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哈爾濱深基坑支護工程施工前,更先應依照標準的規定,根據深基坑坑壁毀壞后很有可能導致不良影響的嚴重后果明確深基坑坑壁的級別,隨后依據坑壁安全級別、深基坑周圍環境、基坑開挖深層、水文地質與地質構造、工程施工工作機器設備和工程施工時節的標準等要素挑選坑壁的方式。
推(tui)薦深基(ji)坑(keng)塌陷的(de)防范(fan)措施:
一、挑選合適(shi)的深基坑(keng)坑(keng)壁方式(shi)
樁孔回填當(dang)坑基(ji)頂(ding)端無關鍵建(jian)(構)筑物,場所有坡(po)(po)度標(biao)準(zhun)且深(shen)基(ji)坑深(shen)層≤十(shi)米時(shi),能夠(gou)優先(xian)選(xuan)擇選(xuan)用坡(po)(po)率法(fa)(fa)。選(xuan)用坡(po)(po)率法(fa)(fa)時(shi),關鍵是(shi)要明確恰當(dang)的(de)坡(po)(po)率規(gui)定值。一般坑壁的(de)坡(po)(po)率規(gui)定值可按工程(cheng)項目(mu)對比的(de)標(biao)準(zhun)并融合現有平穩護坡(po)(po)的(de)坡(po)(po)率值剖(pou)析明確。如:土層勻稱優良的(de)硬塑粘性土,當(dang)坡(po)(po)高(gao)低于5m時(shi),坡(po)(po)率規(gui)定值可明確為:1:1.00~1:1.25。若坑壁土層過軟或深(shen)基(ji)坑頂(ding)端邊沿附近(jin)有很大載荷,坡(po)(po)率規(gui)定值還務必選(xuan)用弧形拖動(dong)法(fa)(fa)開(kai)展(zhan)可靠性剖(pou)析明確。
樁孔回填
smw工(gong)法攪(jiao)拌(ban)樁(zhuang)當(dang)工(gong)程施工(gong)場所(suo)不可(ke)以考(kao)慮設(she)計方案坡率值的規定(ding)時,解決坑(keng)壁采用錨(mao)桿支(zhi)護對策。挑選(xuan)(xuan)錨(mao)桿支(zhi)護構造(zao),更(geng)先要(yao)明(ming)確深(shen)基坑(keng)坑(keng)壁的安(an)(an)全級別。依照標(biao)準的規定(ding),坑(keng)壁的安(an)(an)全級別按其毀(hui)壞(huai)后很有可(ke)能導致的毀(hui)壞(huai)不良(liang)影(ying)響的嚴重后果(guo)、坑(keng)壁種類(lei)和深(shen)基坑(keng)深(shen)層(ceng)等要(yao)素,明(ming)確為一、二、三級。坑(keng)壁安(an)(an)全級別一、二級合適選(xuan)(xuan)用成孔鉆孔灌注樁(zhuang)孔樁(zhuang),坑(keng)壁安(an)(an)全級別二、三級合適選(xuan)(xuan)用土釘墻孔樁(zhuang)。
二、提升對基坑開挖的監管
深(shen)基(ji)(ji)(ji)(ji)坑土(tu)方(fang)回填一般選(xuan)用機械(xie)設備(bei)挖(wa)法,基(ji)(ji)(ji)(ji)坑開(kai)(kai)(kai)(kai)挖(wa)前,應依據(ju)深(shen)基(ji)(ji)(ji)(ji)坑坑壁(bi)方(fang)式(shi)、降排水管(guan)道規定等制(zhi)訂基(ji)(ji)(ji)(ji)坑開(kai)(kai)(kai)(kai)挖(wa)計(ji)劃方(fang)案,并對機械(xie)設備(bei)實(shi)際操(cao)作工作人員開(kai)(kai)(kai)(kai)展安全交底(di)。基(ji)(ji)(ji)(ji)坑開(kai)(kai)(kai)(kai)挖(wa)時,需有專(zhuan)業(ye)技術人員到場,對基(ji)(ji)(ji)(ji)坑開(kai)(kai)(kai)(kai)挖(wa)深(shen)層、坑壁(bi)傾(qing)斜(xie)度(du)開(kai)(kai)(kai)(kai)展監管(guan),避免(mian)挖(wa)深(shen)。對選(xuan)用土(tu)釘墻(qiang)支(zhi)護的深(shen)基(ji)(ji)(ji)(ji)坑,基(ji)(ji)(ji)(ji)坑開(kai)(kai)(kai)(kai)挖(wa)深(shen)層應嚴控(kong),不可(ke)在上一段土(tu)釘墻(qiang)孔樁未工程施工結束前基(ji)(ji)(ji)(ji)坑開(kai)(kai)(kai)(kai)挖(wa)下一段土(tu)方(fang)回填。
