Primary Exploration Of Finite Element Analysis Of Large Deformation Of Dynamic Compaction Improved Foundation

Being economical, applicable and remarkable effect, dynamic compaction has been widely used. Although there have been many further theories, experiment and simulation research on it, study nowadays is still far behind the actual project demand. Characteristics of the soil under impact load have little concerned in recent literature. In view of this, improved foundation by means of dynamic compaction is studied in this paper, works have been done as follows:1. Based on LS-DYNA3D software, three-dimensional solid model is constructed using elasto plastic constitutive relation. Nonlinear theory is proposed with respect to geometrical nonlinearity in dynamic compaction. According to this theory, dynamic compaction reinforcement mechanism of loess foundation and development of plastic zone during dynamic compaction are investigated. Conclusions could be referenced in later similar projects.2. In the actual dynamic compaction, plastic deformation would be come into being in soil body. Rigid body displacement on the point of compaction is the main reason that forms the tamped pits of some depth. Based on the minor deformation assumption in classical mechanics theory that geometrical nonlinearity could not simulated the actual rigid body displacement, geometrical nonlinearity finite element method is adopted in this paper to analyze the digital simulation, therefore the defects of relevant analysis proposed before have been improved.3. Dynamic stress field and effective reinforced area of dynamic compaction are analyzed according to the data. Meanwhile, in the analysis of area of dynamic compaction, rules of dynamic stress drawn from the experiment are coincided with the fact. Some discuss and analyses are performed under 3 cases which include different impact energies, same impact energy but different combinations, and only different number of impact. Moreover, studies on the variance of effective reinforcement area and plastic area have been carried out. With the increasing number of impact, plastic area becomes more stable. Therefore, pure adding the number of impact could not reinforce the effect of dynamic compaction area, but do damage to the surroundings.4. Acceleration is chosen to be the criteria for the vibration of dynamic compaction, which proved to confirm the safety construction range. Then, time travel curve of the acceleration of the vibrating point and the attenuation rules of acceleration between horizon distances away from the tamping point are also proposed, which could evaluate the construction vibration of dynamic compaction.