施工技術在地鐵車站施工中的運用
時間:2022-12-01 17:51:47
導語:施工(gong)技術在地鐵車站(zhan)施工(gong)中的運用一文來源(yuan)于(yu)網友上傳,不代表本站(zhan)觀點,若需要原創文章可(ke)咨詢客服(fu)老師(shi),歡迎參(can)考。
摘要:地鐵車(che)(che)站建設中,隧道(dao)跨度越(yue)大,結(jie)構穩(wen)定性越(yue)差(cha),為保證(zheng)現(xian)場施(shi)工安全和工程(cheng)結(jie)構安全,必須(xu)采取(qu)相應(ying)的支(zhi)護措施(shi)。以(yi)某地鐵車(che)(che)站工程(cheng)為例,分別介(jie)紹(shao)了車(che)(che)站暗挖段的超前支(zhi)護、導洞開(kai)挖、主體結(jie)構混(hun)凝土(tu)澆(jiao)筑與(yu)防水處理等環節施(shi)工要點。在施(shi)工期間,對車(che)(che)站工程(cheng)周邊(bian)的地面沉(chen)降(jiang)(jiang)和地下管線(xian)沉(chen)降(jiang)(jiang)進行了觀測(ce)。結(jie)果表明,地面沉(chen)降(jiang)(jiang)速率(lv)和地下管線(xian)沉(chen)降(jiang)(jiang)量均在允許(xu)范圍之內,確保了該工程(cheng)順(shun)利交付驗收。
關鍵詞:超前(qian)支護(hu);暗挖法;ECB防水板;沉降觀(guan)測(ce)
在工(gong)(gong)(gong)(gong)程技術日益(yi)成熟和市民出行需求不斷(duan)增加的影響(xiang)下,現(xian)代地鐵(tie)車(che)站的規模越(yue)來越(yue)大(da)。暗挖法具有挖土(tu)量少、占地面積少、對周邊設(she)施(shi)影響(xiang)小等(deng)一系列特點,是現(xian)階段地鐵(tie)車(che)站施(shi)工(gong)(gong)(gong)(gong)中常用的技術形(xing)式。對于(yu)淺埋大(da)跨(kua)(kua)度(du)車(che)站工(gong)(gong)(gong)(gong)程,現(xian)場暗挖施(shi)工(gong)(gong)(gong)(gong)必須要采取科學的大(da)跨(kua)(kua)度(du)隧洞的支護方案(an)。其(qi)中,主體小導洞開挖支護、主體結構鋼筋(jin)綁扎與混(hun)凝土(tu)澆筑(zhu)等(deng),都是現(xian)場施(shi)工(gong)(gong)(gong)(gong)管理的要點。只(zhi)有落(luo)實(shi)精細化管理,保(bao)(bao)證各個(ge)環(huan)節的施(shi)工(gong)(gong)(gong)(gong)質量都能達到標準,才能確(que)保(bao)(bao)地鐵(tie)車(che)站工(gong)(gong)(gong)(gong)程順利通過驗收。
1工程概況
某市地鐵2號線一期(qi)工(gong)(gong)(gong)程(cheng)車站(zhan)全長(chang)(chang)215.9m,車站(zhan)暗(an)挖(wa)(wa)(wa)段(duan)(duan)為(wei)地下(xia)(xia)兩層(ceng)結構,長(chang)(chang)度(du)72.0m。根(gen)據地質勘測結果,暗(an)挖(wa)(wa)(wa)段(duan)(duan)拱頂(ding)覆(fu)土(tu)厚度(du)在8.3~10.1m,大跨淺埋(mai)暗(an)挖(wa)(wa)(wa)增加了施(shi)(shi)工(gong)(gong)(gong)難度(du)。土(tu)層(ceng)自上(shang)而下(xia)(xia)分別(bie)有(you)雜(za)填土(tu)、粉質黏(nian)土(tu)、細砂、中砂、礫石等,土(tu)層(ceng)穩定性稍(shao)差。同時,車站(zhan)上(shang)方(fang)為(wei)城(cheng)市主干道,車流量密集,動靜(jing)荷載較大。