1月20日，由中(zhong)國(guo)鐵建(jian)所(suo)屬(shu)中(zhong)鐵十四局集團施工(gong)(gong)的(de)長(chang)沙(sha)地鐵3號線盾構隧道(dao)成功(gong)穿越(yue)目前國(guo)內(nei)最長(chang)最復雜(za)水(shui)下(xia)(xia)溶(rong)洞區，開創了(le)國(guo)內(nei)同(tong)類工(gong)(gong)程施工(gong)(gong)先河(he)，標志(zhi)著國(guo)內(nei)水(shui)下(xia)(xia)隧道(dao)施工(gong)(gong)難(nan)度大、風險高(gao)的(de)控(kong)制性難(nan)點成功(gong)攻(gong)克，為地鐵最終開通運營奠定了(le)基礎。

搭設水上鋼平臺(tai)

長沙(sha)地鐵3號線穿越湘江(jiang)巖(yan)(yan)溶(rong)(rong)(rong)(rong)(rong)發育區(qu)(qu)位于國(guo)家5A級(ji)(ji)景區(qu)(qu)橘子(zi)洲梅園內(nei)及湘江(jiang)西河汊，地處湘江(jiang)水(shui)源二級(ji)(ji)保護地帶(dai)，總(zong)長為323米(mi)(mi)，主要(yao)為3億年前泥盆紀(ji)形(xing)成的(de)石灰巖(yan)(yan)及白(bai)堊紀(ji)形(xing)成的(de)砂礫巖(yan)(yan)。該施工(gong)區(qu)(qu)域地質復雜(za)，號稱“地質博物館(guan)”。巖(yan)(yan)溶(rong)(rong)(rong)(rong)(rong)區(qu)(qu)宛如一個(ge)巨大(da)的(de)蜂巢，溶(rong)(rong)(rong)(rong)(rong)洞見洞率高達(da)(da)80.6%，是普通巖(yan)(yan)溶(rong)(rong)(rong)(rong)(rong)區(qu)(qu)見洞率的(de)幾倍，平均每隔1米(mi)(mi)就有一個(ge)溶(rong)(rong)(rong)(rong)(rong)洞，為國(guo)內(nei)外罕見。整個(ge)橘子(zi)洲巖(yan)(yan)溶(rong)(rong)(rong)(rong)(rong)區(qu)(qu)溶(rong)(rong)(rong)(rong)(rong)洞及溶(rong)(rong)(rong)(rong)(rong)蝕空洞分布位置及深度(du)無(wu)規律，構(gou)造形(xing)態不同，溶(rong)(rong)(rong)(rong)(rong)洞埋(mai)深最淺的(de)2.5米(mi)(mi)，最深達(da)(da)22.46米(mi)(mi)，相(xiang)當(dang)于8層(ceng)樓高，每天約(yue)有4000立方(fang)米(mi)(mi)涌水(shui)。

“這是長(chang)沙(sha)地(di)鐵施(shi)工中(zhong)難度最(zui)為(wei)(wei)集中(zhong)、巖溶地(di)質最(zui)為(wei)(wei)復(fu)雜(za)的區(qu)(qu)間，為(wei)(wei)了適(shi)應高水(shui)(shui)壓、長(chang)距離、大埋深和(he)湘江復(fu)雜(za)水(shui)(shui)下巖溶發育區(qu)(qu)的施(shi)工，有效控(kong)制地(di)面(mian)(mian)沉(chen)降，保護好湘江水(shui)(shui)資源環(huan)境(jing)，項目(mu)選用(yong)了國(guo)內(nei)先(xian)進的泥水(shui)(shui)平(ping)衡盾構。”中(zhong)鐵十四(si)局長(chang)沙(sha)地(di)鐵3號線項目(mu)負(fu)責(ze)人師(shi)慶彬表(biao)示。項目(mu)先(xian)期對溶洞(dong)區(qu)(qu)進行地(di)表(biao)注漿(jiang)(jiang)和(he)江面(mian)(mian)注漿(jiang)(jiang)填充處理，溶洞(dong)區(qu)(qu)共計注漿(jiang)(jiang)鉆孔3000余(yu)根，注漿(jiang)(jiang)約8萬立方米。

穿(chuan)越湘(xiang)江溶洞區示意圖

項(xiang)目部(bu)成立(li)科技攻關小組，與(yu)中南(nan)大(da)學、山東大(da)學聯合(he)，開展施(shi)(shi)工(gong)(gong)(gong)(gong)研究與(yu)科技攻關。聘請國內知(zhi)名專家對盾構穿(chuan)越(yue)巖溶(rong)發育地段風險進行充分論證，最(zui)終確定(ding)了(le)水(shui)上(shang)鋼平(ping)臺施(shi)(shi)工(gong)(gong)(gong)(gong)方案。中南(nan)大(da)學教授(shou)、湖(hu)南(nan)省巖石(shi)力(li)學與(yu)工(gong)(gong)(gong)(gong)程學會副理(li)事長陽軍生表示，“江(jiang)面搭(da)設(she)固定(ding)平(ping)臺直接處理(li)，溶(rong)洞(dong)處理(li)施(shi)(shi)工(gong)(gong)(gong)(gong)周期短，汛期影響小，對行洪影響小，施(shi)(shi)工(gong)(gong)(gong)(gong)風險低。”項(xiang)目部(bu)通(tong)過搭(da)建(jian)近(jin)六千平(ping)方米的施(shi)(shi)工(gong)(gong)(gong)(gong)平(ping)臺，將溶(rong)洞(dong)處理(li)由水(shui)上(shang)施(shi)(shi)工(gong)(gong)(gong)(gong)化為“陸地”施(shi)(shi)工(gong)(gong)(gong)(gong)等(deng)系(xi)列方案，有效解決了(le)淺溶(rong)洞(dong)區鋼管樁打設(she)的技術難題。

在(zai)掘(jue)進(jin)(jin)(jin)過程中，項目部聯合中南大學，采(cai)用(yong)神經網絡預演盾(dun)構掘(jue)進(jin)(jin)(jin)參數，在(zai)盾(dun)構機內增設超前探(tan)測(ce)(ce)鉆孔(kong)，對(dui)掘(jue)進(jin)(jin)(jin)前方進(jin)(jin)(jin)行至(zhi)少15米的探(tan)測(ce)(ce)，有效規避了施(shi)工(gong)風險。項目通過加強渣樣對(dui)比分(fen)析、嚴格控(kong)制泥漿(jiang)(jiang)指標等措施(shi)，對(dui)掘(jue)進(jin)(jin)(jin)參數不斷總結和優化(hua)；嚴格控(kong)制同(tong)步注(zhu)漿(jiang)(jiang)，保證注(zhu)漿(jiang)(jiang)壓力和注(zhu)漿(jiang)(jiang)量，及時跟進(jin)(jin)(jin)二次注(zhu)漿(jiang)(jiang)，提升盾(dun)構掘(jue)進(jin)(jin)(jin)管控(kong)水(shui)平。

此次盾構(gou)長距離(li)(li)成功穿越溶洞區，填(tian)補(bu)了(le)泥水(shui)(shui)平衡盾構(gou)機使用的(de)空白，對今后相同(tong)條件下(xia)的(de)盾構(gou)施(shi)工技術(shu)管控具(ju)有重要(yao)意義，也為(wei)國內(nei)類(lei)似水(shui)(shui)下(xia)長距離(li)(li)溶洞區條件下(xia)的(de)工程施(shi)工提(ti)供了(le)寶貴的(de)經(jing)驗。