正常下沉(chen)(chen)(chen)時，應(ying)自中間向(xiang)刃(ren)(ren)腳處均勻對稱除土。排水(shui)除土下沉(chen)(chen)(chen)的(de)(de)(de)沉(chen)(chen)(chen)井(jing)(jing)底節(jie)(jie)，其設計支承位置的(de)(de)(de)土，應(ying)在分層除土中同時挖除。由多個井(jing)(jing)室(shi)(shi)組成(cheng)的(de)(de)(de)沉(chen)(chen)(chen)井(jing)(jing)，應(ying)控制(zhi)各井(jing)(jing)室(shi)(shi)之間除土面(mian)(mian)的(de)(de)(de)高(gao)差，并避(bi)免(mian)內隔墻底部(bu)下沉(chen)(chen)(chen)時受阻(zu)。沉(chen)(chen)(chen)井(jing)(jing)接(jie)(jie)高(gao)前應(ying)盡(jin)量(liang)糾正前一節(jie)(jie)的(de)(de)(de)傾斜，頂(ding)管施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)沉(chen)(chen)(chen)井(jing)(jing)，接(jie)(jie)高(gao)一節(jie)(jie)的(de)(de)(de)豎向(xiang)中軸線(xian)(xian)應(ying)與(yu)前一節(jie)(jie)的(de)(de)(de)豎向(xiang)中軸線(xian)(xian)重合。水(shui)上沉(chen)(chen)(chen)井(jing)(jing)接(jie)(jie)高(gao)時，井(jing)(jing)頂(ding)露(lu)出(chu)水(shui)面(mian)(mian)不(bu)應(ying)小于1．5m。地(di)(di)面(mian)(mian)上沉(chen)(chen)(chen)井(jing)(jing)接(jie)(jie)高(gao)時，污水(shui)沉(chen)(chen)(chen)井(jing)(jing)施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)，井(jing)(jing)頂(ding)露(lu)出(chu)地(di)(di)面(mian)(mian)不(bu)應(ying)小于o．5m。接(jie)(jie)高(gao)前不(bu)得(de)掏(tao)空刃(ren)(ren)腳，避(bi)免(mian)沉(chen)(chen)(chen)井(jing)(jing)傾斜。沉(chen)(chen)(chen)井(jing)(jing)基礎施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)一般可(ke)分為早(zao)地(di)(di)施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)、水(shui)中筑島及浮運沉(chen)(chen)(chen)井(jing)(jing)三種。施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)前應(ying)詳(xiang)(xiang)細了解場(chang)地(di)(di)的(de)(de)(de)地(di)(di)質和水(shui)文條件。水(shui)中施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)應(ying)做好河(he)流汛期、河(he)床沖刷、通航及漂流物等調查研究，充分利用(yong)枯(ku)水(shui)季節(jie)(jie)，制(zhi)訂詳(xiang)(xiang)細的(de)(de)(de)施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)計劃及必(bi)要的(de)(de)(de)措施(shi)(shi)(shi)，確(que)保施(shi)(shi)(shi)工(gong)(gong)(gong)(gong)(gong)安全。

井底下(xia)沉(chen)至(zhi)設計標高2．om以上時，應放(fang)慢下(xia)沉(chen)速度，控制井內(nei)除(chu)土(tu)量和除(chu)土(tu)位(wei)置，沉(chen)井施(shi)(shi)工(gong)工(gong)程，以求沉(chen)井平穩下(xia)沉(chen)、正確就位(wei)。沉(chen)井施(shi)(shi)工(gong)前，安徽沉(chen)井施(shi)(shi)工(gong)，應詳細(xi)調查(cha)施(shi)(shi)工(gong)期(qi)間內(nei)的洪汛、凌汛、河(he)床(chuang)沖涮、通航(hang)及漂流物等情(qing)況(kuang)，并根據(ju)(ju)調查(cha)情(qing)況(kuang)制定具體措施(shi)(shi)，確保安全。沉(chen)井下(xia)沉(chen)前，應根據(ju)(ju)設計單位(wei)提供的地質資料決定是(shi)否需要增(zeng)補施(shi)(shi)工(gong)勘探，為編制施(shi)(shi)工(gong)技術(shu)方(fang)案提供準確依據(ju)(ju)。

沉井下(xia)(xia)沉前，應(ying)根據設計單位提(ti)供(gong)(gong)的地質資料決定是否需要增(zeng)補施(shi)工勘探，為編制(zhi)施(shi)工技術(shu)方(fang)案提(ti)供(gong)(gong)準確依據。應(ying)避(bi)免因井外(wai)棄土引(yin)起對沉井結(jie)構的偏壓。應(ying)注意(yi)河床因沖淤引(yin)起的土面高差，必要時可(ke)用(yong)沉井外(wai)棄土來(lai)調整。下(xia)(xia)沉過程中，應(ying)隨時掌握土層變化情況，分(fen)析和檢驗土的阻力與(yu)沉并重力的關(guan)系，選用(yong)有效的下(xia)(xia)沉方(fang)法，并做好下(xia)(xia)沉觀(guan)測(ce)記錄。