Abstract: In order to study the safety impact of cement mixed soil column construction on the adjacent urban rail transit structure in soft soils of Suzhou Metro Lines No. 1 to No. 8 and Line No. 11, a threedimensional finite element numerical model was established to study the impact of cement mixed soil columns on the track structure in different strata. The different proximity distances to the rail transit structure, and different reinforcement ranges across the rail transit structure are also investigated throughout the numerical analysis. The results show that the silty clay layer is scattered in the main urban area of Suzhou but widely distributed and relatively thick in Kunshan. The thicker the silty clay layer, the greater the disturbance of the cement mixed soil columns to the surrounding soil and track structure. The closer the distance between the cement mixed soil columns and the rail transit structure, the greater the deformation of the track structure. When the distance is less than 5m, the mutual influence effect increases significantly. When the cement mixed soil columns are used to improve the foundation soils underneath the rail transit structure, the deformation of the track structure increases by 4.8% for every 1m increase in the reinforcement range.

Key words: Cement-soil mixing pile, Rail Transit, Numerical Simulation, Soft Soils