Advanced Simulation of Vibro-Replacement

To support the insights gained from measurements related to vibro-stone column installation, validated numerical approaches can be used. These enable a deeper understanding of the underlying physical processes and allow for the optimization of the execution process in ground improvement through vibro-stone columns.

Currently, no adequate approach exists for the numerical simulation of vibro-stone column installation (Kirsch and Kirsch, 2016). In particular, the changes in soil state resulting from the column installation process cannot be realistically represented. The simulation of a simple (cyclical) cavity expansion neither accurately captures the internal force transfer within the column nor the stresses transmitted to the surrounding soil.

This project develops an innovative simulation method for vibro-stone column installation that represents a breakthrough in research and offers the potential to improve the cost-effectiveness of the procedure. In this approach, the gravel material is modeled discretely, i.e., individual grains are represented separately. The surrounding soil, on the other hand, is modeled using conventional continuum mechanics. The discrete particles of the column interact with the surrounding soil via contact mechanics algorithms implemented in an in-house code (Staubach et al. 2022a, 2022b).

This discrete modeling approach enables the simulation of pressing individual grains into the soil under pressure, reproducing the actual installation process (including modeling of the vibrator itself). This allows for a realistic determination of stress changes in the surrounding soil. Additionally, the method permits the consideration of arbitrary particle shapes of the gravel, as well as effects from abrasion and particle breakage.