開(kai)挖深(shen)度(du)超過地(di)下(xia)水(shui)(shui)(shui)埋深(shen)時(shi)，為(wei)(wei)保證土方施工的順利進行(xing)、確保土方邊坡的穩定，需將地(di)下(xia)水(shui)(shui)(shui)位降(jiang)到(dao)基礎埋置深(shen)度(du)以(yi)下(xia)，這項工作(zuo)就(jiu)稱為(wei)(wei)青島工程降(jiang)水(shui)(shui)(shui)。降(jiang)低地(di)下(xia)水(shui)(shui)(shui)位的方法，一般可分為(wei)(wei)集水(shui)(shui)(shui)坑降(jiang)水(shui)(shui)(shui)和(he)井點降(jiang)水(shui)(shui)(shui)兩(liang)大類(lei)。
青島打井鉆井降水的基本要求
1、當(dang)地(di)下(xia)水(shui)位高于基坑(keng)(keng)開(kai)(kai)(kai)挖面(mian)，需要采(cai)用(yong)降低地(di)下(xia)水(shui)方法(fa)疏(shu)干(gan)坑(keng)(keng)內土(tu)(tu)層(ceng)中(zhong)水(shui)。疏(shu)干(gan)水(shui)有增加(jia)坑(keng)(keng)內土(tu)(tu)體強(qiang)度的作(zuo)用(yong)，有利(li)于控制基坑(keng)(keng)圍(wei)護結構變(bian)形。在軟土(tu)(tu)地(di)區基坑(keng)(keng)開(kai)(kai)(kai)挖深度超過3m，一般就要用(yong)井(jing)點(dian)降水(shui)。開(kai)(kai)(kai)挖深度淺時(shi)，亦可邊開(kai)(kai)(kai)挖邊用(yong)排水(shui)溝(gou)和集(ji)水(shui)井(jing)進行(xing)集(ji)水(shui)明排。
2、當基(ji)坑(keng)底(di)為隔水(shui)(shui)(shui)層(ceng)且(qie)層(ceng)底(di)作用(yong)有(you)承(cheng)壓(ya)水(shui)(shui)(shui)時(shi)，應進行坑(keng)底(di)突(tu)涌驗算，必要時(shi)可(ke)采取水(shui)(shui)(shui)平封底(di)隔滲(shen)或鉆孔(kong)減壓(ya)措施(shi)，保證(zheng)坑(keng)底(di)土層(ceng)穩定。當坑(keng)底(di)含承(cheng)壓(ya)水(shui)(shui)(shui)層(ceng)上部土體壓(ya)重(zhong)不足以抵抗承(cheng)壓(ya)水(shui)(shui)(shui)水(shui)(shui)(shui)頭時(shi)，應布置降壓(ya)井降低承(cheng)壓(ya)水(shui)(shui)(shui)水(shui)(shui)(shui)頭壓(ya)力，防(fang)止承(cheng)壓(ya)水(shui)(shui)(shui)突(tu)涌，確保基(ji)坑(keng)開挖施(shi)工安全。
3、當因降水(shui)(shui)而危(wei)及基坑及周邊環境安全(quan)時(shi)，宜采(cai)用截水(shui)(shui)或回灌(guan)方法。
明(ming)渠(qu)加(jia)集(ji)水(shui)坑(keng)降水(shui)具(ju)有(you)施(shi)(shi)工(gong)方便，費用(yong)(yong)(yong)低廉(lian)等(deng)特點，在(zai)(zai)(zai)施(shi)(shi)工(gong)現場應用(yong)(yong)(yong)的(de)(de)z為(wei)普遍(bian)。在(zai)(zai)(zai)高(gao)水(shui)位(wei)地(di)區基坑(keng)邊坡支護(hu)工(gong)程中(zhong)，這(zhe)種(zhong)方法(fa)往往作為(wei)其它(ta)降水(shui)方法(fa)的(de)(de)輔助降排水(shui)措施(shi)(shi)，它(ta)主要排除地(di)下潛水(shui)、施(shi)(shi)工(gong)用(yong)(yong)(yong)水(shui)和天降雨水(shui)。在(zai)(zai)(zai)地(di)下水(shui)蓄(xu)量(liang)較小(xiao)，地(di)質條件(jian)較好的(de)(de)情況下，使(shi)用(yong)(yong)(yong)明(ming)渠(qu)和集(ji)水(shui)井可以(yi)清除基坑(keng)內積水(shui)。但(dan)是(shi)，在(zai)(zai)(zai)地(di)下水(shui)較豐富地(di)區，若(ruo)僅單獨采用(yong)(yong)(yong)這(zhe)種(zhong)方法(fa)降水(shui)，由(you)于基坑(keng)邊坡滲水(shui)較多，作業面泥濘不堪(kan)，有(you)不利于結構物施(shi)(shi)工(gong)。因此，這(zhe)種(zhong)降水(shui)方法(fa)一(yi)般不單獨應用(yong)(yong)(yong)于高(gao)水(shui)位(wei)地(di)區基坑(keng)邊坡支護(hu)中(zhong)，通常會與降水(shui)井點或截滲幕墻配合使(shi)用(yong)(yong)(yong)。