畢,在于大氣連通的大門洞設(shè)置防風(fēng)門簾,有利于提高室內(nèi)溫度,當(dāng)室內(nèi)氣溫小于0oC時(shí),暫停回填作業(yè)采用分層回填,每層厚度不超過20cm,并采用人工+機(jī)械夯實(shí).
(3)室外土方開挖和回填
對(duì)開挖管溝的側(cè)邊和基槽覆蓋2層草簾被保溫.
采用分層夯實(shí)回填法,每層厚度不大于20cm.
暫停作業(yè)時(shí),對(duì)表面土覆蓋2層草簾被+塑料布進(jìn)行保溫防雨雪.
2､混凝土測(cè)溫
(1)測(cè)溫起始時(shí)間:室外日平均溫度5d穩(wěn)定低于5℃即應(yīng)開始測(cè)溫.測(cè)溫工作內(nèi)容:包括大氣､原材､入模和養(yǎng)護(hù)溫度.
（2） 測(cè)溫點(diǎn)布置:測(cè)溫點(diǎn)沿梁每3m一個(gè)且每跨至少2個(gè),樓板每15m2一個(gè),柱頭､柱腳各一個(gè),剪力墻延軸線布置3點(diǎn)(每點(diǎn)在墻頂和墻腳分別距上下邊緣30-50cm布置一個(gè)).
（3） 測(cè)溫頻率:大氣溫度在7:30,14:00､21:00各測(cè)一次,且每班三次.摻防凍劑的混凝土澆筑后臨界強(qiáng)度達(dá)到之前每2h測(cè)溫一次,臨界強(qiáng)度達(dá)到之后每6h測(cè)溫一次.
（4） 測(cè)溫?cái)?shù)據(jù)處理:每次溫度測(cè)定后輸入計(jì)算機(jī),自動(dòng)生成溫度曲線和混凝土強(qiáng)度計(jì)算值,詳見下圖.
測(cè)溫及數(shù)據(jù)處理
3､鋼筋防凍注意點(diǎn)
(1)在負(fù)溫條件下使用的鋼筋,施工時(shí)應(yīng)加強(qiáng)檢驗(yàn).遇雪天時(shí),綁扎好的鋼筋要用塑料布遮蓋嚴(yán)密,防鋼筋表面結(jié)冰霜.澆筑混凝土前及時(shí)將冰､雪等清理干凈.
(2)在負(fù)溫條件下局部鋼筋的焊接,應(yīng)有遮擋棚,溫度不得低于-20℃,焊后的接頭嚴(yán)禁立刻碰到冰雪.
4､混凝土防凍注意點(diǎn)
(1)在澆筑前,要清除模板和鋼筋上的冰雪和污垢.
(2)在施工縫處接著澆筑混凝土?xí)r,應(yīng)先除掉水泥薄膜和松動(dòng)石子,濕潤(rùn)沖洗干凈,待已澆筑的混凝土強(qiáng)度高于1.2Mpa時(shí)允許繼續(xù)澆筑.
(3)混凝土澆筑后應(yīng)在裸露混凝土表面采用塑料布､草簾等材料覆蓋并進(jìn)行保溫;對(duì)邊､棱角部位的保溫厚度應(yīng)增大到面部位的2~3倍,并壓緊填實(shí)､周圈封好;保溫層要干燥;混凝土養(yǎng)護(hù)期間應(yīng)防風(fēng)防失水.在白天正溫時(shí)進(jìn)行測(cè)量放線,放線必須掀開保溫材料時(shí),要盡量減少掀開面積,放完線后應(yīng)立即覆蓋.
(4)保證混凝土出機(jī)溫度不低于15℃,入模溫度不低于5℃.
