當(dang)出現因沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)自(zi)身重力偏輕(qing)下(xia)(xia)沉(chen)(chen)(chen)(chen)(chen)困難(nan)時(shi)，可(ke)采用(yong)井(jing)(jing)(jing)外高(gao)(gao)壓(ya)射(she)水(shui)、降低井(jing)(jing)(jing)內(nei)水(shui)位(wei)等(deng)方法(fa)下(xia)(xia)沉(chen)(chen)(chen)(chen)(chen)。在結構(gou)受力允(yun)許的條(tiao)件下(xia)(xia)，也可(ke)以采用(yong)壓(ya)重或(huo)接高(gao)(gao)沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)下(xia)(xia)沉(chen)(chen)(chen)(chen)(chen)。沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)施(shi)工前，應詳細調查施(shi)工期間內(nei)的洪(hong)汛、凌汛、河床沖(chong)涮(shuan)、通(tong)航(hang)及(ji)漂流物(wu)等(deng)情(qing)況，并根據調查情(qing)況制(zhi)定具體措施(shi)，確保安全。沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)預制(zhi)完成(cheng)并準確就位(wei)后，開始抽(chou)除墊(dian)木。不論沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)大小(xiao)，此項(xiang)工作均要求在2～4h內(nei)完成(cheng)。抽(chou)除墊(dian)木前，污(wu)水(shui)沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)施(shi)工，應對墊(dian)木分組編(bian)號，準備回(hui)填用(yong)的砂料，測(ce)量刃腳標高(gao)(gao)和沉(chen)(chen)(chen)(chen)(chen)井(jing)(jing)(jing)中線。

沉(chen)(chen)(chen)(chen)井(jing)(jing)(jing)優點：占地(di)面積(ji)小，沉(chen)(chen)(chen)(chen)井(jing)(jing)(jing)基礎施工方(fang)案(an)，不(bu)需要板樁圍護。挖土量(liang)小，對(dui)鄰近建筑的(de)影響比(bi)較小，操作簡便，無須(xu)特(te)殊(shu)的(de)設備。沉(chen)(chen)(chen)(chen)井(jing)(jing)(jing)下沉(chen)(chen)(chen)(chen)時(shi)，不(bu)宜(yi)使用(yong)方(fang)法(fa)。遇(yu)到(dao)石(shi)塊、巖層(ceng)等特(te)殊(shu)情況，經(jing)有關(guan)方(fang)面批準采用(yong)除(chu)土和(he)炮震助沉(chen)(chen)(chen)(chen)方(fang)法(fa)時(shi)，應(ying)嚴格控(kong)制(zhi)(zhi)藥量(liang)。井(jing)(jing)(jing)底下沉(chen)(chen)(chen)(chen)至(zhi)設計標高2．om以(yi)上時(shi)，應(ying)放慢(man)下沉(chen)(chen)(chen)(chen)速度(du)，控(kong)制(zhi)(zhi)井(jing)(jing)(jing)內除(chu)土量(liang)和(he)除(chu)土位置，以(yi)求沉(chen)(chen)(chen)(chen)井(jing)(jing)(jing)平穩下沉(chen)(chen)(chen)(chen)、正(zheng)確就位。

沉(chen)井應用范圍(wei)：當地(di)下(xia)(xia)(xia)水(shui)(shui)(shui)位較高，沉(chen)井施工(gong)，土(tu)(tu)的滲(shen)透性大，易產生涌流或(huo)塌陷的不穩定土(tu)(tu)壤(rang)，可采(cai)(cai)(cai)用沉(chen)井不排(pai)水(shui)(shui)(shui)下(xia)(xia)(xia)沉(chen)和水(shui)(shui)(shui)下(xia)(xia)(xia)澆筑混凝土(tu)(tu)封底。沉(chen)井下(xia)(xia)(xia)沉(chen)施工(gong)有(you)排(pai)水(shui)(shui)(shui)除(chu)(chu)土(tu)(tu)和不排(pai)水(shui)(shui)(shui)除(chu)(chu)土(tu)(tu)兩種方法(fa)。通常采(cai)(cai)(cai)用不排(pai)水(shui)(shui)(shui)除(chu)(chu)土(tu)(tu)的方法(fa)。采(cai)(cai)(cai)用排(pai)水(shui)(shui)(shui)除(chu)(chu)土(tu)(tu)下(xia)(xia)(xia)沉(chen)的方法(fa)要有(you)安(an)全措施，防止發生人身安(an)全事故。在刃腳遇到障礙物的情況下(xia)(xia)(xia)，必須先(xian)清除(chu)(chu)后再下(xia)(xia)(xia)沉(chen)。清除(chu)(chu)方法(fa)是人工(gong)排(pai)除(chu)(chu)，在不能(neng)排(pai)水(shui)(shui)(shui)的情況下(xia)(xia)(xia)，由潔水(shui)(shui)(shui)工(gong)進行下(xia)(xia)(xia)切割(ge)或(huo)者水(shui)(shui)(shui)下(xia)(xia)(xia)。