台北捷運新店線CH221標潛盾隧道施工引致之地盤變位

Abstract

本研究藉由收集台北市捷運新店線CH221標之監測資料,探討泥水式潛盾機 於砂質土層內施工,所造成之地盤變位.本研究得到以下幾點結論:(1)對於 以泥水式潛盾平行雙隧道施工所造成之地表沈陷,仍可以Peck-Fujita經驗 方法進行預估(2)對上下重疊之四隧道潛盾施工所造成之地表沈陷,由於隧 道間的互制作用,以Peck-Fujita經驗方法用單隧道之地表沈陷槽疊加來預 估,極可能不適用(3)對採用輔助工法之泥水式潛盾機施工,無法由Fujita (1982)之研究獲得可靠之Smax值，若直接採用無輔助工法之Smax值進行預 估,很可能會超估.(4)以泥水式潛盾機於砂質土層內開挖,施工所造成隧道 中心線正上方之地表沈陷與時間關係,亦可以雙曲線模式加以描述．(5) 將 Mair et al.(1993)所提出之單隧道施工造成之深層沈陷槽,以疊加方 式預估多隧道施工所造成之深層沈陷,並不是非常恰當. This paper studied the ground movements due to slurry shield tunnelling by analyzing the field data monitored during the construction of contract CH221 for Taipei MRT system. The following conclusions were made: 1.It's still suitable to estimate the surface settlement trough due to parallel twin tunnels constructed by slurry shield by using the Peck-Fujita method. 2.Because of the interaction of tunnels, it may not be suitable to estimate the surface settlement due to the construction of four tunnels by superpositioning settlement troughs predicted by Peck-Fujita method. 3.We could not find a Smax value for slurry shield construction with auxiliary construction methods in the Fujita's research(1982). It's possible to over predict the surface settlement if auxiliary construction method was adopted in slurry shield tunneling. 4.It is found that the time-settlement relationship induced by slurry shield tunneling can be properly described by the hyperbolic model. 5.It's not very suitable to estimate the subsurface settlement due to construction of tunnels by superpositioning subsurface settlement troughs suggested by Mair et al.(1993).