Deformation And Control Technology Of Double Shield TBM Lining Structure In Metro Tunnel

At present,with the rapid development of the Mass Transit Railway(MTRC),most metropolitan areas with a population of more than 1 million have built subways to ease and improve urban traffic tensions,and China is no exception.In subway construction,the advantages of TBM construction technology are becoming more and more obvious.Double shield TBM has developed rapidly in the field of urban rail transit because of its good adaptability and safety in hard and complex strata.As the permanent supporting structure of TBM tunnel,the excessive displacement of lining segment support structure leads to the damage of staggered table,cracks and bolts,and may further lead to the damage of waterproof layer of the structure,resulting in water seepage,leakage,water inrush and other quality problems in the tunnel.Affect tunnel quality and service life.Based on the double shield TBM project of Shenzhen Line 8 subway tunnel,this paper studies the deformation law and control measures of TBM tunnel lining structure,and draws a conclusion:(1)through the analysis of the field monitoring data of typical sections,it is found that the deformation of TBM tunnel lining structure has strong temporal and spatial distribution characteristics,and the deformation-time curve of lining structure is inverted "factory" type.The variation characteristics of this curve are mainly manifested in two aspects: 1)sharp deformation period and 2)slow deformation period.However,the deformation of lining structure mainly occurs in the period of rapid deformation,and the deformation of lining segment tends to be stable after 3 ~5 days.(2)the FLAC3 D numerical simulation software is used to simulate the excavation process of double shield TBM under different buried depth,grouting pressure and excavation spacing.The results show that: With the increase of buried depth and excavation spacing,the maximum displacement of tunnel lining structure appears in the arch roof position,and increases with the increase of buried depth.With the increase of excavation distance between tunnels,the maximum displacement of lining structure decreases and tends to be stable.When the thickness of soybean gravel filling layer is not uniform,the stress will concentrate to the weak part,the displacement of the segment on the weak side will increase,and the displacement of the segment on the thicker side will decrease.In a certain range,the deformation of lining structure increases at first and then decreases with the increase of pressure.(3)according to the principle and method of deformation control of lining structure in TBM tunnel,the measures to control the deformation of lining structure are put forward.The deformation control of lining structure is controlled by the optimization of construction parameters,such as grouting pressure,excavation spacing and so on.