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.

Method of estimating the effective zone induced by rapid impact compaction

“…In addition to the compaction performance, Thilakasiri et al 21 , Parvizi and Merrifield 22 , and Parvizi 23 performed centrifuge model tests to explore the behaviors of excess pore water pressure, wave propagation, and the stress–strain relationship for sand and organic soil at different relative densities under impact load. Ghanbari and Hamidi 24 and Allouzi et al 25 presented the finite element simulation for effective depth prediction and proposed a new evaluation method for determining the optimal blow counts required to meet the ground improvement requirements. Overall, these studies focused on verifying the rationality of the RIC compaction parameters but did not conduct advanced quality control and quality assurance method of the effective zone on site (including effective depth and suitable spacing between impact points).…”

A measuring method for layered compactness of loess subgrade based on hydraulic compaction

“…However, the price of field testing to determine the improvement effect of the hydraulic compaction method at each new site is high, and the uncertain factors in the field make it difficult to get ideal results. In addition, the numerical simulation method has been widely used in theoretical research of hydraulic compaction [40][41][42]. The mechanical parameters of the hydraulic compactor and the soil properties can be freely selected in the finite element model, which plays a good role in verifying the improvement mechanism of the hydraulic compactor for different soils.…”