沉管灌(guan)注成樁(zhuang)施(shi)工(gong)(gong)過程中(zhong)應觀測新(xin)施(shi)工(gong)(gong)樁(zhuang)對已施(shi)工(gong)(gong)樁(zhuang)的影響，當發現樁(zhuang)斷裂(lie)并脫開(kai)時，必須對工(gong)(gong)程樁(zhuang)逐樁(zhuang)靜壓(ya)(ya)，靜壓(ya)(ya)時間一般(ban)為3min，靜壓(ya)(ya)荷(he)載以保證使(shi)斷樁(zhuang)接(jie)起來(lai)為準。

復合(he)地(di)基的基坑(keng)可采用(yong)人(ren)(ren)(ren)工(gong)或機械(xie)(xie)、人(ren)(ren)(ren)工(gong)聯合(he)開(kai)挖。機械(xie)(xie)、人(ren)(ren)(ren)工(gong)聯合(he)開(kai)挖時，予(yu)留人(ren)(ren)(ren)工(gong)開(kai)挖厚度應由現場開(kai)挖確定，以(yi)保障機械(xie)(xie)開(kai)挖造成樁的斷裂(lie)部(bu)位不(bu)低于基礎底面標(biao)高，且樁間土不(bu)受擾(rao)動。

設備的選型

CFG樁(zhuang)(zhuang)可(ke)選用(yong)振(zhen)動沉管(guan)鉆(zhan)(zhan)機或長(chang)(chang)螺旋鉆(zhan)(zhan)機施工(gong)(gong)。具體(ti)選用(yong)哪(na)一類成(cheng)(cheng)(cheng)樁(zhuang)(zhuang)機械(xie)和什么(me)型(xing)號，要視工(gong)(gong)程的具體(ti)情況而定。對(dui)于粘(zhan)性土(tu)、粉(fen)土(tu)、淤泥(ni)質(zhi)土(tu)采用(yong)振(zhen)動沉管(guan)成(cheng)(cheng)(cheng)樁(zhuang)(zhuang)工(gong)(gong)藝。對(dui)存在的夾有(you)硬土(tu)層地(di)質(zhi)條件的地(di)區，使(shi)用(yong)振(zhen)動沉管(guan)機施工(gong)(gong)，CFG樁(zhuang)(zhuang)報價，會對(dui)已成(cheng)(cheng)(cheng)的樁(zhuang)(zhuang)造成(cheng)(cheng)(cheng)較(jiao)大(da)的振(zhen)動，CFG樁(zhuang)(zhuang)廠家(jia)，導致樁(zhuang)(zhuang)體(ti)被震裂(lie)或震斷。對(dui)于靈(ling)敏度較(jiao)高(gao)的土(tu)，振(zhen)動會造成(cheng)(cheng)(cheng)土(tu)的結構強度破壞(huai)、承載力下降，可(ke)采用(yong)螺旋鉆(zhan)(zhan)預(yu)引孔(kong)，再用(yong)振(zhen)動沉管(guan)成(cheng)(cheng)(cheng)樁(zhuang)(zhuang)工(gong)(gong)藝。對(dui)于成(cheng)(cheng)(cheng)孔(kong)要求質(zhi)量(liang)高(gao)的地(di)區，使(shi)用(yong)長(chang)(chang)螺旋鉆(zhan)(zhan)孔(kong)管(guan)內泵壓成(cheng)(cheng)(cheng)樁(zhuang)(zhuang)工(gong)(gong)藝。本(ben)標段設計采用(yong)長(chang)(chang)螺旋鉆(zhan)(zhan)機施工(gong)(gong)。

灌注混凝土

長螺旋鉆(zhan)(zhan)(zhan)(zhan)機(ji)(ji)鉆(zhan)(zhan)(zhan)(zhan)至(zhi)設計標(biao)高，停止(zhi)鉆(zhan)(zhan)(zhan)(zhan)進(jin)，向(xiang)鉆(zhan)(zhan)(zhan)(zhan)桿芯(xin)管(guan)泵(beng)(beng)(beng)送(song)(song)(song)(song)混(hun)(hun)凝土(tu)灌(guan)注(zhu)，當鉆(zhan)(zhan)(zhan)(zhan)桿芯(xin)管(guan)中充滿混(hun)(hun)合(he)(he)料，開(kai)始提升(sheng)鉆(zhan)(zhan)(zhan)(zhan)桿，壓灌(guan)混(hun)(hun)合(he)(he)料，一邊拔(ba)管(guan)，一邊泵(beng)(beng)(beng)送(song)(song)(song)(song)，嚴禁先提管(guan)后泵(beng)(beng)(beng)料。混(hun)(hun)凝土(tu)坍落度(du)、拌合(he)(he)時(shi)間應(ying)按(an)工藝性試驗確(que)定(ding)的(de)參數(shu)進(jin)行控制，攪(jiao)拌時(shi)間不(bu)得少(shao)于1min。泵(beng)(beng)(beng)送(song)(song)(song)(song)混(hun)(hun)凝土(tu)，嚴禁先拔(ba)管(guan)后泵(beng)(beng)(beng)送(song)(song)(song)(song)混(hun)(hun)凝土(tu)（特別是端承樁(zhuang)(zhuang)），拔(ba)管(guan)時(shi)鉆(zhan)(zhan)(zhan)(zhan)桿必須停止(zhi)轉動，CFG樁(zhuang)(zhuang)工程施工，拔(ba)管(guan)速(su)(su)率應(ying)按(an)試樁(zhuang)(zhuang)確(que)定(ding)參數(shu)進(jin)行控制，拔(ba)管(guan)速(su)(su)度(du)均勻，穿透地(di)質較硬地(di)段，采用低(di)檔慢速(su)(su)鉆(zhan)(zhan)(zhan)(zhan)進(jin)，軟弱地(di)層(ceng)，快速(su)(su)鉆(zhan)(zhan)(zhan)(zhan)進(jin)，以(yi)降低(di)擴孔系數(shu)；混(hun)(hun)凝土(tu)泵(beng)(beng)(beng)送(song)(song)(song)(song)也必須連續。若混(hun)(hun)凝土(tu)供應(ying)不(bu)及時(shi)，宜都CFG樁(zhuang)(zhuang)，造(zao)成(cheng)鉆(zhan)(zhan)(zhan)(zhan)機(ji)(ji)等料的(de)情況，時(shi)間較長可能造(zao)成(cheng)斷樁(zhuang)(zhuang)或抱(bao)鉆(zhan)(zhan)(zhan)(zhan)現象，尤其是在飽和砂土(tu)、粉土(tu)層(ceng)。混(hun)(hun)凝土(tu)應(ying)灌(guan)注(zhu)至(zhi)設計CFG樁(zhuang)(zhuang)頂標(biao)高以(yi)上50cm，停止(zhi)泵(beng)(beng)(beng)送(song)(song)(song)(song)混(hun)(hun)凝土(tu)。灌(guan)注(zhu)混(hun)(hun)凝土(tu)方量不(bu)得少(shao)于設計樁(zhuang)(zhuang)長加超灌(guan)樁(zhuang)(zhuang)頭的(de)體積(ji)。