QC小組薄壁空心墩墩滑模施工外觀質(zhì)量及垂直度控制

1、部 門:QC小組：施工技術(shù)小組發(fā)表人:日 期:2012年10月21日 QC小組薄壁空心墩墩滑模施工外觀質(zhì)量及垂直度控制2022/9/40工程概況2022/9/41液壓滑升模板簡介 液壓滑升模板是一種具有自升設(shè)備，能隨砼的澆筑自行向上滑升的模板裝置，由模板系統(tǒng)、操作系統(tǒng)和液壓滑升系統(tǒng)組成，利用液壓千斤頂沿支承桿（支承桿埋于砼中）向上爬升，帶動整個滑模裝置邊澆筑邊上升的一種連續(xù)成型的快速施工方法?；Ｊ┕げ挥弥Ъ?，不需周期拆裝，用材省，勞力消耗少，施工進(jìn)度快，結(jié)構(gòu)整體性好，安全可靠，適用于現(xiàn)場澆筑高聳的鋼砼結(jié)構(gòu)，但模板一次性投資較大。2022/9/42（一）小組概況（三）確定目標(biāo)值主要內(nèi)容（二）現(xiàn)

2、狀調(diào)查（五）確定主要原因（四）主要原因分析（六）制定對策（八）鞏固措施（七）效果檢查（九）遺留問題及今后打算2022/9/43小組概況組建時間2011.9.151.活動課題：運用QC方法確保薄壁空心墩滑模施工質(zhì)量人 數(shù)小組8人 平均年齡33 歲 活動次數(shù)15 次活動時間2012.1-2012.10人均接受QC教育160學(xué)時巴基斯坦橋梁項目 QC小組課題類型現(xiàn)場型注冊登記2022/9/442.人員結(jié)構(gòu)及文化技術(shù)素質(zhì)結(jié)構(gòu)、組內(nèi)分工2022/9/45選題理由1）薄壁空心墩混凝土外觀質(zhì)量控制 薄壁空心墩液壓滑模施工具有較強(qiáng)的連續(xù)性，施工進(jìn)度快，施工時對混凝土外觀影響較大。通過施工觀測外觀質(zhì)量欠佳，需要

3、采取措施改進(jìn)砼外觀質(zhì)量。2）薄壁空心墩混凝土施工平整度及垂直度控制 薄壁空心墩液壓滑模施工具有一定的專一性，液壓滑模施工的重點是施工方案的選擇、人員的組織培訓(xùn)及模具的配備。水平及垂直度的控制及糾偏是滑模工程中的一個難點，也是一個質(zhì)量重點監(jiān)控項目，由于存在工藝粗疏、管理隨意，形成平整度及垂直度超差的的質(zhì)量問題。2012年8月以前本工程質(zhì)量狀況小組通過查證2012年8月以前施工薄壁墩，調(diào)查數(shù)據(jù)如下：本工程已施工的兩個薄壁空心墩合格率表 調(diào)查顯示已施工薄壁空心墩的平整度及垂直度平均合格率為81%,低于項目要求的95%。且外觀較差。分類外觀平整度垂直度27號 差78%79%28號85%82% 平均81

4、% 選定課題 提高混凝土外觀質(zhì)量，糾正平整度及垂直度偏差。2022/9/46 二、現(xiàn)狀調(diào)查2012年07月10日10月20日，QC小組成員對現(xiàn)場施工的第24、26、27、28號薄壁空心墩滑模的外觀、平整度及垂直度進(jìn)行觀測統(tǒng)計，外觀為目測，平整度為2米水平尺檢查，垂直度檢查觀測方法為用精密全站儀觀測模板四角頂點，水準(zhǔn)儀配合定標(biāo)高。結(jié)果如下表。因此得出結(jié)論是先施工的27、28號各項指標(biāo)明顯差于改正后的24、26號，為達(dá)到要求，需要按QC小組加強(qiáng)公關(guān)，持續(xù)改進(jìn)。點號外觀平整度 垂直度部位垂直度偏差（L/1000）點號外觀平整度 垂直度部位垂直度偏差（L/1000）24較好2L=-0.54.5527較

