The Influence On The Deformation And Optimization Design Of Pre Axial Force For A Deep Foundation Pit

The safety of deep foundation pit engineering has always been a big obstacle in the development of foundation pit and construction technology. Previous engineering experience have shown that reasonably steel support pre axial force could control deformation of foundation pit and improvement the safety of foundation pit economically and effectively.This paper based on the foundation pit engineering of Beijing subway line 16’Wengyanglu station, Refer to the foundation pit deformation monitoring data, calculate the optimization value of the pre axial force by FLAC3 D,and based on the reference to previous research results, through further analysis this paper put forward theory that pre axial force is applied to balance lateral static soil pressure Derived formula of the optimal Steel support pre axial force value and the optimal Steel support’ horizontal distance.Calculated the optimization value of pre axial force of the first layer is 712KN; the second layer is 1417KN; the third layer is 1913 KN. Derived formula of the optimal Steel support pre axial force value N=(γh~2)/2D and the optimal Steel support horizontal distance D=(2(0.5～0.8)N_b)/(γh~2).Preliminary verified the applicability of the formula, provides an effective way and meaningful discussion for the designing of the foundation pit engineering pre axial force and the development of the theory of foundation pit supporting.