軟基處理深(shen)(shen)基坑(keng)務必層(ceng)次平衡(heng)基坑(keng)開挖,樓高不適合超出1米。對選用當然坡(po)度的(de)深(shen)(shen)基坑(keng),坑(keng)壁傾斜度是監(jian)管的(de)關(guan)鍵,當出現(xian)深(shen)(shen)基坑(keng)具體深(shen)(shen)層(ceng)超過設計方案深(shen)(shen)層(ceng)時,應立即(ji)調節坑(keng)頂基坑(keng)開挖線,確保坑(keng)壁坡(po)率符合要求。
三(san)、提升對錨桿支(zhi)護(hu)構造施工(gong)質量的監管
不斷完善建(jian)筑企業內部錨(mao)桿(gan)支(zhi)護(hu)構(gou)造(zao)工(gong)(gong)程施工(gong)(gong)產品質量檢驗(yan)規章制度,是(shi)確(que)保(bao)錨(mao)桿(gan)支(zhi)護(hu)構(gou)造(zao)施工(gong)(gong)質量的關鍵方式。產品質量檢驗(yan)的目標包含(han)錨(mao)桿(gan)支(zhi)護(hu)構(gou)造(zao)常(chang)用原材(cai)料(liao)和(he)錨(mao)桿(gan)支(zhi)護(hu)構(gou)造(zao)自身
對(dui)錨桿支(zhi)(zhi)護(hu)構(gou)造原料(liao)及半成品加工(gong)應遵循相關工(gong)程施工(gong)驗(yan)收標(biao)準開展檢測(ce),具(ju)體內容有(you):(1)原材料(liao)產品合格證查驗(yan);(2)原材料(liao)當場抽樣(yang)檢驗(yan);(3)錨索料(liao)漿和混(hun)泥(ni)土(tu)(tu)的(de)砂漿配合比實(shi)驗(yan),抗壓強度級別檢測(ce)。對(dui)錨桿支(zhi)(zhi)護(hu)構(gou)造自身的(de)檢測(ce)要(yao)依(yi)據錨桿支(zhi)(zhi)護(hu)構(gou)造的(de)方(fang)式挑選(xuan),如土(tu)(tu)釘墻(qiang)解(jie)決土(tu)(tu)釘選(xuan)用抗壓強度材料(liao)檢測(ce)承(cheng)載能(neng)力、對(dui)混(hun)泥(ni)土(tu)(tu)注漿應檢驗(yan)樁身一致性等。
四、提(ti)升對地下水(shui)的操縱
在深基坑(keng)(keng)工(gong)(gong)程(cheng)施工(gong)(gong)產(chan)前,應(ying)摸透深基坑(keng)(keng)附近(jin)的管道(dao)網狀況,防(fang)止在工(gong)(gong)程(cheng)施工(gong)(gong)全過程(cheng)中對管道(dao)網導致危害(hai),出現(xian)(xian)爆或漏(lou)水(shui)。另外為(wei)降(jiang)低地下水(shui)滲透到(dao)坑(keng)(keng)壁(bi)砂土,深基坑(keng)(keng)頂端四周運用混泥土封閉(bi)式,施工(gong)(gong)工(gong)(gong)地內要設土層排水(shui)設備,對降(jiang)水(shui)、工(gong)(gong)程(cheng)施工(gong)(gong)自來(lai)水(shui)、從降(jiang)水(shui)井中抽出來(lai)的地表水(shui)等(deng)開展有機構(gou)排污,對坑(keng)(keng)邊的存水(shui)坑(keng)(keng)、降(jiang)雨沉淀池應(ying)做防(fang)水(shui)解決,避免出現(xian)(xian)漏(lou)水(shui)。
