From the real project, according to mass monitored data, the paper discusses reinforcement mechanism and effective reinforcement depth under vacuum and surcharge preloading.

By giving a review of the reinforcement mechanism of dynamic consolidation,the effective reinforcement depth and the laws of increasing and decreasing of pore water pressure,the research situation of three key factors in dynamic consolidation method have been summarized.

The effective reinforcement depth of dynamic consolidation is determined and rational suggestions are proposed for same engineering.

These formulas can also provide a new way to estimate the effective consolidation depth of the soft ground by vacuum prelo.

Terzaghi,the mechanism of improving the soft ground by vacuum well-point dewatering and preloading and the change of effective stress and effective reinforcement depth were studied.

Some conclusions concerning the effective depth of improvement(EDI) on the rubble fill sites in mountain valleys or those underlain by thin soft layers in coastal areas under various HEDC are drawn.

In this paper the simple information distribution is used for estimating the effective reinforced depth with dynamic compaction in order to broaden the ways for study of this problem and promote the appli cation and development of dynamic compaction method.