在隧道工程中，為了能夠減小在施工期間對地面交通之衝擊，目前潛盾工法已被廣泛地使用。本研究使用有限元素法，進行潛盾隧道開挖所造成地表沉陷之相關研究。考慮的開挖問題包括雙隧道與單隧道兩部分；在二向度之分析中，以平面應變來模擬新挖隧道開挖對既存隧道之影響，與盾尾間隙閉合後對地表沉陷之效應；在三向度之部分，則使用三維有限元素模型來模擬單隧道實際開挖之情形，進而探討未襯砌長度與隧道直徑比（P/D）與地表沉陷之關係。 在分析過程中是以ABAQUS有限元素程式為數值分析之工具。由於開挖時間甚短，考慮土壤為不排水狀況；在材料的組成模型上，則使用莫耳－庫倫降伏準則來描述土壤之彈塑性力學行為；分析所得之結果並與離心模型試驗之結果做一比較，以期作為日後相關問題分析之參考。 Shield tunneling has been widely used for tunnel construction in order to reduce interfering with the surface traffic. In this study, finite element method is applied to analyze the influence on surface settlement caused by shield tunneling. First, under two-dimension condition, considering the influence on an existed tunnel caused by tunneling a parallel tunnel and the effects upon the surface settlement after the closure of tail voids. On the other subject, considering a single tunnel and exploring the relation between the unlined length-to-diameter ratio(P/D) and surface settlement under three-dimension condition. Mohr-Coulomb criterion is used for simulating the elastoplastic stress-strain and undrained behavior of soil. The numerical results using “ABAQUS” were compared with the results from centrifuge model tests.
