Abstract: The numerical simulation method is used to analyze the reinforcement effect of dynamic compaction. The volumetric strain of reinforced foundation and the required dry density are linked. The required volumetric strain is proposed as an evaluation standard to determine the reinforcement range. It can be found from both the numerical simulation and test data that the larger impulse leads to the better reinforcement, while a fixed tamping energy can lead to different reinforcement effects. Hence, it can be concluded that the tamping impulse is more suitable to be used as a control standard of construction parameters than tamping energy. In order to study the hammer size, a modified method is proposed. Besides, it is shown that if the parameters of soil are given, settlement will be only concerned with impulse per unit hammer area; while reinforcement depth will be concerned with both the impulse per unit hammer area and the radius of hammer. The influence of tamping number is also studied. On the basis of setting the required volumetric strain as the evaluation standard and analyzing the influences of major parameters, the formulas of reinforcement range are developed with dimensional analysis method. The proposed procedure is used to predict the reinforcement range of a foundation by dynamic compaction, it is found that the calculated dry density distribution of reinforced foundation is in agreement with measurements, which demonstrates the proposed procedure is applicable.

Key words: dynamic compaction, dry density, tamping impulse, reinforcement range