天津软土地层重叠盾构隧道施工地表变形规律研究

Research on Surface Deformation Law of Tianjin Soft Ground Overlapping Shield Tunnel Construction

重叠盾构隧道施工会对地层产生二次扰动,造成地表变形加剧。为研究其地表变形规律,依托天津地铁5号线宾馆西路—环湖西路区间和6号线环湖西路—宾馆西路区间隧道工程,采用FLAC3D对两种开挖顺序进行数值模拟,并对15个地表监测断面的实测数据进行分析,得到天津软土地层重叠盾构隧道施工地表变形规律。研究结果表明:(1)本工程中上部隧道推进土压力和静止土压力比值α的合理取值范围为2.0~2.4,下部隧道α宜取1.2~1.6;(2)对地表实测数据进行拟合,可近似认为Peck公式中的沉降参数k服从N~(0.981,0.230)的分布;(3)不同开挖顺序地表沉降曲线的形状和宽度无变化,开挖顺序2的最大地表沉降增加0.8 mm;(4)“先下后上”的开挖顺序时,地表沉降槽宽度主要受下部隧道影响。

The construction of overlapping shield tunnels causes secondary disturbance to the ground,which will increase surface deformation.In order to study the law of surface deformation,this paper,relying on the Tianjin Metro Line 5 West Hotel Road-West Huanhu Road Interval and Line 6 West Huanhu Road-West Hotel Road Interval tunnel project,uses FLAC3D to numerically simulate the two excavation sequences and analyzes the measured data of 15 surface monitoring cross-sections to obtain the law of surface deformation of Tianjin soft soil layer overlapping shield tunnel construction.Research results indicate:(1)For the upper tunnel of this project,the reasonable range of advancing earth pressure to static earth pressure ratioαis 2.0~2.4,and the lower tunnelαshould be 1.2~1.6;(2)By fitting the measured surface data,it can be approximated that the settlement parameter k in the Peck formula obeys the distribution of N~(0.981,0.230);(3)The shape and width of the surface settlement curve do not change with different excavation sequences,and the maximum surface settlement of excavation sequence 2 is increased by 0.8 mm;(4)With“first down,then up”excavation sequence,the width of the surface settlement trough is mainly affected by the lower tunnel.