為(wei)節約(yue)工(gong)(gong)(gong)期(qi),該工(gong)(gong)(gong)程(cheng)采用東西側(ce)交替施(shi)(shi)工(gong)(gong)(gong)的方(fang)法(fa),東側(ce)明挖(wa)(wa)(wa)段(duan)(duan)主體結構頂(ding)板施(shi)(shi)工(gong)(gong)(gong)完畢后(hou)(hou)開(kai)(kai)始進(jin)入暗(an)挖(wa)(wa)(wa),做(zuo)(zuo)40m長(chang)(chang)的超前(qian)(qian)支護段(duan)(duan),沿著暗(an)挖(wa)(wa)(wa)段(duan)(duan)上(shang)、下(xia)(xia)導洞(dong)開(kai)(kai)挖(wa)(wa)(wa)30m后(hou)(hou)到達掌子(zi)面(mian),然后(hou)(hou)封閉,開(kai)(kai)始進(jin)行西側(ce)施(shi)(shi)工(gong)(gong)(gong)。西側(ce)明挖(wa)(wa)(wa)段(duan)(duan)做(zuo)(zuo)同樣(yang)處理(li),做(zuo)(zuo)32m長(chang)(chang)的超前(qian)(qian)支護后(hou)(hou),暗(an)挖(wa)(wa)(wa)段(duan)(duan)上(shang)、下(xia)(xia)導洞(dong)開(kai)(kai)挖(wa)(wa)(wa),直到東西側(ce)貫(guan)通。
2車站暗挖段施工技術
超前支護(hu)(hu)采用(yong)(yong)(yong)(yong)“雙層大管(guan)棚+小導(dao)(dao)(dao)(dao)(dao)管(guan)超前注(zhu)漿”的(de)(de)(de)支護(hu)(hu)形式,漿液材(cai)料為(wei)(wei)水:水泥=1:1的(de)(de)(de)水泥漿。其中,大管(guan)棚材(cai)料使(shi)(shi)用(yong)(yong)(yong)(yong)的(de)(de)(de)是φ110mm的(de)(de)(de)熱軋無縫鋼管(guan),小導(dao)(dao)(dao)(dao)(dao)管(guan)材(cai)料使(shi)(shi)用(yong)(yong)(yong)(yong)的(de)(de)(de)是φ45mm的(de)(de)(de)水煤(mei)氣花管(guan)[1]。導(dao)(dao)(dao)(dao)(dao)洞開挖(wa)后(hou),進行初(chu)期支護(hu)(hu)。導(dao)(dao)(dao)(dao)(dao)洞頂部和兩側墻壁的(de)(de)(de)初(chu)期支護(hu)(hu)均采用(yong)(yong)(yong)(yong)“鋼筋(jin)格(ge)柵(zha)+混凝(ning)(ning)(ning)(ning)土(tu)”的(de)(de)(de)形式。導(dao)(dao)(dao)(dao)(dao)洞頂板、墻壁清理干(gan)凈后(hou),使(shi)(shi)用(yong)(yong)(yong)(yong)鋼釘(ding)將鋼筋(jin)格(ge)柵(zha)固定在頂板、墻壁的(de)(de)(de)表面(mian)。現場配制C25混凝(ning)(ning)(ning)(ning)土(tu),使(shi)(shi)用(yong)(yong)(yong)(yong)專(zhuan)用(yong)(yong)(yong)(yong)設備噴射(she)混凝(ning)(ning)(ning)(ning)土(tu)形成(cheng)鋼筋(jin)混凝(ning)(ning)(ning)(ning)土(tu)支護(hu)(hu)結構。噴射(she)混凝(ning)(ning)(ning)(ning)土(tu)的(de)(de)(de)平均厚度(du)為(wei)(wei)240mm。導(dao)(dao)(dao)(dao)(dao)洞內鋼筋(jin)格(ge)柵(zha)的(de)(de)(de)間隔距離為(wei)(wei)80cm。暗(an)挖(wa)段邊樁圍護(hu)(hu)樁使(shi)(shi)用(yong)(yong)(yong)(yong)機械鉆(zhan)孔樁,單樁長度(du)為(wei)(wei)20m,相鄰兩個樁的(de)(de)(de)距離為(wei)(wei)2.5m,并采用(yong)(yong)(yong)(yong)掛(gua)網方式連接。樁間掛(gua)網選用(yong)(yong)(yong)(yong)鋼筋(jin)網,噴射(she)C25混凝(ning)(ning)(ning)(ning)土(tu)。
3主體導洞開挖支護技術
3.1導(dao)洞開(kai)挖(wa)支護
