土壓平衡盾構(gòu)隧道施工引起的地層損失及影響因素

劉金慧+丁萬(wàn)濤+戴尊勇+王煥+賈開(kāi)民

摘 要：收集中國(guó)已有地表沉降監(jiān)測(cè)數(shù)據(jù)及土體損失率統(tǒng)計(jì)分析數(shù)據(jù)，結(jié)合長(zhǎng)株潭城際高鐵Ⅱ標(biāo)樹(shù)木嶺盾構(gòu)隧道進(jìn)口樹(shù)木林車(chē)站區(qū)間16個(gè)監(jiān)測(cè)斷面數(shù)據(jù)及其詳細(xì)地層信息，分析土壓平衡盾構(gòu)隧道施工引起的地層損失規(guī)律影響因素。分析表明，土壓平衡盾構(gòu)隧道施工引起的土體損失率的累積概率較好的服從對(duì)數(shù)正態(tài)分布；土體損失率隨著埋深或深徑比的增大，呈現(xiàn)逐漸減小并趨于穩(wěn)定的趨勢(shì)，且兩者關(guān)系可近似采用冪函數(shù)擬合；當(dāng)H大于20 m或H/D大于3.25時(shí)，土體損失率基本穩(wěn)定在075%附近，且對(duì)應(yīng)地層信息表明盾構(gòu)隧道施工時(shí)其上覆巖層呈現(xiàn)拱效應(yīng)，說(shuō)明盾構(gòu)隧道施工中其頂部土層成拱效應(yīng)可較好的控制土體損失；土體損失率或名義土體損失率隨著盾構(gòu)開(kāi)挖通過(guò)時(shí)間的增加而逐漸增大，且趨于穩(wěn)定，說(shuō)明固結(jié)變形對(duì)名義土體損失率的影響較大，最大可達(dá)瞬時(shí)沉降所引起土體損失率的4.58倍。

關(guān)鍵詞：盾構(gòu)隧道；土體損失率；固結(jié)變形；瞬時(shí)沉降

中圖分類(lèi)號(hào)：TU43

文獻(xiàn)標(biāo)志碼：A 文章編號(hào)：1674-4764（2017）05-0001-08

Abstract：The observed data of surface settlement and the statistical analysis data of ground loss ratio caused by EPB shield tunnel construction are collected. Combining with the monitoring data and stratigraphic information of the sixteen sections in the interval from tunnel import to Shumuling station of the Chang-Zhu-Tan intercity high-speed rail II standard， the ground loss and its factors induced by EPB shield tunnel construction are analyzed. The results show that the cumulative probability of ground loss ratio caused by EPB shield tunnel construction better obeys lognormal distribution； with the buried depth and the depth to diameter ratio increasing， the ground loss ratio decreases and tends to be stable， and the relationship between the ground loss ratio and the tunnel buried depth & the depth to diameter ratio can be approximately expressed by power functions； when H greater than 20m or H/D greater than 3.25， the ground loss ratio is basically stable near 0.75%， and the corresponding stratigraphic information indicates that the overlying strata in the shield tunnel is in the arch effect when constructing. So， it shows that the arch effect of the upper soil layer in the shield tunnel construction can be better control the ground loss ratio. With the increase of the time of shield tunneling through face， loss rate and nominal loss rate of the soil mass gradually increase and tend to be stable. It indicates that the consolidation deformation has great influence on the nominal ground loss ratio， and the maximum value is 4.58 times of the ground loss ratio caused by instantaneous settlement.

Keywords：shield tunnel； ground loss ratio； consolidation deformation； instantaneous settlement

盾構(gòu)法隧道施工會(huì)打破地層原有的應(yīng)力平衡，引起周?chē)馏w變形，對(duì)周邊環(huán)境產(chǎn)生危害，盾構(gòu)施工引起的地層變形成為學(xué)者們一直關(guān)注的熱點(diǎn)問(wèn)題[1-3]。

在施工過(guò)程中，經(jīng)常采用監(jiān)控量測(cè)實(shí)時(shí)掌握開(kāi)挖所引起的地表動(dòng)態(tài)變形，并通過(guò)繪制變形時(shí)間（距離）關(guān)系曲線(xiàn)評(píng)估和預(yù)判開(kāi)挖面的穩(wěn)定狀態(tài)。變形時(shí)間（距離）關(guān)系曲線(xiàn)主要包括沿橫斷面和縱斷面兩種曲線(xiàn)，其中沿橫斷面的地表沉降曲線(xiàn)一般習(xí)慣稱(chēng)之為“沉降槽”?！?br>