5、差4L=-0.515.115241L=-0.56.742712L=-0.515.114244L=-0.57.97277L=-0.516.316245L=-0.59.19274L=-0.516.316244L=-0.510.39275L=-0.517.513263L=-0.511.512284L=-0.517.515264L=-0.512.712285L=-0.518.721263L=-0.512.7132813L=-0.518.720264L=-0.513.9132812L=-0.520.017263L=-0.513.9142811L=-0.520.0182022/9/47 目標(biāo)值要做好過程控

6、制，保證滑模過程薄壁空心墩平整度、垂直度不超出允許范圍，即垂直度合格率由活動前的81%提高到95%,混凝土外觀大幅改善。見下圖：設(shè)定目標(biāo)小組活動目標(biāo)柱狀圖合格率 95% 90% 81% 80% 60% 40% 10% 0 QC活動前 活動后目標(biāo)值 100% 2022/9/48目標(biāo)論證 本項目部人員質(zhì)量意識較強(qiáng)，技術(shù)素質(zhì)較好，學(xué)習(xí)積極性較高 。 本項目部人員團(tuán)結(jié)務(wù)實，具有不達(dá)目的不罷休的敬業(yè)精神，工作熱情高。 根據(jù)施工組織、工藝及現(xiàn)場施工人員的經(jīng)驗，要達(dá)到預(yù)期目標(biāo)是可以實現(xiàn)的。2022/9/49原因分析 通過現(xiàn)狀調(diào)查及現(xiàn)場觀測，小組于2012年10月7日召開小組會議，群策群力，對平整度、垂直度不

7、合格的點位展開充分討論，找出了影響合格率的問題，并繪制了因果分析樹圖。砼外觀差平整度及 垂 直度超差人員材料機(jī)具方法責(zé)任心及質(zhì)量意識差，施工技能不高，技術(shù)培訓(xùn)少，未進(jìn)行交底模板變形老化，支撐桿數(shù)量不夠。用于觀測的全站儀需要精準(zhǔn)校正混凝土振搗方法不對，單一的振搗一側(cè)環(huán)境操作臺上人員物體等荷載分布不均勻混凝土澆筑方法不規(guī)范，單一的進(jìn)行一側(cè)澆筑油壓千斤頂質(zhì)量不合格高程數(shù)據(jù)，垂直度測量數(shù)據(jù)失真單一側(cè)受到混凝土荷載和外在振搗力影響，平臺傾斜平臺傾斜模板不平整，每側(cè)爬升不一致，導(dǎo)致操作平臺傾斜每側(cè)爬升不一致，導(dǎo)致操作平臺傾斜分析樹圖2022/9/410 要因確認(rèn)通過分析樹圖，小組成員對各個影響因素進(jìn)行了討

8、論，確認(rèn)要因。要因確認(rèn)一：人員驗證方法：1.查驗現(xiàn)場交底記錄及培訓(xùn)記錄；2.現(xiàn)場隨機(jī)抽取操作工人，進(jìn)行專業(yè)知識提問。驗證結(jié)果：1.交底記錄及培訓(xùn)記錄齊全；2.操作工人掌握專業(yè)操作理論知識并具有責(zé)任心。結(jié)論：非要因要因確認(rèn)二：材料驗證方法：查驗圓鋼質(zhì)量合格證及復(fù)試報告。驗證結(jié)果：有圓鋼質(zhì)量合格證且均合格。結(jié)論：非要因要因確認(rèn)三：機(jī)具驗證方法：1.查驗油壓千斤頂質(zhì)量合格證；2.查驗全站儀、水準(zhǔn)儀校驗合格證。儀器是否滿足檢查要求，增加精準(zhǔn)儀器進(jìn)行檢查。3.目測模板平整度，很差。驗證結(jié)果：1.有油壓千斤頂質(zhì)量合格證且合格；2.有合格的儀器校驗 合格證已過期。3.需要更換新模板。結(jié)論：是要因施工人員現(xiàn)場

