To investigate the mechanical behavior of the retaining column in the gravel formation a good deal of previous researches, references about deep excavations was collected, which comprised calculated experiences on mechanical parameters, such as the equivalent stiffness of retaining column, EI, and the coefficient of horizontal subgrade reaction, kh were summarized in this study. Numerical software for the deep excavation, TORSA, was employed to rate the parameters for a case of the deep excavation within Taichung basin. Analysis results indicated that, when the equivalent stiffness of retaining column, EI, that is suggested by Chu et al. was employed, the coefficient of horizontal subgrade reaction kh=6200t/m