新加坡地铁C855标盾构隧道开挖面稳定性分析及泥水压力设定

复合地层中盾构隧道开挖面稳定性一直是盾构隧道工程技术难点之一。新加坡地铁环线属于典型的复合地层,并首次大规模采用泥水平衡盾构施工。文章结合地铁环线C855标段,对复合地层泥水平衡盾构施工中开挖面的稳定性分析与泥水压力设定等问题进行了探讨,基于Anagnostou和Kovari提出的楔形体模型,引进稳定数Ns概念,对沿线开挖面的泥水压力进行了分析计算,综合考虑设备性能、周边环境条件、现场组织与实施等因素给出了泥水压力设定表;并针对工程实施过程中遇到的问题,如开挖面坍塌、泥水逃逸以及降水等情况进行了分析,成果可为其它类似工程提供借鉴与参考。

Analysis of the Excavation Face Stability and Slurry Pressure Setting in the Singapore Metro Lot C855

Assuring the stability of a tunnel face has always been one of the technical difficulties regarding shield tunnels in mixed ground.The Singapore Metro loop line is located in this type of earth,and for this project a slurry earth pressure balance shield was adopted in large scale for the first time.Based on Singapore Metro Lot C855,this paper discusses the stability of the excavated face and the setting of slurry pressure during the slurry shield construction in mixed ground.In addition,it introduces the concept of the stability coefficient Ns in light of the spheroid model proposed by Anagnostou and Kovari.The analysis and calculation of the slurry pressure of the excavated face along the line are also addressed.Moreover,a table of slurry pressure settings is given concerning such factors as equipment performance,ambient conditions,site organization and execution.Finally,the paper analyzes the problems encountered during construction,including the collapse of the excavated face,slurry running and precipitation.