9、教育培訓(xùn)2022/9/411 要因確認(rèn)要因確認(rèn)四：方法驗證方法：1.現(xiàn)場查驗操作工人對混凝土澆筑、振搗的合格性和規(guī)范性；2.桁架滑模控制點檢查，是否滿足施工要求；抽查模板中線檢查方法及頻率。驗證結(jié)果：1.對三個班次的混凝土振搗進(jìn)行查驗，混凝土振搗均勻、規(guī)范；對三個班次的混凝土澆筑方法進(jìn)行查驗，發(fā)現(xiàn)有兩個班次的工人混凝土澆筑的方法不規(guī)范，單一的對某一部位和區(qū)域澆筑而忽略了其他部位，導(dǎo)致垂直度超差；2.控制點過少，檢查頻率過低，方法單一。結(jié)論：是要因要因確認(rèn)五：環(huán)境驗證方法：現(xiàn)場查驗操作平臺荷載分布情況。驗證結(jié)果： 1.對三個班次的操作平臺荷載分布情況進(jìn)行查驗，上部分布振動棒4臺、電焊機(jī)2臺，液壓

10、控制臺1臺及鋼筋等主要設(shè)備和材料，且明顯分布于一側(cè)。2.操作工人共11人分布在同一側(cè)進(jìn)行混凝土澆筑。很明顯，操作臺一側(cè)由于荷載比另一側(cè)大，導(dǎo)致該側(cè)傾斜，澆筑完畢的混凝土筒壁垂直度超差。結(jié)論：是要因增加激光對中器檢查 平整度檢查2022/9/412 制定對策針對上述要因，通過小組分析討論，制定如下對策：2022/9/413 實施一：細(xì)化施工方案并制定專項方案在原有滑模施工方案（2012.07.1編制）的基礎(chǔ)上進(jìn)行細(xì)化，編制補(bǔ)充專項施工方案，保證薄壁空心墩施工標(biāo)準(zhǔn)規(guī)范。M/s XINJIANG BEIXIN,Road & Bridge Construction Co. Ltd.,House No.

11、 16, Street 25th,F-6/2, Islamabad.Kind Attn.: Mr. Wang Mingjiang, Project Manager.Contract No. HW-RHB-FB-2012-3 dated April 8, 2012.Reference Letter: 3366/037/ZM/A-01/0335 dated Sept. 19, 2012.Subject: DISLOCATION OF TOP OF PIERS AT GRIDS 27 AND 28Sir, The slipforming method of construction is diffe

12、rent than conventional formwork system, as the continuous movement of formwork does not allow use of tie bolts as used in conventional formwork. Higher slump and flowing concrete will allow less vibration in form. The tolerances allowed in slipforming form of construction are also different than con

13、ventional formwork construction. The dislocation of top of Pier # 27 & 28 happened due to the following reasons: 1.The centerline of Pier 28 got disturbed at 1st Diaphragm due to changed made in the slip formwork to accommodate it to allow slipforming beyond 1st Diaphragm. We requested for reestabli

14、shing the centerline after the dislocation was not reducing, but were not able to get the centre line reconfirmed. Thus, the dislocation remained even though we tried to bring it back by moving one side of forms more than the other. In Pier # 27 the centre was reconfirmed before start of slipform af

15、ter 1st Diaphragm, giving us more control on alignment of slipform. 2.As requested in our Concreting method and Method Statement for slipform submitted earlier, we required concrete slump greater than 150 mm and flowing concrete for placing the forms. On many occasions we had place concrete that was

16、 stiff and slump was below 150 mm, which was also flowed in chutes with great difficulty. The result of placing concert of this nature was that, it stiffened quickly in forms i.e. reaching initial setting well before it leaves below the forms. The concrete not being plastic in forms does not allow a

17、djustment in wall dimension as we desire and the difference will remain or increase. Another problem that we faced in Pier #27 was due to concrete not being plastic in forms on one side of Pier while other side remained plastic it stiffened and grabbed the recovery tubes attached to Jacks. This caus