(5)冬施混凝土要比常溫下增設(shè)兩組試塊同條件試塊,并填寫混凝土攪拌記錄.其中一組試塊用于抗凍臨界強(qiáng)度測(cè)試,約3~7天,應(yīng)與測(cè)溫結(jié)合起來.在結(jié)構(gòu)混凝土溫度降到抗凍劑規(guī)定溫度前,計(jì)算混凝土強(qiáng)度是否超過抗凍臨界強(qiáng)度4N/mm2(氣溫不低于-15℃時(shí)),如達(dá)不到則應(yīng)增加保溫､加熱養(yǎng)護(hù)等措施,使受凍面強(qiáng)度超過臨界強(qiáng)度.另一組試塊轉(zhuǎn)入常溫養(yǎng)護(hù)28d.
Chapter Two Winter constructions
The construction period of the project is across two cold seasons of early spring and winter in northern area. Therefore, a well-planed winter construction measure shall be the effective protection for the quality of the entire projects.
Section I Construction assignment in winter
1. Winter construction division of responsibilities is as follows.
項(xiàng)目經(jīng)理（總負(fù)責(zé)）
總工（冬施工方案，措施）
現(xiàn)場(chǎng)經(jīng)理（現(xiàn)場(chǎng)實(shí)施，監(jiān)控）
物資經(jīng)理（材料準(zhǔn)備，供應(yīng)）
技術(shù)部（方案措施編制）
工程部（現(xiàn)場(chǎng)監(jiān)督實(shí)施）
物資部（物資購(gòu)買，供應(yīng)） Project Manager (overall responsibility)
Chief Engineer (winter construction plan, measures)
Site Managers (field implementation, monitoring)
Materials Manager (material preparation, supply)
Technology (program measures compilation)
Engineering Department (site monitoring implementation)
Materials Department (material purchase, supply)
Winter construction responsibility assignment
2. Prepared the winter construction plan of steel structure, civil and decoration in advance, and organize the training program for the administrative stuff and workers of construction.
3. Prepared the fire plans, check the fire hoses and fire extinguishers on each floor, and organize the training program of fire safety for managers and workers of construction.
Section II Technology and materials preparation
1. Finish the winter welding technology evaluation of steel structure before the winter construction.
2. Check the reexamining and trial operation of winter concrete and mortar admixtures of concrete supply company and laboratory; finish the concrete mix test of concrete curing in negative temperature in advance;
3. Winter construction materials and equipment preparation
Preparation for winter construction: heater (100 units), electronic thermometer (1), electronic thermo-detector (4), anti-flaming straw cover, polystyrene board and plastic cloth (6000m2 respectively), see the following picture;
Electronic thermo-detector Anti-flaming straw cover
試模 Die trial Concrete thermo-detector
Winter construction material preparation
4. On-site exposed pipeline and fire pipe insulation; see the following picture.
On-site exposed pipeline and fire pipe insulation
5. Prepare the replacement, supplement and other repair and maintenance work of fuel oil reserve and engineering machinery lubricating oil of the large machinery in winter, so as to ensure the normal operation of the facilities during the winter construction.
Section III Main points of antifreeze measures of civil construction
1. Insulation measures of key positions
(1) Concrete insulation of punching platform foundation and the basement pump room;
● Mass concrete applies the comprehensive thermal storage method.
● Before concrete pouring, fix 5cm layer of polystyrene board and 2 plastic cover with steel wire in the back of a large steel mould.
● After the concrete reaches a critical strength (> 4MPa), remove the steel mould and fix use through the wall of steel and wire screw in the concrete surface a layer plastic sheeting and two layers of flame-retardant straw cover.
Floor concrete keeping warm
(2)Indoor earthwork backfill
● Before backfilling, completely clear up frozen water and incidental of foundation base.
● The backfilling soil does not have the frozen soil;
● The construction of basement structure has already completed at the time of earthwork backfill. The windproof curtain shall be located in the main opening where the atmosphere feeds through, so as to improve indoor temperature; when the indoor temperature is lower than 0oC, suspend the backfill work.
● Adopt the method of backfilling in layer, the thickness of each layer shall not exceed 20cm, and applies the manual and machinery tamping.
