Abstract: As an efficient foundation reinforcement technology, dynamic compaction technology has been widely used in various engineering constructions. However, most related theoretical research mainly focus on the tamping at a single location, and the interaction between adjacent tamping points under tamping at several locations simultaneously is rarely studied. In order to investigate the reinforcement impacts of multi-tamping under different arrangement forms of tamping location, the geometric nonlinear finite element method for large deformation and the constitutive model of “cap” in the framework of LS-DYNA are applied to analyze the degree of soil compactness under strong tamping at multi-locations. Firstly, based on the tamping experiment at a actual situation of site construction, the rationality of the model is verified by comparing the numerical results with the measured data for the lateral displacement in the soil around the tamping points. Moreover, considering two common arrangements of tamping points (i.e. rhombus-grid pattern and square-grid pattern), numerical simulations are carried out on the dynamic construction process, and compaction degree of the soil under different layouts of tamping points are studied. The results show that the compacted area between adjacent tamping locations is susceptible to multi-tamping effects, and the reinforcement degree of soil near the subsequent tamping location is better than that near the previous tamping location. Besides, the reinforcement of soil is better in regions applying rhombus-grid tamping points compared with that of square-grid pattern. In addition, by using the depth of the crater and the effective reinforcement depth, the soil affected by the strong tamping can be divided into three parts: the dilatation zone, the strong reinforcement zone and the slightly disturbed zone.

Key words: dynamic compaction, soil reinforcement, multiple tamping locations, arrangement form, relative compactness, plastic volumetric strain