在(zai)導(dao)(dao)洞(dong)(dong)開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)支(zhi)護施工中,采用“臺階(jie)(jie)法(fa)”開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)導(dao)(dao)洞(dong)(dong),見圖1。臺階(jie)(jie)長度為4.8m,每階(jie)(jie)高度為50cm。按(an)照(zhao)自(zi)上而下的順序依次開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)臺階(jie)(jie),上導(dao)(dao)洞(dong)(dong)臺階(jie)(jie)開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)結(jie)束(shu)(shu)后(hou)(hou),保(bao)留(liu)核(he)心土;然(ran)(ran)后(hou)(hou)參(can)照(zhao)格(ge)(ge)柵(zha)間(jian)距繼(ji)續開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)第(di)二、第(di)三(san)層臺階(jie)(jie)。所有臺階(jie)(jie)開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)完(wan)(wan)畢后(hou)(hou),清理泥土,噴射混(hun)凝土,封(feng)閉(bi)掌子(zi)面(mian)(mian)。等到(dao)(dao)(dao)初噴混(hun)凝土完(wan)(wan)全硬結(jie)后(hou)(hou),在(zai)架(jia)設格(ge)(ge)柵(zha)鋼架(jia),將(jiang)鋼筋網片固(gu)定(ding)到(dao)(dao)(dao)格(ge)(ge)柵(zha)鋼架(jia)內,并使用鐵絲(si)將(jiang)兩(liang)者綁扎(zha)、固(gu)定(ding)。最后(hou)(hou)選(xuan)擇C25混(hun)凝土進行復噴,保(bao)證(zheng)平均(jun)厚度達到(dao)(dao)(dao)250mm。等到(dao)(dao)(dao)復噴混(hun)凝土完(wan)(wan)全硬結(jie)后(hou)(hou),即可完(wan)(wan)成導(dao)(dao)洞(dong)(dong)斷面(mian)(mian)支(zhi)護。導(dao)(dao)洞(dong)(dong)開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)支(zhi)護時,還(huan)應關注(zhu)以(yi)下技術(shu)要(yao)點(dian):(1)按(an)照(zhao)“快(kuai)封(feng)閉(bi)”原則,每階(jie)(jie)臺階(jie)(jie)開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)結(jie)束(shu)(shu)后(hou)(hou)快(kuai)速(su)完(wan)(wan)成掛網、噴射混(hun)凝土的封(feng)閉(bi)處(chu)理,可以(yi)降低對周(zhou)邊環(huan)境的不良(liang)影響(xiang),保(bao)證(zheng)結(jie)構穩定(ding);(2)上臺階(jie)(jie)施工期間(jian),在(zai)鎖腳錨管(guan)與(yu)鋼筋格(ge)(ge)柵(zha)焊(han)接完(wan)(wan)成后(hou)(hou),需要(yao)在(zai)格(ge)(ge)柵(zha)下方墊上一塊600mm×300mm×20mm的木板,擴大承壓面(mian)(mian),防止格(ge)(ge)柵(zha)在(zai)上部荷載作(zuo)用下嵌入土體(ti)而發生結(jie)構變(bian)形(xing);(3)雙向開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)小(xiao)導(dao)(dao)洞(dong)(dong)時,如果掌子(zi)面(mian)(mian)凈(jing)距離不足5m,則暫停一側(ce)掌子(zi)面(mian)(mian)的開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa),并通過掛網噴射混(hun)凝土的方式封(feng)閉(bi)該掌子(zi)面(mian)(mian),然(ran)(ran)后(hou)(hou)繼(ji)續從(cong)另一側(ce)開(kai)(kai)(kai)(kai)(kai)(kai)挖(wa)(wa)剩(sheng)余土體(ti)。