(3) Excavating and backfilling in outdoor earthwork
● Apply the insulation measure to the excavation trench and cover 2 layers of grasses curtain on the base trough.
● Adopt the method of backfilling in layer, the thickness of each layer shall not greater than 20cm.
When the construction work is suspended, cover the surface soil cover grass curtain with 2 layers + plastic cover for keeping warm.
2. Measuring the concrete temperature
(1)Initial time of temperature measuring: start to measure the temperature while the average outdoor temperature of the 5d is stabilized lower than 5 degrees Centigrade. Temperature measuring includes: atmosphere, raw material, in-mould and curing temperature.
(2) Arrangement of temperature measuring area: temperature measuring area shall be located along roof beams every 3m and at least 2 temperature measuring area shall be arranged; each floor shall have one temperature measuring area every 15m2, and each column cap and post foot shall have one temperature measuring area respectively; the shear wall shall arrange 3 temperature measuring area alone the axis (each temperature measuring area shall be located on the top of the wall or the foot of the wall about 30-50cm away from upper and lower edge respectively).
(3) Frequency of temperature measuring: measure the atmosphere temperature at 7:30, 14:00 and 21:00 respectively, and three times of each shift. Measure the concrete temperature 2h before the concrete reaches the critical strength, which mixed with antifreeze after pouring; measure the concrete temperature 6h after reaches the critical strength.
(4) Data processing of temperature measuring: Input the measured data into computer, which shall be automatically illustrated as temperature curve and calculating value of concrete strength; details as shown in the following picture.
Data processing and temperature measuring
混凝土測(cè)溫 Concrete temperature measuring
測(cè)溫輸入電腦 Input the temperature data into the computer
生產(chǎn)測(cè)溫曲線 Production temperature measuring curve
3. Notice of reinforcing bar anti-freezing
(1)The reinforcing bar used under the negative temperature, it shall strengthen the inspection procedure in construction. In snowing weather, the fixed reinforcing bar shall be tightly covered with the plastic cloth for preventing ice cover and frosting on the reinforcing bar surface. Clean the ice and in time before the concrete pouring.
(2)The welding of some reinforcing bar under negative temperature shall equip with shelter canopy, and the temperature shall not be lower than -20 degrees Centigrade; the joints after welding shall not contact the ice and snow at once.
4. Notice of concrete anti-freezing
(1) Before concrete pouring, remove the snow and dirt on the template and reinforcing bar.
(2) When continue the concrete pouring in the construction joint area, remove the cement cover and loosed stone at first, rinse moistly well, when the intensity of pouring concrete is higher than 1.2Mpa, then continue the pouring process.
(3) The concrete surface after pouring shall be covered with plastic cloth, grass curtain for keeping warm; the thickness of concrete insulation in opposite side and raised angle position shall be 2 times of the surface area, tightly compressed and well covered; The insulation layer will be dry; The concrete shall be protected from wind and water losses in concrete curing. Apply the survey layout when warm in the daytime; when the survey layout need to raise the insulation layer, it shall be covered with immediately after the survey layout finished, and reduce the opening area as far as possible.
(4) Ensure the temperature of the concrete from machine is not lower than 15 degrees Centigrade; the in-mould temperature of concrete shall not be lower than 5 degrees Centigrade.
(5) The concrete construction in winter shall arrange additional two groups of testing piece than the construction under the normal atmospheric temperature; and fill in the concrete mixing record. One group of testing piece shall be used for critical strength test of anti-freezing, which shall take 3-7 days together with temperature measuring. Before the temperature of structure concrete is lower to defined temperature of antifreeze agent, calculate whether the concrete strength excess the critical strength of freeze 4N/mm2 (the temperature shall not be lower than - 15 degrees Centigrade); otherwise, it shall take the insulation and curing measure to keep worm; and ensure the intensity of cold surface exceed the critical strength. Another group of testing piece shall enter into the normal atmospheric temperature and maintains for 28d.
2013.1.30