潛盾機開挖向前推進,引致土體內部狀況之改變,造成地盤在垂直、側向及縱向三個方向上的變位,實際上乃為一個三度空間之問題。本文以臺北捷運系統CH221標為例,利用Plaxis 3D Tunnel套裝軟體,以三向度分析模型來模擬實際之單孔及雙孔隧道開挖情形,探討Plaxis 3D Tunnel程式中所需輸入之隧道斷面縮減率(Contraction,%)與一般經驗公式所使用之土壤漏失(Ground Loss)及潛盾隧道施工引致地表沉陷之間關係,另針對雙孔隧道斷面,嘗試以不同之隧道組合疊加,進行地表沉陷曲線之推估及比較,期能藉由分析成果驗證Plaxis 3D Tunnel應用於潛盾隧道施工引致地表沉陷分析之適用性,並將使用經驗分享及傳承。
The study takes the point of departure of the Contract CH221 which is the Hsintein Line of the Taipei Rapid Transit Systems (TRTS) to evaluate the ground surface settlement due to shield tunneling. Drawing upon Plaxis 3D Tunnel, the 3D Finite Element Method analytic software, we employed the numerical analysis results of single tube tunnel sections to establish correlations between contraction of the tunnel and ground loss. Ground loss is one of the significant variables when an empirical equation is used to evaluate ground surface settlement due to shield tunneling. The correlations between contraction of the tunnel and ground loss were also applied to the numerical analyses of both the section of double-tube tunnels with the same elevation. Meanwhile, a further exploration was made by different combination of analyses. The study also presents the collected cases in Contract CH221 TRTS in order to exhibit the feasibility of Plaxis 3D Tunnel in its evaluation of ground surface settlement due to shield tunneling. The research results provide the Plaxis 3D Tunnel users with concrete empirical examples for future studies.