一、橋梁建設施工方法有哪些
橋梁施工是橋梁建設的重中之重,施工的質量直接關系到橋梁的使用壽命和工程造價,橋梁施工的方法主要有:
1、支架現澆法
在橋(qiao)(qiao)位處搭設(she)支(zhi)架(jia),在支(zhi)架(jia)上澆筑(zhu)橋(qiao)(qiao)體混凝(ning)土(tu),達到(dao)強度后拆除模板(ban)、支(zhi)架(jia)。現(xian)場(chang)澆筑(zhu)法無需預(yu)制場(chang)地,而(er)且不(bu)(bu)需要(yao)(yao)大型起吊、運輸設(she)備,梁體的(de)主(zhu)筋可不(bu)(bu)中斷,橋(qiao)(qiao)梁整體性好(hao)。它的(de)主(zhu)要(yao)(yao)缺點(dian)是(shi)工期長,施(shi)工質量不(bu)(bu)容易控制;對預(yu)應力混凝(ning)土(tu)梁由(you)于混凝(ning)土(tu)的(de)收縮、徐變引起的(de)應力損失比較大;施(shi)工中的(de)支(zhi)架(jia)、模板(ban)耗用量大,施(shi)工費(fei)用高;搭設(she)支(zhi)架(jia)影(ying)響排洪、通航,施(shi)工期間可能受到(dao)洪水和激流物(wu)的(de)威脅。
2、懸臂施工法
懸(xuan)(xuan)臂(bei)施工(gong)(gong)(gong)法(fa)是(shi)指在(zai)橋(qiao)(qiao)墩兩側設置工(gong)(gong)(gong)作平臺,平衡地逐段向(xiang)跨中(zhong)懸(xuan)(xuan)臂(bei)澆筑(zhu)或拼裝梁段,直至橋(qiao)(qiao)跨結(jie)構(gou)合龍的(de)(de)(de)施工(gong)(gong)(gong)方法(fa)。懸(xuan)(xuan)臂(bei)施工(gong)(gong)(gong)法(fa)具(ju)有許多(duo)突(tu)出的(de)(de)(de)優點,可以(yi)不(bu)(bu)用或少(shao)用支(zhi)架,施工(gong)(gong)(gong)時(shi)不(bu)(bu)影響通航或橋(qiao)(qiao)下交通,并適用于變截面(mian)橋(qiao)(qiao)梁結(jie)構(gou)的(de)(de)(de)施工(gong)(gong)(gong),對(dui)于墩頂承受(shou)(shou)(shou)負彎(wan)矩的(de)(de)(de)橋(qiao)(qiao)梁。施工(gong)(gong)(gong)時(shi)的(de)(de)(de)受(shou)(shou)(shou)力狀態(tai)與建成(cheng)后的(de)(de)(de)受(shou)(shou)(shou)力狀態(tai)基本一(yi)致,因(yin)(yin)而可減少(shao)或節(jie)省施工(gong)(gong)(gong)用材。但是(shi),懸(xuan)(xuan)臂(bei)施工(gong)(gong)(gong)也有其不(bu)(bu)利的(de)(de)(de)一(yi)面(mian),施工(gong)(gong)(gong)技(ji)術要求(qiu)較高,對(dui)于墩梁非(fei)固結(jie)的(de)(de)(de)橋(qiao)(qiao)梁結(jie)構(gou),還(huan)需采取(qu)臨時(shi)固結(jie)措施,因(yin)(yin)而會產生施工(gong)(gong)(gong)階(jie)段體系轉換,此(ci)外,橋(qiao)(qiao)墩在(zai)施工(gong)(gong)(gong)過(guo)程中(zhong)的(de)(de)(de)受(shou)(shou)(shou)力較為不(bu)(bu)利,特別(bie)是(shi)當兩個懸(xuan)(xuan)臂(bei)長度非(fei)對(dui)稱(cheng)時(shi),橋(qiao)(qiao)墩將承受(shou)(shou)(shou)很大的(de)(de)(de)不(bu)(bu)平衡彎(wan)矩。
3、轉體施工法
橋梁轉(zhuan)(zhuan)體(ti)施(shi)工(gong)是(shi)(shi)上世(shi)紀(ji)40年代以后發展起來的(de)一種架橋工(gong)藝,它(ta)是(shi)(shi)在(zai)(zai)河流的(de)兩(liang)岸(an)或適(shi)當的(de)位(wei)置(zhi),利(li)用(yong)(yong)地形(xing)成使用(yong)(yong)簡便的(de)支架先(xian)將(jiang)半(ban)橋預制完成,之后以橋梁結構本身(shen)為轉(zhuan)(zhuan)動(dong)體(ti),使用(yong)(yong)一些機具設備(bei),分別將(jiang)兩(liang)個半(ban)橋轉(zhuan)(zhuan)體(ti)到橋位(wei)軸線位(wei)置(zhi)合(he)攏成橋。其特(te)點(dian)有:可利(li)用(yong)(yong)地形(xing),方便預制;施(shi)工(gong)不影響交通;施(shi)工(gong)設備(bei)少(shao),裝置(zhi)簡單;節省施(shi)工(gong)用(yong)(yong)料。施(shi)工(gong)工(gong)序簡單,施(shi)工(gong)迅速;它(ta)適(shi)合(he)于單跨和三跨橋梁,可在(zai)(zai)深(shen)水、峽谷中(zhong)建橋采用(yong)(yong),同時也適(shi)應在(zai)(zai)平(ping)原(yuan)區(qu)及城市跨線橋。