3.2拱頂(ding)初(chu)支扣(kou)拱
本(ben)次(ci)工程中(zhong)的(de)拱(gong)(gong)頂(ding)(ding)初支扣拱(gong)(gong)分(fen)為(wei)兩(liang)(liang)部分(fen),即邊導(dao)(dao)洞(dong)內扣拱(gong)(gong)和導(dao)(dao)洞(dong)間(jian)扣拱(gong)(gong),導(dao)(dao)洞(dong)洞(dong)內扣拱(gong)(gong)見圖2。在進行車站(zhan)主體邊樁頂(ding)(ding)冠梁施(shi)工時,可同步(bu)開(kai)展(zhan)邊導(dao)(dao)洞(dong)的(de)內扣拱(gong)(gong)作(zuo)業。在導(dao)(dao)洞(dong)內扣拱(gong)(gong)施(shi)工時,格柵的(de)一(yi)個(ge)端頭要使(shi)(shi)用(yong)螺栓固(gu)定(ding)到導(dao)(dao)洞(dong)的(de)拱(gong)(gong)頂(ding)(ding)上,另一(yi)個(ge)端頭則使(shi)(shi)用(yong)U型筋(jin)與預埋鋼(gang)板焊接固(gu)定(ding)。導(dao)(dao)洞(dong)格柵就位后,即表示扣拱(gong)(gong)成功。導(dao)(dao)洞(dong)間(jian)扣拱(gong)(gong)則按照“由外向內”的(de)順序開(kai)展(zhan),并且施(shi)工進度需要與車站(zhan)拱(gong)(gong)頂(ding)(ding)土(tu)方(fang)開(kai)挖保持一(yi)致。導(dao)(dao)洞(dong)扣拱(gong)(gong)施(shi)工結束后,開(kai)展(zhan)封(feng)底(di)格柵作(zuo)業。本(ben)次(ci)工程中(zhong)使(shi)(shi)用(yong)的(de)封(feng)底(di)格柵為(wei)20a工字鋼(gang),沿著(zhu)車站(zhan)方(fang)向東(dong)西布置(zhi),封(feng)底(di)格柵的(de)間(jian)隔距離為(wei)60cm,相(xiang)鄰兩(liang)(liang)塊封(feng)底(di)格柵使(shi)(shi)用(yong)連接筋(jin)(雙層22號鋼(gang)筋(jin))焊接固(gu)定(ding)。格柵間(jian)掛雙層鋼(gang)筋(jin)網,使(shi)(shi)用(yong)C25混(hun)凝(ning)土(tu)噴射完成封(feng)底(di)。3.3導(dao)(dao)洞(dong)主體部分(fen)施(shi)工技術
3.3.1模板的安裝
底(di)板(ban)(ban)(ban)倒(dao)角模(mo)(mo)板(ban)(ban)(ban)采用(yong)的是單塊長度為(wei)1.2m的定(ding)型鋼(gang)模(mo)(mo)板(ban)(ban)(ban),固定(ding)在(zai)底(di)板(ban)(ban)(ban)鋼(gang)筋上。樁頂冠梁模(mo)(mo)板(ban)(ban)(ban)使用(yong)的是高度為(wei)1.2m、厚度為(wei)15mm的竹膠板(ban)(ban)(ban),模(mo)(mo)板(ban)(ban)(ban)外(wai)(wai)側(ce)(ce)(ce)(ce)使用(yong)斜支(zhi)撐。底(di)部縱梁模(mo)(mo)板(ban)(ban)(ban)同樣采用(yong)15mm厚的竹膠板(ban)(ban)(ban),使用(yong)U型托和小導洞(dong)初(chu)支(zhi)側(ce)(ce)(ce)(ce)墻(qiang)支(zhi)撐模(mo)(mo)板(ban)(ban)(ban)[2]。模(mo)(mo)板(ban)(ban)(ban)工(gong)程的安裝流程如(ru)下:在(zai)鋼(gang)筋綁扎并驗收通過后(hou),在(zai)施工(gong)現場(chang)彈出(chu)墻(qiang)邊線。