潛盾隧道施工引致之地表沉陷速率

Abstract

本論文藉由分析國內外潛盾隧道施工案例之地表沉陷歷時曲線監測資料，說明潛盾隧道施工引致之地表初始沉陷速率與開挖土層性質之關係。本研究對台北捷運CC276及CC277標地表沉陷監測資料進行分析討論，並建議隧道中心線兩側之地表沉陷歷時曲線預測方法。本論文獲得以下五點結論： 1. 由國內外案例監測資料得知，潛盾施工引致隧道中心線上方之地表沉陷與時間關係可以雙曲線關係加以模擬 。 2. 本研究整理分析國內外潛盾施工監測所獲得之沉陷歷時資料，歸納出雙曲線參數a之建議表。參數a之物理意 義為潛盾機盾首通過測點後，地表發生主要沉陷速率之快慢。 3. 本研究發現砂性土層內之雙曲線模式參數a值較粘性土層者為小，表示潛盾隧道在砂性土層內施工造成之地 表初始沉陷速率較在粘性土層者快。 4. 本研究分析台北捷運中和線CC277標多處沉陷槽斷面後發現，隧道中心線側方之地表沉陷與時間關係可以雙 曲線模式加以描述。 5. 依非中心線上方測點之地表沉陷Sy與該測點距中心線之水平距離y之監測結果，該點雙曲線模式參數ay與y可 迴歸出一拋物線關係，利用此拋物線關係可估計地表面任一點之沉陷歷時曲線。

This paper studied the rate of ground settlement as a result of shield tunneling by analyzing the settlement-time data monitored in the field. A hyperbolic model is proposed to estimate the settlement-time relationship on both sides of the tunnel. The model was found to be in good agreement with the settlement-time field data obtained at lot CC276 and CC277 of the Taipei MRT system. Based on this study, the following conclusions can be made. 1. Field monitored data indicate that the settlement-time relationship induced by shield tunneling can be properly described by the hyperbolic model. 2. A table to estimate parameter a of the hyperbolic model is proposed by analyzing the field monitored data. The physical meaning of parameter a is the rate of primary settlement at the ground surface after the shield machine passing the monitored point. 3. The parameter a observed in sandy soil is smaller than that observed in clayey soil. That indicates the rate of initial settlement in sandy soil is faster than that in clayey soil. 4. The ground settlement data obtained from lot CC277 show that the settlement-time relationship on both sides of the tunnel can also be described by the hyperbolic model. 5. For a point at a horizontal distance y from the center line of the tunnel, the hyperbolic parameter ay and y exhibits a parabolic relationship.