BEM analysis of Biot’s model for dynamic compaction of concrete in successive placement

Dynamic compaction process is analyzed by applying the boundary element method (BEM) based on Biot’s two-phase model of solid and liquid. In order to analyze mixed concrete, concrete properties at early ages are determined experimentally. Applying these properties, porepressure distribution under dynamic compaction is calculated. A feasibility of the analysis is confirmed by the compaction test. Varying the intervals between the first placement and the second, experimentally jointed beams of concrete are made and tested under bending. Analyzing BEM models of two layers, pore-pressure distributions under vibration are analyzed, taking into account the effect of placing intervals. It is demonstrated that pore-pressure distribution may not drastically change until 3 to 4 hours after placement, suggesting that the underlying layer is still responsive to vibration. Distributions of pore pressures analyzed are compared with the strengths of beams. Thus good correlation between the bending strengths of jointed beams and generation of pore pressures at the joint is confirmed. It is confirmed that low pore-pressure around the joint could result in the decrease in the bending strength, sometimes leading to nucleation of cold joints.