都會區捷運系統，由於路權取得困難，有許多隧道緊鄰建物基礎或穿越建物基礎而過。位於軟弱土層中的隧道，由於盾尾間隙閉合將引起應力釋放，因而造成隧道周圍地盤變位。此種地盤變位包含垂直方向及水平方向的變位，會造成位於沉陷槽內之鄰近建物基礎的損害。因此，為了使工程師能提出有效且經濟的建物保護施工計畫，必須先行探討此種土壤移動對基礎的影響程度。 本研究利用離心模型試驗，探討於砂土層中進行隧道掘進導致之地盤變位，對鄰近隧道的既存基樁之影響。本研究分別(1)探討近接隧道基樁不含軸向荷重時，於不同深徑比的隧道開挖致使土體有移動時，距隧道中心不同距離處之樁基之荷重傳遞行為 (2)探討近接隧道基樁受到軸向荷重時，於不同深徑比的隧道開挖致使土體有移動時，鄰近隧道樁基之荷重傳遞機制行為。 研究結果顯示，通隧引致鄰近基樁之荷重傳遞行為受到隧道與樁尖之相對位置、基樁距隧道中心水平距離及樁頭加荷載與否所影響。當樁頭含荷載時，基樁之沉陷量較樁頭未加載之沉陷量大。另外，基樁也有抑制沉陷槽擴展之效果。 Tunnels are driven nearby or underpass buildings as closely as possible due to the difficulty of land use in rapid transit system construction projects in urban areas. The stress relaxation due to the closure of tail voids on tunnels in soft soils may cause the ground deformations around the tunnel. The ground deformations (including lateral and vertical soil movements) will damage nearby buildings and building protection measures must be properly taken during constructions. The load transfer mechanisms of the piles embedded in the movable soils are considerably complex and need to study in detail. A series of centrifuge model tests have been performed to assess tunneling-induced ground deformations in sandy ground and their effects on adjacent pile foundations. Two topics have been investigated in this study. First of all, the load transfer mechanism (such as bending moment, axial force and pile head deformation) of the piles has been analyzed in the different conditions, including cover-to-depth ratios, and the distance of the pile and the tunnel. Secondly, the load transfer mechanism (such as bending moment, axial force and pile head deformation) for the piles with axial load has been analyzed in the different conditions, including the cover-to-depth ratios, and the distance of the pile and the tunnel. According to results of the research, tunneling induced the load transfer mechanism of the pile that is affected by the distance of the pile from the tunnel center and the position of the pile tip regarding the horizontal axis of the tunnel center, and the pile with or without load. If the pile with load, that the settlement of the pile is larger than the pile without load. The width of the settlement trough would be suppressed by the pile nearby the tunnel.
