Impact of Tamper Shape on the Efficiency and Vibrations Induced During Dynamic Compaction of Dry Sands by 3D Finite Element Modeling

Abstract

Dynamic compaction is a soil improvement method which has been widely used for the increase of bearing capacity through stress wave propagation during heavy tamping. The cost and time of project implementation can be effectively curtailed by developing a model that can be used in the design of dynamic compaction operations. The numerical models offered so far are mostly one or two-dimensional, incapable of examining the total effect of wave emission in the soil. This paper involved the three-dimensional finite element program ABAQUS employing Mohr-Coulomb failure criterion for the analysis of dynamic compaction operation. Modeling of impact on soil surface involved an initial velocity applied to the tamper nodes. Flat section and conical shape tampers with various cone angles were modeled and their effects on the efficiency of dynamic compaction for soils with different initial relative densities were investigated. Moreover, variations of peak particle velocity (PPV) induced by flat or conical tamper at different radial distances and soil densities were evaluated. The analyses were done individually for each mode over five consecutive blow counts. Comparison of the results of PPV, crater depth and crater volume for different tampers revealed the effect of tamper shape on efficiency and vibrations induced during dynamic compaction. Increasing the cone angle of conical tampers increased improvement depth and velocity of particles in all radial directions.