首先安裝外(wai)(wai)墻(qiang)模(mo)(mo)板(ban)(ban)(ban),然后(hou)采用(yong)吊裝方式將單側(ce)(ce)(ce)(ce)支(zhi)架吊升到(dao)作業面,現場(chang)完成模(mo)(mo)板(ban)(ban)(ban)單側(ce)(ce)(ce)(ce)支(zhi)架的安裝。單側(ce)(ce)(ce)(ce)支(zhi)架的間(jian)隔距(ju)離為(wei)1200mm,支(zhi)架中(zhong)間(jian)處(chu)使用(yong)φ50mm加強鋼(gang)管進行(xing)固定(ding)。
3.3.2鋼筋(jin)的綁扎
鋼筋(jin)(jin)進(jin)場(chang)后(hou)需(xu)要仔細核對(dui)型號、尺寸(cun)、數量(liang)(liang)等是否(fou)符合要求,同時檢查外(wai)觀質(zhi)量(liang)(liang),對(dui)于(yu)輕微彎(wan)曲、生(sheng)銹的(de)(de),要進(jin)行(xing)調(diao)直、除銹;對(dui)于(yu)存在(zai)嚴重質(zhi)量(liang)(liang)缺陷的(de)(de)不得使用(yong)。本次(ci)工(gong)程中基(ji)礎梁(liang)(liang)(liang)的(de)(de)形式(shi)為下翻梁(liang)(liang)(liang),現(xian)場(chang)綁扎梁(liang)(liang)(liang)鋼筋(jin)(jin)時,需(xu)要先(xian)在(zai)基(ji)礎梁(liang)(liang)(liang)的(de)(de)上口架設5根橫(heng)桿,并焊接(jie)(jie)固定(ding)。然后(hou)等間(jian)距(50cm)插入箍筋(jin)(jin),再穿(chuan)入基(ji)礎梁(liang)(liang)(liang)的(de)(de)下部(bu)縱筋(jin)(jin)和構造鋼筋(jin)(jin)。底板主筋(jin)(jin)從梁(liang)(liang)(liang)的(de)(de)上部(bu)縱筋(jin)(jin)和構造鋼筋(jin)(jin)之間(jian)穿(chuan)過,同樣采用(yong)焊接(jie)(jie)方式(shi)固定(ding)。鋼筋(jin)(jin)安(an)裝(zhuang)完畢后(hou),測量(liang)(liang)位置(zhi)偏差(cha)和焊接(jie)(jie)質(zhi)量(liang)(liang),保(bao)證實際(ji)偏差(cha)控制在(zai)允許范圍,并且(qie)焊接(jie)(jie)牢固后(hou),方可(ke)繼續(xu)下一步施工(gong)。
3.3.3混凝土澆筑
該(gai)工程主體結構采用(yong)(yong)混(hun)(hun)凝(ning)土(tu)(tu)澆(jiao)(jiao)筑(zhu)(zhu)(zhu)而成,不同(tong)位置的施工方(fang)法和澆(jiao)(jiao)筑(zhu)(zhu)(zhu)順序存在差異(yi)。頂、底板按照由邊墻(qiang)向中線的順序連續澆(jiao)(jiao)筑(zhu)(zhu)(zhu);側墻(qiang)采用(yong)(yong)泵車分層連續澆(jiao)(jiao)筑(zhu)(zhu)(zhu)。澆(jiao)(jiao)筑(zhu)(zhu)(zhu)作業(ye)中,要(yao)(yao)求混(hun)(hun)凝(ning)土(tu)(tu)的自由下(xia)落(luo)高度(du)≤2.5m,如果超過該(gai)高度(du)需要(yao)(yao)使用(yong)(yong)溜(liu)槽或串桶(tong),避免出現混(hun)(hun)凝(ning)土(tu)(tu)離析情況。在分層澆(jiao)(jiao)筑(zhu)(zhu)(zhu)時,中間(jian)的間(jian)隔時間(jian)要(yao)(yao)盡可能的短,要(yao)(yao)求上(shang)一(yi)層混(hun)(hun)凝(ning)土(tu)(tu)完成初凝(ning)后(hou)(hou)立即開始下(xia)一(yi)層的澆(jiao)(jiao)筑(zhu)(zhu)(zhu)[3]。混(hun)(hun)凝(ning)土(tu)(tu)振(zhen)搗(dao)(dao)作業(ye)時應保(bao)證(zheng)表(biao)(biao)面返漿(jiang)為止,避免出現蜂(feng)窩、麻面的現象。