Based on the quasi-three-dimensional consolidation theory,the consolidation theory of sand drains under vacuum preloading was deduced according to special loading conditions and the spatial characters of the drainage board in the process of foundation consolidation.Gradient ratio test and the single well model test were conducted respectively in consideration of the drainage board clogging which had substantial influence and could not be ignored in practical programs,in combined with the experiment results,the consolidation theory of vertical sand drains considering clogging was then established.Comparison between the measured curve and theoretical curve concerning the variation of excess pore pressure indicated a good degree of agreement,and the theoretical formula can effectively reflect the impact of process of ground consolidation in different degree of clogging at different depth.The proposed amendment consolidated theory can be promoted to apply in the improvement of related soft ground using vacuum preloading method,and obtain relatively more appropriate theoretical calculations related to practice