18、ed the level difference in slipform thus causing the plumbs to go out of centre axis. 3.As mentioned in point 2 above, the delay in concrete of being received on site after ordering it caused the top layer to stiffen instead of remaining plastic for new layer to be placed over it. This caused adjust

19、ment of forms difficult as the concrete in forms was not in plastic stage.對策實施 The rectification for the above mentioned reasons we are making following changes. 1.In Pier # 26, we have taken the outer coordinates as well as centre line of Pier on Pile cap. These centre line on all four side will be

20、 transferred to Pier wall and will be shifted on Pier wall as slipform rises. The centre on the forms will be rechecked with these centre lines at 6 hourly intervals, if there are any variation (which is possible due the moving nature of slipforms and tolerances allowed as Per ACI 117) they will be

21、corrected accordingly. The centre line being shifted upward along the Pier wall will also be rechecked using laser instrument with the original mark on the bottom. Also, as in earlier Piers the Main Contractor will continue to check the co-ordinates of the pier each day. 2.As mentioned above the sto

22、ppage at Diaphragms caused the messing up of centre line due to changes made in slipforms from diaphragm to diaphragm (removal of yokes and changes in forms). We have decided to slipform the pier from pile cap to pier top in one go and cast diaphragms after dismantling of slipform. This will also sp

23、eed up pier construction as casting of diaphragm holds up slipforms for eight days, which increases the time of Pier construction by slipform. 3.When the order is placed for concrete for placing in slipforms, we have estimated that by the time concrete arrives we will have space in forms for its pla

24、cing and the concrete being placed will be able to bond with previous layer with limited vibration. If concrete has less slump or is stiff, excessive vibration will be carried out, which will affect concrete finish and dimension adjustment made difficult. So, Slump more than 150 mm and flowing concr

25、ete is required for placing in slipform. Thus, time supply of concrete is also requested to allow us to keep the top concrete layers in plastic state and allow adjustments of forms with ease. The taking of centre line along the sides of Pier in Pier 26 will allow us to control the dimension of Pier

26、with tolerances for slipforming (as per ACI 117). Also, the other point of concrete being plastic in forms and slump of 150 mm at placing time in forms, with less vibration, will help in finish as well forms adjustment in slipform.Thanking you for your co-operation.For Construction Equipment Service

27、s (Pvt.) Limited(NASEER A. KHAN) Chief Executive2022/9/414薄壁空心墩施工工藝2022/9/415實施二：加強(qiáng)職工質(zhì)量意識教育，并更換新模板，增強(qiáng)技術(shù)水平提高外觀質(zhì)量。約巴方員工進(jìn)行施工質(zhì)量談話，提高質(zhì)量意識改進(jìn)施工工藝。施工中的26號墩，對外觀質(zhì)量進(jìn)行嚴(yán)格控制，配備專人進(jìn)行修飾及養(yǎng)護(hù)作業(yè)。更換新模板2022/9/416實施三：多項控制，加強(qiáng)觀測，及時發(fā)現(xiàn)問題并現(xiàn)場改正。確保薄壁空心墩施工過程中的坐標(biāo)準(zhǔn)確。工作中管水平觀測確?；Ｌ幱谒綘顟B(tài)，防止偏位激光對中器定時檢查滑模位置垂球檢查豎直度全站儀檢查模板坐標(biāo)點檢查（每天兩次）2022/9/417實施四：混凝土澆筑循序漸進(jìn)，防止出現(xiàn)偏差。鋼筋及千斤頂進(jìn)行刻度表識，升模及澆筑嚴(yán)格按刻度進(jìn)行施工。2022/9/418實施五：計算操作臺荷載并制定專項方案 制定了專項方案，主要內(nèi)容是優(yōu)化平臺荷載。平臺上的荷載主要有：振動棒4個、氣割及電焊機(jī)各1臺、液壓操作臺1臺、操作人員11個?？傊亓繛椋?6X4+85X2+185X1+60X11=1159kg。由于人員是流動