對選(xuan)用錨桿(gan)支護構造的(de)坑(keng)(keng)壁應設定(ding)泄水(shui)(shui)孔,確保孔樁里側土(tu)身體水(shui)(shui)壓(ya)力能(neng)立即(ji)清除,降低砂土(tu)含水(shui)(shui)量,也有利(li)于(yu)觀(guan)查(cha)深基坑(keng)(keng)附近土(tu)身體地下水(shui)(shui)的(de)狀況,立即(ji)采取(qu)一定(ding)的(de)有效措施(shi)。泄水(shui)(shui)孔外傾角傾斜度不適合低于(yu)5%,間隔宜(yi)為2~3M,并宜(yi)按梅花形布置。
五(wu)、做好錨桿支(zhi)護構造的當場檢測
錨桿支(zhi)護構造(zao)的(de)檢(jian)(jian)測(ce)(ce)(ce)是避免錨桿支(zhi)護構造(zao)產(chan)生塌陷的(de)關鍵(jian)方(fang)式(shi)。在錨桿支(zhi)護總體(ti)設計時(shi)要明確提出檢(jian)(jian)測(ce)(ce)(ce)規定,由有資質證(zheng)書的(de)檢(jian)(jian)測(ce)(ce)(ce)企業定編(bian)監測(ce)(ce)(ce)方(fang)案(an)(an),經設計方(fang)案(an)(an)、工程監理認同后(hou)執行。監測(ce)(ce)(ce)方(fang)案(an)(an)應(ying)包含檢(jian)(jian)測(ce)(ce)(ce)目地、檢(jian)(jian)測(ce)(ce)(ce)新(xin)項目、測(ce)(ce)(ce)試(shi)標(biao)準、測(ce)(ce)(ce)量點布局、檢(jian)(jian)測(ce)(ce)(ce)周期時(shi)間、檢(jian)(jian)測(ce)(ce)(ce)新(xin)項目警報值、反(fan)饋機(ji)制規章制度和當場初(chu)始情況材料紀(ji)錄等內容。
深基(ji)坑(keng)設計與工程造價的要點分享(xiang)
一、基(ji)坑設計的一般(ban)內(nei)容
支(zhi)護(hu)(hu)體(ti)系的(de)(de)方(fang)案比較和選(xuan)型;支(zhi)護(hu)(hu)結構的(de)(de)強度和變形計算;基(ji)坑內(nei)外土體(ti)的(de)(de)穩(wen)定(ding)性驗(yan)算;維(wei)護(hu)(hu)墻的(de)(de)抗(kang)滲驗(yan)算;降(jiang)水要(yao)求和降(jiang)水方(fang)案;確定(ding)挖(wa)土的(de)(de)工況以(yi)及挖(wa)土、運(yun)土的(de)(de)主要(yao)措(cuo)施;確定(ding)環境保護(hu)(hu)的(de)(de)要(yao)求及有關(guan)措(cuo)施;監測的(de)(de)內(nei)容。
二、進行(xing)基坑工程設計時,應考慮(lv)的荷載(zai)
土壓(ya)力、水(shui)(shui)壓(ya)力;地(di)面超載(zai)(zai);影響(xiang)范圍內建(構)筑物產生的側向荷載(zai)(zai);施(shi)工(gong)荷載(zai)(zai)及鄰近基礎工(gong)程(cheng)施(shi)工(gong)(如打樁、基坑開(kai)挖(wa)、降水(shui)(shui)等)的影響(xiang);需要時,宜結合工(gong)程(cheng)經驗(yan)考慮溫度影響(xiang)和混凝土收縮、徐(xu)變(bian)引起的作用及挖(wa)土和支撐(cheng)施(shi)工(gong)的時空效(xiao)應(ying)。
三、深基坑工程不同(tong)方案計價(jia)分析
