Abstract: Based on the southern pit of Senlin Park Station of Beijing Olympic Subway branch, FEM is used to study the main factors of deep excavation of subway station maintenance structure distortion, forecast the distortion of maintenance structure, complete the design of monitor project, study carry through the in-situ monitoring study of deep excavation distortion law. The results are as follows: the project of monitor of the southem pit of Senlin Park Station is practicable; the FEM calculation results of horizontal displacement of pile agrees with the in-situ monitoring results; the instance excavation method of separated layer and little portion excavation is effective to reduce space-time effect during the construction process; the steel pile brace is useful to reduce the deformation and moment of maintenance structure.

Key words: deep excavation, maintenance structure, deformation law, FEM, in-situ monitoring