現場澆(jiao)(jiao)筑(zhu)(zhu)(zhu)時還應安排(pai)專人負責(ze)檢(jian)查模板接縫處、預留孔洞處有無漏漿(jiang)情況,如果有要(yao)(yao)及(ji)時匯報(bao)、處理。振(zhen)搗(dao)(dao)完畢后(hou)(hou),用(yong)(yong)刮(gua)尺刮(gua)平表(biao)(biao)面,等到表(biao)(biao)面收水后(hou)(hou)再用(yong)(yong)木抹(mo)子壓實,之后(hou)(hou)進入養護工序。本次工程中采用(yong)(yong)濕(shi)麻袋覆蓋養護,定(ding)期灑水,避免混(hun)(hun)凝(ning)土(tu)(tu)干裂(lie)。
3.4導洞防水(shui)施工(gong)技術
導洞防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)工(gong)程主(zhu)要(yao)用(yong)(yong)材(cai)為(wei)(wei)2.0mm厚的ECB塑(su)料外貼(tie)式(shi)防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)板,具體施工(gong)流程如(ru)下:(1)基(ji)(ji)層部(bu)(bu)分(fen)。通過水(shui)(shui)(shui)泥(ni)砂(sha)(sha)漿抹面(mian)的方式(shi)使(shi)(shi)基(ji)(ji)面(mian)平整。水(shui)(shui)(shui)泥(ni)砂(sha)(sha)漿由水(shui)(shui)(shui)和水(shui)(shui)(shui)泥(ni)按照(zhao)1:2.5的比(bi)例(li)制備(bei)。抹面(mian)時如(ru)果發現(xian)基(ji)(ji)面(mian)上(shang)有(you)凸起(qi)的石塊(kuai),應使(shi)(shi)用(yong)(yong)釬(han)子鑿出(chu)后重新抹平,防(fang)(fang)(fang)(fang)止基(ji)(ji)面(mian)堅硬凸起(qi)物刺破防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)板[4]。(2)緩(huan)沖層部(bu)(bu)分(fen)。緩(huan)沖層的主(zhu)體材(cai)料為(wei)(wei)440g/m2的短纖(xian)無(wu)紡(fang)(fang)布(bu),使(shi)(shi)用(yong)(yong)膨脹(zhang)螺絲將該材(cai)料固(gu)定(ding)到基(ji)(ji)面(mian)上(shang),頂拱上(shang)膨脹(zhang)螺栓的間距為(wei)(wei)60cm,側墻(qiang)上(shang)膨脹(zhang)螺絲的間距為(wei)(wei)100cm。相(xiang)鄰兩塊(kuai)無(wu)紡(fang)(fang)布(bu)采用(yong)(yong)搭接(jie)(jie)(jie)處理,要(yao)求搭接(jie)(jie)(jie)寬度不(bu)得(de)小于5cm。搭接(jie)(jie)(jie)部(bu)(bu)分(fen)的縫隙要(yao)使(shi)(shi)用(yong)(yong)防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)膠進(jin)行(xing)處理。(3)防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)板部(bu)(bu)分(fen)。使(shi)(shi)用(yong)(yong)熱(re)風焊(han)槍(qiang)將防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)板固(gu)定(ding)到預埋的塑(su)料墊片上(shang),焊(han)接(jie)(jie)(jie)結束約10min后,人工(gong)檢查焊(han)接(jie)(jie)(jie)是(shi)否牢固(gu),如(ru)果有(you)局(ju)部(bu)(bu)松動的要(yao)進(jin)行(xing)復焊(han),防(fang)(fang)(fang)(fang)止在澆筑混凝(ning)土時出(chu)現(xian)防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)板脫落的情況。防(fang)(fang)(fang)(fang)水(shui)(shui)(shui)板與基(ji)(ji)面(mian)、緩(huan)沖層無(wu)紡(fang)(fang)布(bu)必(bi)須緊密貼(tie)合,不(bu)得(de)有(you)翹(qiao)邊、空鼓(gu)的情況[5]。