深(shen)基(ji)(ji)(ji)坑(keng)(keng)工(gong)(gong)(gong)程(cheng)(cheng)計價(jia)(jia)(jia)(jia)主要(yao)是指深(shen)基(ji)(ji)(ji)坑(keng)(keng)工(gong)(gong)(gong)程(cheng)(cheng)的(de)(de)(de)(de)建筑(zhu)工(gong)(gong)(gong)程(cheng)(cheng)價(jia)(jia)(jia)(jia)格的(de)(de)(de)(de)計算。在(zai)深(shen)基(ji)(ji)(ji)坑(keng)(keng)及(ji)其它地下(xia)工(gong)(gong)(gong)程(cheng)(cheng)施(shi)(shi)工(gong)(gong)(gong)中(zhong),常遇(yu)到深(shen)基(ji)(ji)(ji)坑(keng)(keng)支(zhi)(zhi)護(hu)(hu)(hu)問題(ti),其開挖難度大(da)、工(gong)(gong)(gong)期長、費(fei)用(yong)(yong)高(gao),一(yi)般(ban)占基(ji)(ji)(ji)礎土(tu)(tu)(tu)(tu)建總造(zao)價(jia)(jia)(jia)(jia)的(de)(de)(de)(de)10%-20%,大(da)深(shen)基(ji)(ji)(ji)坑(keng)(keng)工(gong)(gong)(gong)程(cheng)(cheng)的(de)(de)(de)(de)造(zao)價(jia)(jia)(jia)(jia)可達30%-40%,成為城市建設(she)中(zhong)一(yi)個很重要(yao)的(de)(de)(de)(de)研究課題(ti)。深(shen)基(ji)(ji)(ji)坑(keng)(keng)工(gong)(gong)(gong)程(cheng)(cheng)的(de)(de)(de)(de)造(zao)價(jia)(jia)(jia)(jia)包括從(cong)基(ji)(ji)(ji)坑(keng)(keng)圍(wei)護(hu)(hu)(hu)、擋土(tu)(tu)(tu)(tu)、降水(shui)(shui)到土(tu)(tu)(tu)(tu)方(fang)開挖、支(zhi)(zhi)撐(cheng)(cheng)等(deng)(deng)為基(ji)(ji)(ji)礎工(gong)(gong)(gong)程(cheng)(cheng)施(shi)(shi)工(gong)(gong)(gong)服務的(de)(de)(de)(de)所有(you)工(gong)(gong)(gong)程(cheng)(cheng)費(fei)用(yong)(yong)。從(cong)目前基(ji)(ji)(ji)坑(keng)(keng)圍(wei)護(hu)(hu)(hu)設(she)計、施(shi)(shi)工(gong)(gong)(gong)現狀來看(kan),各(ge)(ge)種基(ji)(ji)(ji)坑(keng)(keng)圍(wei)護(hu)(hu)(hu)體(ti)系(xi)的(de)(de)(de)(de)技術性(xing)、安(an)全性(xing)、經濟性(xing)等(deng)(deng)方(fang)面各(ge)(ge)有(you)特點。采用(yong)(yong)疊袋式(shi)(shi)擋墻支(zhi)(zhi)護(hu)(hu)(hu),其費(fei)用(yong)(yong)低、施(shi)(shi)工(gong)(gong)(gong)簡易、進度快,但在(zai)軟土(tu)(tu)(tu)(tu)堆筑(zhu)重力式(shi)(shi)擋土(tu)(tu)(tu)(tu)墻,沉降和水(shui)(shui)平位移較(jiao)大(da),可能(neng)(neng)引起(qi)墻后土(tu)(tu)(tu)(tu)體(ti)坍塌,甚至使地下(xia)室(shi)工(gong)(gong)(gong)程(cheng)(cheng)樁發生(sheng)偏移,引起(qi)周圍(wei)環境的(de)(de)(de)(de)破壞;采用(yong)(yong)重力式(shi)(shi)水(shui)