Study on Backfilling Construction Scheme and Mechanical Properties of Shallow Excavated Tunnel with small spacing
In order to study the backfilling construction scheme of shallow excavated tunnel with small space and the influence of backfilling process on the deformation and stress of lining structure,relying on the joint reconstruction project of Jinzhou Avenue and Xingguang Avenue extension section in Yubei District of Chongqing,the finite element analysis method is used to compare two different backfilling schemes of earth stone and foam light soil,and analyze the deformation and stress of lining structure combined with the field monitoring data.The results show that the structure deformation and stress backfilled by the foam light soil can meet the bearing capacity requirements compared with the earth stone backfilling.The displacements of roof,corner and baseplate are reduced by 24％,29％,11％,and do not exceed the allowable displacement value.The tensile stress is reduced by 41％,39％,27％.When the backfilling depths of lining structure are 0,2,4,6 m,the change trend of tensile stress in each part of the structure is slow,and the deformation and stress are basically and symmetrically distributed.which can effectively avoid the tensile shear failure of the structure.Considering the convenience of construction,safety of structure and compacting degree of backfilling soil,the backfill scheme of the tunnel is the layered backfill with foam light soil in special parts and the layered backfill with soil and stone on both sides and the top.This scheme is used for backfilling construction on site,and the structural displacement and stress exceed the allowable value.Due to the soil arch effect,the calculated value on site is less than the simulated value.
excavated tunnel with small spacingfoam light soilnumerical analysisfield measurement
NETL
NSTL
万方数据
维普
