Three-Dimensional Numerical Analysis Of Dynamic Compaction For Backfilled Soil

More lands are required for constructing in mountainous towns during the process of urbanization, the numbers of the projects constructed on the soils that are got from the way of "exploded hill and filled valley" are continually increased. It is one of the problems in soil treatment that how to make these soils to satisfy the project requests such as deformation, intensity and stability, which are need to be solved urgently. Comparison with the other soil improvement methods, dynamic compaction has much technical superiority to deal with such non-uniform backfilled soils, but the correlative researches are relative fewer, therefore this is an important research subject. The mechanism of dynamic compaction and the characteristics of vibration caused by dynamic compaction are analyzed in this paper. The main contents are as follow:1. The improvement effect of dynamic compaction, aiming at coarse-grained backfilled soils, has been studied by ABAUQS using geometric nonlinear three-dimensional finite element method. Several problems which are concerned in practical engineering has been studied, the conclusions of this paper give some references for the practice.2. The plastic deformation caused by each tamping has been taken into account and the shape of the plastic zone has been identified after each drop, the parameters of soils in the plastic zone have been adjusted and the parameters of soils out of plastic zone are unconverted, which makes the base of next impact analysis. The whole process of dynamic compaction is simulated by repeating the steps mentioned above.3. The criterion for determining the reinforced zone has been obtained, namely, the soils were treated as reinforced when their value of total plastic strain is larger than 5%. The developments of plastic zone in same impact energies but different number of drops, different impact energies and different radii have been obtained, which can be used to forecast the distribution rules of reinforced zone of dynamic compaction effectively.4. The vibration characteristics of dynamic compaction in the different behaviors and the attenuation rules of acceleration and velocity between horizon distances away from the tamping point are studied, and also the factors which influence the vibration characteristic of dynamic compaction are studied. Based on the results of numerical simulation, the range of influence of vibration in backfilled soils has been achieved.