【正文】 從受力分析看，仰拱與側(cè)墻連接處受影響最大，確保了初期支護(hù)承受足量荷載；其次是加強(qiáng)對(duì)中夾巖柱體的注漿加固，對(duì)其采用對(duì)拉錨桿、加強(qiáng)錨桿和注漿加固 ,確保了圍巖的穩(wěn)定。本工程為今后類(lèi)似的地下鐵道建設(shè)取得了成功的經(jīng)驗(yàn)和應(yīng)用實(shí)例。 輔助剪刀撐加強(qiáng)支護(hù) 通過(guò) ANSYS 模擬分析，為確保小斷面隧道施工安全，必須對(duì)小斷面隧道進(jìn)行輔助支撐加固，抵御爆破產(chǎn)生的瞬時(shí)沖擊和巖層開(kāi)挖時(shí)荷載釋放產(chǎn)生的偏壓。 微差微震爆破技 術(shù) 隧道開(kāi)挖全部采用鉆爆法施工。 5 施工關(guān)鍵技術(shù)及對(duì)應(yīng)措施 連拱隧道段的施工是需要在嚴(yán)密的施工組織和強(qiáng)有力的技術(shù)保證措施下進(jìn)行的 ， 組織好各施工步驟 ， 準(zhǔn)備好各種技術(shù)預(yù)防措施是施工成功的關(guān)鍵。中墻施工完成后對(duì)中墻空隙進(jìn)行回填，加千斤頂支護(hù)。 (2)降低了施工難度，縮短了施工周期。 (1)本方案運(yùn)用于本工程上，在短短的 的連拱隧道內(nèi)，隧道的初期支護(hù)和二次襯砌間將轉(zhuǎn)換 4 次， 轉(zhuǎn)換過(guò)于頻繁。選擇施工方案時(shí)主要考慮以下幾個(gè)方面： (1)施工安全和結(jié)構(gòu)安全； (2)施工難度；(3)施工周期； (4)經(jīng)濟(jì)效益。 1 工程概況 廣州地鐵三號(hào)線體育西路站折返線為體育西路站站后折返線，結(jié)構(gòu)形式復(fù)雜，在 DK3+~+ 段設(shè)置了不等跨雙連拱結(jié)構(gòu)、三連拱結(jié)構(gòu)等隧道群。s main construction steps and measures are as follows: (1) The right line of doublearch tunnel hole within the return line side of temporary construction access, dualarch and the threearch in the wall construction, is pleted in a timely support for the wall, the construction to prevent bias. (2) construction of the wall lining is pleted, according to first small then big, closed into a ring principle, the right line with the step method of construction, with CRD engineering method returned a fourlane span tunnel construction. (3) When the return line side of the construction to the threearch tunnel in the wall, then in accordance with the right line of the wall construction method and the threearcharch in the wall construction, during which the right line to stop excavation until the pletion of construction of the wall. (4) The return line side of the wall construction is pleted, the right line to continue to move forward the construction. The construction method for the domestic doublearch tunnel of conventional construction method, Guangzhou Metro, Nanjing and Beijing Metro subway both applications, and can secure successful pletion of the construction of tunnels. However, examples of past engineering and construction Technology research can be found, the program has weaknesses and shortings. (1) The program used in this project, in a short span of of doublearch tunnel, the tunnel39。 