沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)下(xia)沉(chen)(chen)(chen)時(shi)，不(bu)宜使(shi)用方(fang)法(fa)。遇到(dao)石塊、巖層(ceng)等(deng)特(te)殊(shu)情況，經有關方(fang)面(mian)批(pi)準采用除(chu)土和炮震助沉(chen)(chen)(chen)方(fang)法(fa)時(shi)，應(ying)嚴格控制(zhi)藥量。沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)施工前(qian)，應(ying)詳細調(diao)查(cha)施工期間內的洪汛、凌汛、河床沖涮、通航及漂流物等(deng)情況，并根據調(diao)查(cha)情況制(zhi)定具體措施，確保安全。沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)如發生偏斜必要時(shi)可(ke)以在沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)頂面(mian)施加水平力扶正(zheng)。糾正(zheng)沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)中位(wei)位(wei)置發生偏移的方(fang)法(fa)是(shi)先使(shi)沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)傾斜，然(ran)后(hou)均(jun)勻除(chu)土，使(shi)沉(chen)(chen)(chen)井(jing)(jing)(jing)(jing)底中心(xin)線下(xia)沉(chen)(chen)(chen)至(zhi)設計中心(xin)線后(hou)，再進行(xing)糾偏。

將(jiang)事先(xian)在(zai)(zai)地面(mian)上(shang)用(yong)(yong)鋼筋混(hun)凝土(tu)(tu)制成的(de)井(jing)(jing)筒(tong)形(xing)狀的(de)結(jie)構作為(wei)基坑坑壁的(de)支撐，在(zai)(zai)井(jing)(jing)壁的(de)保護下(xia)(xia)，沉(chen)(chen)(chen)(chen)井(jing)(jing)施(shi)(shi)(shi)工(gong)，用(yong)(yong)機械和人工(gong)在(zai)(zai)井(jing)(jing)內挖土(tu)(tu)，施(shi)(shi)(shi)工(gong)沉(chen)(chen)(chen)(chen)井(jing)(jing)，并在(zai)(zai)其自重作用(yong)(yong)下(xia)(xia)沉(chen)(chen)(chen)(chen)入土(tu)(tu)中(zhong)的(de)結(jie)構物(wu)稱為(wei)沉(chen)(chen)(chen)(chen)井(jing)(jing)。沉(chen)(chen)(chen)(chen)井(jing)(jing)下(xia)(xia)沉(chen)(chen)(chen)(chen)遇(yu)傾(qing)斜巖(yan)層時，沉(chen)(chen)(chen)(chen)井(jing)(jing)施(shi)(shi)(shi)工(gong)工(gong)程，應(ying)(ying)(ying)將(jiang)其表面(mian)松軟巖(yan)層或風(feng)化巖(yan)層鑿去，并盡(jin)量整平，使沉(chen)(chen)(chen)(chen)井(jing)(jing)刃(ren)腳(jiao)的(de)2／3以(yi)上(shang)嵌擱(ge)在(zai)(zai)巖(yan)層上(shang)，嵌入深度(du)小處不(bu)宜小于o．25m。其余未到巖(yan)層的(de)刃(ren)腳(jiao)部(bu)分，可(ke)用(yong)(yong)袋裝混(hun)凝土(tu)(tu)等填塞缺口(kou)。刃(ren)腳(jiao)以(yi)內井(jing)(jing)底(di)的(de)巖(yan)層斜面(mian)應(ying)(ying)(ying)鑿成臺階或榫槽，然后清(qing)渣(zha)封底(di)。沉(chen)(chen)(chen)(chen)井(jing)(jing)下(xia)(xia)沉(chen)(chen)(chen)(chen)前，應(ying)(ying)(ying)根據(ju)(ju)設計單位提(ti)供的(de)地質(zhi)資料(liao)決定是否需要增補施(shi)(shi)(shi)工(gong)勘(kan)探，為(wei)編制施(shi)(shi)(shi)工(gong)技術方案提(ti)供準確依據(ju)(ju)。

應避免因井(jing)(jing)外棄土(tu)引起(qi)對沉(chen)(chen)(chen)井(jing)(jing)結(jie)構的(de)偏壓。應注意(yi)河床(chuang)因沖淤引起(qi)的(de)土(tu)面(mian)高差，必要(yao)時可用(yong)沉(chen)(chen)(chen)井(jing)(jing)外棄土(tu)來調(diao)整(zheng)。沉(chen)(chen)(chen)井(jing)(jing)施(shi)工，沉(chen)(chen)(chen)井(jing)(jing)施(shi)工工藝(yi)流程，實質上就是(shi)將一個在(zai)地面(mian)上事先(xian)澆制好的(de)構筑(zhu)物通過(guo)挖(wa)土(tu)沉(chen)(chen)(chen)入到地下一定深度后成為地下構筑(zhu)物的(de)施(shi)工過(guo)程。沉(chen)(chen)(chen)井(jing)(jing)優點：占(zhan)地面(mian)積小(xiao)，不(bu)需要(yao)板樁(zhuang)圍(wei)護。挖(wa)土(tu)量小(xiao)，對鄰近建筑(zhu)的(de)影響(xiang)比較小(xiao)，操(cao)作簡(jian)便，無(wu)須(xu)特殊的(de)設備(bei)。