Abstract: Based on the measured data of a long excavation with retaining structures of reinforced concrete supports by using the SMW (soil mixing wall) method, deformation of retaining piles is analyzed. The analysis shows that the ratio of the maximum lateral deformation to the excavation depth is about 0.005 in the excavation supported by the SMW method. The safety factors against the basal heave of this excavation can achieve 1.4～2.0 while the stiffness of the retaining structures is smaller than that of the diaphragm wall. Double-row SMW piles can decrease the lateral deformation by 10%～20%. Through the finite element analysis, using the cement-soil grille wall to reinforce the passive zone will make the position of the maximum lateral deformation move upward and decrease the lateral deformation.