(shui)泥攪拌(ban)樁支(zhi)(zhi)護(hu)(hu)(hu)結構(gou),擋墻厚度大(da)、整體(ti)性(xing)和穩定性(xing)好、隔水(shui)(shui)性(xing)能(neng)(neng)好、施(shi)(shi)工(gong)(gong)(gong)速度快、便于機械挖土(tu)(tu)(tu)(tu),工(gong)(gong)(gong)程(cheng)(cheng)造(zao)價(jia)(jia)(jia)(jia)低于鉆孔(kong)灌注樁加支(zhi)(zhi)撐(cheng)(cheng)的(de)(de)(de)(de)支(zhi)(zhi)護(hu)(hu)(hu)結構(gou),但其水(shui)(shui)平位移也(ye)較(jiao)大(da);采用(yong)(yong)以鉆孔(kong)灌注樁為主的(de)(de)(de)(de)懸臂式(shi)(shi)排樁支(zhi)(zhi)護(hu)(hu)(hu),其優點是其基(ji)(ji)(ji)坑(keng)(keng)內(nei)無支(zhi)(zhi)撐(cheng)(cheng),便于機械挖土(tu)(tu)(tu)(tu)和地下(xia)室(shi)施(shi)(shi)工(gong)(gong)(gong),缺點是支(zhi)(zhi)護(hu)(hu)(hu)變形難控制,一(yi)般(ban)適用(yong)(yong)于較(jiao)淺的(de)(de)(de)(de)基(ji)(ji)(ji)坑(keng)(keng),工(gong)(gong)(gong)程(cheng)(cheng)造(zao)價(jia)(jia)(jia)(jia)也(ye)較(jiao)高(gao);采用(yong)(yong)地下(xia)連(lian)續墻作(zuo)基(ji)(ji)(ji)坑(keng)(keng)圍(wei)護(hu)(hu)(hu),基(ji)(ji)(ji)坑(keng)(keng)穩定性(xing)好、變形和位移小(xiao),但造(zao)價(jia)(jia)(jia)(jia)高(gao)于排樁支(zhi)(zhi)護(hu)(hu)(hu)體(ti)系(xi);采用(yong)(yong)排樁加支(zhi)(zhi)撐(cheng)(cheng)或水(shui)(shui)平拱圈支(zhi)(zhi)撐(cheng)(cheng)體(ti)系(xi),其優點是支(zhi)(zhi)護(hu)(hu)(hu)系(xi)統較(jiao)安(an)全可靠,內(nei)支(zhi)(zhi)撐(cheng)(cheng)布置合理,也(ye)可方(fang)便基(ji)(ji)(ji)坑(keng)(keng)挖土(tu)(tu)(tu)(tu)和地下(xia)室(shi)施(shi)(shi)工(gong)(gong)(gong),其造(zao)價(jia)(jia)(jia)(jia)與(yu)選擇合理的(de)(de)(de)(de)樁型(xing)、樁長及(ji)合適的(de)(de)(de)(de)支(zhi)(zhi)撐(cheng)(cheng)材(cai)料有(you)密切的(de)(de)(de)(de)關系(xi);針對基(ji)(ji)(ji)坑(keng)(keng)內(nei)不同的(de)(de)(de)(de)挖土(tu)(tu)(tu)(tu)深(shen)度采用(yong)(yong)的(de)(de)(de)(de)組(zu)合型(xing)支(zhi)(zhi)護(hu)(hu)(hu),可充(chong)分利用(yong)(yong)圍(wei)護(hu)(hu)(hu)支(zhi)(zhi)撐(cheng)(cheng)的(de)(de)(de)(de)承載(zai)能(neng)(neng)力,采用(yong)(yong)合理支(zhi)(zhi)護(hu)(hu)(hu)體(ti)系(xi),降低基(ji)(ji)(ji)坑(keng)(keng)工(gong)(gong)(gong)程(cheng)(cheng)造(zao)價(jia)(jia)(jia)(jia)。