泥土壓平衡式潛盾機於鬆軟土層中構築隧道時,對地表難免會造成影響,但是影響的因素種類繁多,要如何在施工時掌握關鍵的因子,才可以降低地表的沉陷,而其主要的因素為切削面地盤的土水壓穩定及背填灌漿的注入。一般來說,當潛盾機掘進地盤時,最大的沉陷量發生於環片離開盾尾時候,此時若無法掌握好背填灌漿時機與注入壓力及灌注量去填補空隙,可能會造成超過預期的地表沉陷。而切削面地盤的土水壓的平衡,則需要調整土壓倉內土壓力以平衡,避免土倉內土壓力低於外側土水壓,造成地表的沉陷。 為了瞭解潛盾施工的開挖面平衡與背填灌漿的管理,如何影響隧道施工時所造成的地表沉陷,本研究針對新莊線CK570A標潛盾隧道,在新生南路下方掘進時,隧道上方有瑠公圳排水箱涵;往信義路方向轉彎穿越民房段,從隧道環片內施做二次灌漿作為建物保護,為了探討潛盾施工對鄰房的影響,將地表監測點的沉陷值與潛盾工進搭配,分析土倉內土壓及背填灌漿的壓力與灌注量,在不同地質條件下所造成的沉陷量之影響,另外,再探討於不同地質條件的潛盾隧道案例(蘆洲線與南港延伸線),其施工時的施工變異程度與所造成的地盤變形行為。 本文分別討論開挖面平衡與背填灌漿管理,(1)開挖面平衡:潛盾隧道在直線段、轉彎段及不同地質條件的掘進時,千斤頂推力、推速及土壓倉土壓力與地盤的側向土水壓力的關係,同時探討對地盤變位的可能影響。(2)背填灌漿管理:潛盾機頂端的側向土水壓力及垂直土水壓力,與背填灌漿壓力、灌注量及設定的灌漿壓力與灌注量的搭配關係;統計分析隧道在不同土層、直線段及轉彎段掘進時,背填灌漿管理值的大小與地盤變位的相對影響。 本研究針對土倉土壓力與背填灌漿壓力,對於新莊線CK570A的直線段與轉彎段,分別進行一系列的複迴歸分析,迴歸出預測土壤漏失率的公式,(1)直線段迴歸式 y =0.632-0.520(土倉土壓力)-0.443(背填灌漿壓力),(2)轉彎段迴歸式 y =1.589-3.398(土倉土壓力)+1.002(背填灌漿壓力)。將可以回饋施工單位於潛盾施工作業時,作為制訂施工參數管理的依據之參考。
There are many factors to cause the deformation during shield tunnel construction by earth pressure balance(EBP) shield machine. The most important factors are the pressure balance of excavation face as well as the backfill grouting. In order to evaluate the interaction of construction progress and ground settlement, the SSI is use to monitor ground deformation. This study includes two major scopes (1) excavation face stability, (2) management of backfill grouting. First, for straight line and turn line, the factors such as, jack thrust, drilling speed and chamber pressure are compared with lateral soil pressure in different ground deposits. Besides, discussing the mentioned-above factors relate to ground deformation. Second, verifying backfill grouting pressure and injection volume correlate with overburden pressure above the top of shield machine. Furthermore, this study performs statistical analysis to regress the relationship between the management values of backfill grouting and the ground deformation. For CK570A lot of metro system, it can use the regression equation to evaluate ground loss ratio. In straight line, the regression equation is : y =0.632-0.520×chamber pressure-0.443×backfill grouting pressure. In turn line, the regression equation is : y =1.589-3.398×chamber pressure+1.002×backfill grouting pressure. Those achievements can feedback to practical application under shield tunnel construction.