Proposed analytical method for predicting induced subsidence generated by dynamic compaction

Dynamic compaction is a soil improvement method in which the soil is densified by multiple impacts of a heavy rammer in contact with the ground. Through this procedure, the natural soil increases its shear strength, stiffness, and density, and reduces the potential for swelling, hydraulic conductivity, and susceptibility to liquefaction. During the improvement process, soils undergo induced settlements until they stabilize after a certain number of blows. This process is monitored by the relationship between the compaction energy and the vertical displacement, which generally exhibits a hyperbolic trend that varies mainly as a function of density, as well as the magnitude of the energy, the soil type, the degree of saturation, and the rammer’s contact area. Therefore, the objective of this article is to propose a predictive model for induced subsidence based on a hyperbolic equation derived from tests conducted on a frictional cohesive soil typical of Rio Grande do Sul. The results indicated that the model, when calibrated with the parameters λDS (dynamic displacement modulus) and ρmax (Maximum variation of induced subsidence), satisfactorily reproduced the induced subsidence curves observed in the field, making the proposed formulation suitable for both design-stage predictions and field control of dynamic compaction operations.