Urban Underground Railroad arch tunnel Construction Technology Group Abstract Project in Guangzhou Metro Line, rightarch construction method of tunnels to explore. Subway Construction in Guangzhou for the first time put forward a doublearch tunnel to singlehole tunnel construction technology, and a single type of wall and split in the wall structure, parison and selection of Technology solutions were obtained to meet the structural safety, construction safety and Economic benefits of better Technology solutions for the future design and construction of similar projects to provide reference and reference. Keywords: doublearch tunnel group。s opening between the supporting and secondary lining will be converted four times, the conversion too frequently. (2) wall and side holes covered by waterproof layer of tunnel lining construction, steel engineering, formwork, concrete pouring required multiple conversions, the construction period up to 2 months. (3) The lining is pleted, the wall of antibias materials, equipment, support and input, resulting in higher construction costs, Economic efficiency will drop. The split in the wall construction plan The program39。不等跨連拱隧道開(kāi)挖跨度為 ，開(kāi)挖高度為 ，跨矢比為 1∶ ，小洞襯砌后跨度為 ，大洞襯砌后跨度為 ，中墻厚度為 。本著這四條原則 ,經(jīng)過(guò)施工方案的研究和論證，選出下面兩個(gè)施工方案進(jìn)行比較甄選。 (2)中墻和邊洞隧道襯砌涉及的防水層施工、鋼 筋工程、模板工程、混凝土澆注均需多次轉(zhuǎn)換，施工周期長(zhǎng)達(dá) 2 個(gè)月。 (3)降低了施工成本，提高了經(jīng)濟(jì)效益。一側(cè)施工完成后，才進(jìn)行另一側(cè)中墻施工。 對(duì)拉錨桿及加強(qiáng)錨桿 取消單一式中墻后 ,開(kāi)挖完成后中墻厚度為 ，對(duì)拉錨桿和加強(qiáng)錨桿的設(shè)置是非常必要的。由于地處廣州市繁華地段，地面建筑物密集，且隧道采用“ 0”間距開(kāi)挖，爆破時(shí)必須按照預(yù)留光面層光面微震微差爆破方案進(jìn)行施工，將爆破震動(dòng)控制在容許范圍內(nèi)。 支撐材料采用 I20 型鋼 ,焊接于兩端格柵預(yù)埋鋼板上，并采用高強(qiáng)螺栓加固。 通過(guò)總結(jié)分析，得出以下結(jié)論： (1)根據(jù)實(shí)際地質(zhì)情況大膽地改雙連拱單一式中墻為分離式中墻進(jìn)行施工，類(lèi)似于常規(guī)的超小凈距隧道施工，摒棄雙連拱隧道必須先施工中墻的常規(guī)工法，對(duì)最終襯砌結(jié)構(gòu)受力影響較小，對(duì)結(jié)構(gòu)防水更有利，并且縮短了施工工期。施 工采用的對(duì) 拉錨桿如果充分運(yùn)用預(yù)應(yīng)力加固 ,效果可能會(huì)更好。 (3)對(duì)薄弱中墻的加強(qiáng)支護(hù)也是本次施工取得成功的重要原因。 6 施工總結(jié) 通過(guò)本工程實(shí)例，證明了采用分離式中墻施工方案能夠保證連拱隧道群段的施工安全和結(jié)構(gòu)安全，工期比采用單一式中墻施工方案快 ~ 個(gè)月。 通過(guò)以上有效措施，在中墻二次爆破施工時(shí)，對(duì) 厚的中墻基本未造成破壞，順利通過(guò)了連拱隧道的“ 0”距離開(kāi)挖。在兩次開(kāi)挖中中墻均進(jìn)行注漿 ,最后開(kāi)挖完成后對(duì)中墻夾層進(jìn)行飽和注漿。通過(guò)表 2 中的數(shù)據(jù)分析可以看出，大隧道在施工時(shí)對(duì)小隧道的影響較大，如果對(duì)小斷面隧道采用必要的加強(qiáng)措施，并控制臨時(shí)支撐的縱向拆除間距，該方案是有益并可行的。中墻開(kāi)挖完成后，立即進(jìn)行二次襯砌。 采用本方案實(shí)際就是按照兩條單線的施工方法進(jìn)行， 與上一方案進(jìn)行對(duì)比后，具有如下優(yōu)點(diǎn)： (1)減少施工工序，加快工序的銜接轉(zhuǎn)換。但是對(duì)以往的工程實(shí)例和施工技術(shù)的研究可以發(fā)現(xiàn) ， 該方案還存在不足和缺陷。 2 雙連拱段施工方案比選 由于連拱隧道段結(jié)構(gòu)比較復(fù)雜，隧道斷面變化較大，施工工序繁復(fù)，施工難度高，施工周期長(zhǎng)，所以選擇一個(gè)好的施工方案對(duì)優(yōu)質(zhì)高效完成連拱隧道段的 施工尤