4地鐵車站的監控量測
4.1監測對象(xiang)與(yu)監測點布置
由于該工程周邊有密(mi)集的建(構)筑(zhu)(zhu)物,地(di)(di)下有多條(tiao)市政管(guan)線,因此為保證工程施(shi)工安全和建筑(zhu)(zhu)物、地(di)(di)下管(guan)線的正常使用,必須要采取監(jian)控量測措(cuo)施(shi)[6]。監(jian)測內容(rong)為地(di)(di)表沉降和地(di)(di)下管(guan)線情(qing)況。監(jian)測點布(bu)置見(jian)圖3。
4.2監測標準
地鐵車站(zhan)工(gong)(gong)程周邊道路(lu)及地面的最大(da)(da)沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)速率≤4mm/d;市政(zheng)管(guan)線(xian)的沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)控制標準(zhun)見(jian)表1。4.3監測(ce)結果(guo)地面沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)與地下(xia)管(guan)線(xian)沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)結果(guo)見(jian)圖(tu)4、圖(tu)5。結合(he)圖(tu)4、圖(tu)5可以發(fa)現(xian),在(zai)本次工(gong)(gong)程的暗挖段施工(gong)(gong)中,6個(ge)監測(ce)點中最大(da)(da)沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)出現(xian)在(zai)DBA02-1監測(ce)點,整個(ge)監測(ce)周期內累計沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)量(liang)為(wei)68.4mm,則最大(da)(da)位移速率為(wei)68.4/365=0.19mm/d<3mm/d,滿足要求。地下(xia)管(guan)線(xian)的沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)監測(ce)中,GXC04-13監測(ce)點有最大(da)(da)沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang),整個(ge)檢測(ce)周期內累計沉(chen)(chen)(chen)(chen)降(jiang)(jiang)(jiang)量(liang)為(wei)9.1mm<10mm,也(ye)滿足要求。
5結論
在淺埋大跨度地鐵車站的暗挖施工中,超前支護、導洞開挖和主體結構的鋼筋工程、混凝土工程是施工管理的重點。在本次工程中,通過落實精細化管理,保證了工程施工的順利進行。考慮到該工程所在地區建(構)筑(zhu)物密集,地(di)下管網交錯分(fen)布(bu),因此在(zai)施(shi)工期間同步開展了地(di)面沉降(jiang)觀(guan)測(ce)和(he)地(di)下管線(xian)沉降(jiang)觀(guan)測(ce)。監測(ce)結果(guo)表明,地(di)面沉降(jiang)速(su)率和(he)地(di)下管線(xian)最大沉降(jiang)量均(jun)在(zai)要求范圍(wei)之內(nei),間接說(shuo)明了暗(an)挖法施(shi)工在(zai)占地(di)面積(ji)小(xiao)、對周(zhou)圍(wei)設(she)施(shi)影(ying)響小(xiao)等(deng)方面具有顯著優(you)勢。
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作者(zhe):李軻 單位:中電建鐵路建設投資集團有限公司