擁擠的都市地下空間中，進行軟弱土層隧道開挖及近接隧道施工的案例日益增多。潛盾隧道施工過程中，由於地盤應力的變化，造成鄰近周邊地盤的變形，也造成既存隧道鄰近及結構物產生下陷、傾斜甚至結構體破壞。鄰近既存隧道旁挖新隧道時，可能造成營運中的既存隧道受損，因此如何對既存隧道的保護或新挖隧道的施工掘進管理成為相當重要的工作。 本研究分為二大主題：第一部份探討單隧道盾尾間隙閉合後，地盤應力釋放所造成的隧道襯砌彎矩大小；第二部分則探討新挖隧道的潛盾機掘進推力、盾尾間隙閉合及背填灌漿壓力等施工過程，對既存隧道局部襯砌彎矩變化之關係。 試驗結果顯示鄰近新挖隧道推進時的推力及背填灌漿壓力不會對既存隧道襯砌彎矩造成太大的影響；但是新挖隧道盾尾間隙閉合時，對襯砌彎矩影響甚鉅，且較大值會發生於既存隧道頂拱、仰拱及靠近新挖隧道的側壁。 In order to reduce the environmental impacts on traffic in crowded cities, new shield tunneling nearby an exiting tunnel is increasing recently. The change of ground stresses due to tunneling process would cause the displacement of soil around a tunnel. It is a key issue to take appropriate measures to protect an existing tunnel not to be in danger during new tunneling nearby it. In the study, a series of three-dimensional parallel tunnel model with two different cover-to-diameter ratios (C/D = 2 and 3, d/D = 1.5) tested in an acceleration of 100 g was first used to investigate the bending moments on the tunnel lining during the tail voids closure. Secondly, the bending moment on an existing tunnel caused by the jacking force of shield machine, the tail voids closure and the pressure of back grouting due to new tunneling nearby were investigated. The test results in this study show that the bending moments of lining on a existing tunnel caused by the jacking force and back grouting pressure resulted from new tunneling have no significant changes compared to those already developed on the existing tunnel. However, the tail voids closure resulted from new tunneling will increase a large amount of bending moment at the crown, the invert and the side wall near the new driven tunnel on the lining of existing tunnel.