4、頂推施工法
頂(ding)(ding)推(tui)施(shi)工法是指梁體(ti)在橋臺背后路堤上逐段澆筑或(huo)拼裝(zhuang)(zhuang),并用頂(ding)(ding)推(tui)裝(zhuang)(zhuang)置縱向頂(ding)(ding)推(tui),使梁體(ti)通過(guo)各墩頂(ding)(ding)臨時滑移裝(zhuang)(zhuang)置而就位的施(shi)工方法。
頂(ding)推(tui)(tui)(tui)施(shi)(shi)(shi)工(gong)(gong)時(shi)不影響橋(qiao)下(xia)交(jiao)通,不需要大型起(qi)重設備,也沒有高(gao)空作業,特(te)別(bie)(bie)適合于(yu)城(cheng)市橋(qiao)梁(liang)(liang)(liang)特(te)大跨度橋(qiao)梁(liang)(liang)(liang),長線(xian)引橋(qiao)或立體(ti)交(jiao)叉的(de)施(shi)(shi)(shi)工(gong)(gong);由(you)(you)于(yu)梁(liang)(liang)(liang)段在固(gu)定(ding)場(chang)地上周期性施(shi)(shi)(shi)工(gong)(gong),因(yin)此施(shi)(shi)(shi)工(gong)(gong)質量和施(shi)(shi)(shi)工(gong)(gong)進(jin)度容易保(bao)證(zheng),但是,頂(ding)推(tui)(tui)(tui)施(shi)(shi)(shi)工(gong)(gong)法(fa)也存在一些缺點,對橋(qiao)梁(liang)(liang)(liang)結構的(de)幾何(he)外形限制(zhi)較多(duo),變(bian)截面梁(liang)(liang)(liang)段、曲線(xian)型梁(liang)(liang)(liang)軸(zhou)和變(bian)坡度橋(qiao)梁(liang)(liang)(liang)均無法(fa)采(cai)用(yong)頂(ding)推(tui)(tui)(tui)施(shi)(shi)(shi)工(gong)(gong);由(you)(you)于(yu)頂(ding)推(tui)(tui)(tui)過程中橋(qiao)跨結構的(de)受力不斷變(bian)化,將會增加(jia)梁(liang)(liang)(liang)高(gao)和材料用(yong)量,特(te)別(bie)(bie)是預(yu)應(ying)力鋼筋的(de)用(yong)量;此外,頂(ding)推(tui)(tui)(tui)施(shi)(shi)(shi)工(gong)(gong)最多(duo)也只能有兩個工(gong)(gong)作面,也限制(zhi)了(le)頂(ding)推(tui)(tui)(tui)施(shi)(shi)(shi)工(gong)(gong)的(de)速度。
5、移動模架逐孔施工法
移動(dong)模(mo)架造橋機(ji)是(shi)一種自(zi)帶(dai)模(mo)板,利用承(cheng)臺或墩柱(zhu)作為支承(cheng),對橋梁進行現場澆筑(zhu)的施(shi)(shi)工(gong)(gong)(gong)機(ji)械。其主要(yao)特點:施(shi)(shi)工(gong)(gong)(gong)質(zhi)量好,施(shi)(shi)工(gong)(gong)(gong)操作簡便,成本低廉等。在(zai)國外(wai),已廣泛地被采用在(zai)公路(lu)橋、鐵(tie)路(lu)橋的連續梁施(shi)(shi)工(gong)(gong)(gong)中,是(shi)較為先進的施(shi)(shi)工(gong)(gong)(gong)方法(fa)。
6、預制安裝法
預制(zhi)安裝法是指把(ba)提前做好(hao)的預制(zhi)梁運輸到施工現場,采用一(yi)定的架(jia)設方法進行安裝、搭(da)設。
二、橋梁施工工藝流程
橋梁建設是一個復雜的工程,進行橋梁施工時,不同施工方法,其工藝流程也是不同的,以支架現澆法為例,橋梁施工的流程步驟(zou)一般是:
1、鉆孔灌注樁施工
施工(gong)準備→測量放(fang)樣→設置護簡(jian)→定位鉆(zhan)架(jia)→鉆(zhan)孔及(ji)第一次(ci)清孔→放(fang)鋼筋籠、導(dao)管、二次(ci)清孔→灌注水下砼(tong)→測砼(tong)面標(biao)高→拆(chai)導(dao)管結束。
2、擴大基礎施工
施工準備(bei)→測量放樣→圍堰抽水→開挖基(ji)坑→檢測基(ji)坑尺寸→立模→砼拌和澆筑(zhu)→養護。
3、承臺墩身施工
施工準備(bei)→測量放樣→安裝模板→鋼筋(jin)綁扎→分層(ceng)澆筑砼。
4、系梁、立柱、蓋梁施工
(1)系梁施工(水中)
施工(gong)準(zhun)備→圍堰抽水→安裝底(di)模(mo)和側模(mo)板→鋼筋綁扎→澆(jiao)筑砼養護。
(2)立柱施工
施工(gong)準備→立腳手支(zhi)架→綁扎鋼筋→安裝模板(ban)→澆筑砼養(yang)護(hu)。
(3)蓋梁施工
施工準(zhun)備→支架(jia)搭設→鋪(pu)設底板→綁(bang)扎鋼筋(jin)→安裝(zhuang)側模→澆筑砼養(yang)護→拆除支架(jia)。