Finite-element model to simulate ground-improvement technique of rapid impact compaction

Abstract

Rapid impact compaction (RIC) has been used effectively as a ground improvement at medium depth technique for granular soils. RIC is normally used to increase bearing capacity, reduce potential settlements and mitigate liquefaction. This paper presents a calibrated three-dimensional cap-plasticity finite-element model (FEM) to simulate ground improvement using RIC. The results of 107 RIC field compaction points were used to calibrate and validate the FEM. Numerical outcomes of the FEM showed good agreement with the field compaction results. The FEM was further used to propose a relationship between the soil bearing capacity and the number of hammer blows for engineering practice. This is attained by performing pushover analysis of a spread footing resting on RIC improved soils with different numbers of RIC blows. The RIC, circular 1·5 m anvil was used as the spread footing. The applied stresses that produced 25 mm settlement are considered the improved soil bearing capacity. Also, the paper presents a recommendation for the optimum number of blows after which more blows will have no significance.