潛盾隧道施工引致之地表沉陷歷時曲線及深層沉陷槽

Abstract

本論文第一部分探討潛盾隧道施工引致之地表沉陷歷時曲線。本研究蒐集自1980年至2008年間，世界各國共198筆潛盾隧道施工案例之監測資料，利用雙曲線模式 模擬於不同性質土層內、以不同型式之潛盾機施工引致之地表沉陷歷時曲線。本研究整理獲得初始沉陷速率1/a之建議表及地表最大沉陷量Smax=1/b建議表，可用來檢核潛盾隧道施工引致之地表沉陷歷時曲線。本研究獲得以下3點結論： （1）由世界各國案例監測沉陷對時間資料得知，潛盾施工引致隧道中心線正上方之地表沉陷歷時曲線，可以雙曲線關係 加以模擬。 （2）由初始沉陷速率1/a之建議表得知，在非凝聚性土層中開挖之初使沉陷速率比在凝聚性土層中開挖為快。在凝聚性土層中開挖隧道，隨土層強度越弱，初使沉陷速率越快。 （3）由地表最大沉陷量Smax=1/b建議表得知，與開放式潛盾機及土壓平衡式潛盾機相比，泥水加壓式潛盾機開挖隧道所引致之Smax為最小。

本論文的第二部分探討潛盾隧道施工引致的深層沉陷。藉由分析國內外已發表的21筆施工監測深層沉陷結果，歸納出地表沉陷槽和深層沉陷槽的關係。並依據Peck（1969）提出的常態分佈曲線，建議一經驗方法檢核由潛盾隧道施工所引致的深層沉陷槽。本論文獲得以下3點結論： （1）本研究依據現地深層沉陷監測數據驗證，Peck（1969）建議的常態分佈曲線式可以描述地表及深層沉陷槽。 （2）本研究建議深層與地表沉陷槽寬度參數iz/is與深層與地表最大沉陷量Smax,z/Smax,s的關係圖。研究結果顯示隨著沉陷槽深度越深，沉陷槽之寬度越窄，沉陷槽之最大沉陷量Smax,z越大。 （3）本研究將所蒐集的國內外21組監測資料與本研究建議之經驗法預測範圍比較，得知本研究建議之經驗方法可以用來評估開放式、泥水式及土壓平衡式潛盾機於凝聚性土層中開挖隧道造成之深層沉陷。

The first part of this paper analyzes the surface settlement-time relationship due to shield tunneling. This study collects 198 sets of field measurement data due to shield tunneling cases reported in different parts of the world from 1980 to 2008. A hyperbolic model is proposed to simulate the surface settlement-time relationship due to shield tunneling constructed in different types of soils with different shields. Based on the collected data, this paper suggests empirical tables to estimate initial rate of settlement 1/a and the maximum surface settlement Smax=1/b to estimate the surface settlement-time relationship. Base on this study, the following conclusions are made. （1）Field monitored data indicate that the surface settlement-time relationship induced by shield tunneling can be properly described by the hyperbolic model. （2）The initial rate of ground settlement 1/a in the empirical table, it is found that the initial rate of settlement in sandy soil is faster than that in clayey soil. For soft clays, the initial rate of ground settlement is faster than that in clayey soil. （3）Base on the maximum surface settlement Smax=1/b table suggested in this thesis indicate, when compared with Smax due to tunneling with an open shield and an EPB shields, the slurry shield induces the smallest Smax.

The second part of this paper analyzes the subsurface settlement due to shield tunneling. Based on 21 sets of field cases, the relationship between surface and subsurface settlement troughs has been established. Based on the normal distribution curve suggested by Peck(1969), an empirical method is suggested to evaluate the subsurface settlement trough due to shield tunneling. Base on this study, the following conclusions are made. （1）Field monitored data indicate that subsurface settlement trough can be described by the distribution curve. （2）This study established the relationship between the surface and subsurface settlement trough parameter iz/is and Smax,z/Smax,s. It is concluded that at a deeper elevation, the width of settlement trough is narrower and the maximum settlement is larger. （3）The suggested empirical method can successfully estimate the subsurface settlement trough in clayey soil induced by shield tunneling.