由(you)于(yu)水下作業比陸上(shang)工(gong)作條件(jian)復雜(za)，操作技術要求高，因而只有在特殊情況下才采(cai)用。

  水(shui)(shui)下(xia)堵(du)漏清(qing)基 ①建(jian)筑(zhu)物基面(mian)的清(qing)理：當(dang)水(shui)(shui)生物或水(shui)(shui)垢、水(shui)(shui)銹較(jiao)輕時(shi)，用竹刷、鋼絲刷、刮(gua)刀、砍(kan)斧、鑿子或風動砂輪等清(qing)理;較(jiao)重(zhong)時(shi)則(ze)用高速射(she)流水(shui)(shui)清(qing)洗。②基坑清(qing)理：一般由潛水(shui)(shui)員輔以工具進(jin)行;當(dang)工作(zuo)(zuo)面(mian)或工作(zuo)(zuo)量大時(shi)，則(ze)先用挖掘機、挖泥船或氣泵(beng)進(jin)行初步清(qing)理。

  水(shui)(shui)下(xia)鉆(zhan)(zhan)(zhan)孔(kong)(kong)(kong)(kong) 當孔(kong)(kong)(kong)(kong)深(shen)及(ji)孔(kong)(kong)(kong)(kong)徑較小或在豎直(zhi)面上鉆(zhan)(zhan)(zhan)孔(kong)(kong)(kong)(kong)時(shi)，可用(yong)風動鑿巖(yan)機鉆(zhan)(zhan)(zhan)孔(kong)(kong)(kong)(kong)，由(you)潛(qian)水(shui)(shui)員在水(shui)(shui)下(xia)直(zhi)接操作(zuo)。當在閘壩上游進行帷幕補強灌(guan)漿或鉆(zhan)(zhan)(zhan)大(da)孔(kong)(kong)(kong)(kong)徑 孔(kong)(kong)(kong)(kong)時(shi)，一(yi)般采用(yong)設(she)在船(chuan)臺或浮排組成(cheng)的工作(zuo)臺上的回轉鉆(zhan)(zhan)(zhan)機鉆(zhan)(zhan)(zhan)孔(kong)(kong)(kong)(kong)。20世(shi)紀(ji)60年代以來(lai)，歐洲、美洲一(yi)些 和(he)日本(ben)廣(guang)泛采用(yong)了雙套(tao)(tao)管(其外套(tao)(tao)管用(yong)以固定鉆(zhan)(zhan)(zhan)孔(kong)(kong)(kong)(kong)位(wei)置(zhi)，保護鉆(zhan)(zhan)(zhan)具免受(shou)流水(shui)(shui)沖擊;內(nei)套(tao)(tao)管頭部鑲(xiang)有環形(xing)鉆(zhan)(zhan)(zhan)頭，可以鉆(zhan)(zhan)(zhan)透覆(fu)蓋層達(da)到基巖(yan)中)在深(shen)水(shui)(shui)域鉆(zhan)(zhan)(zhan)孔(kong)(kong)(kong)(kong)。