Arbeitsintegrierte Verdichtungskontrolle während der Rütteldruckverdichtung

Vibroflotation is an established ground improvement technique for granular materials. It densifies loose sands by means of shear and compressive deformation processes imparted by the horizontal vibrations of a vibrator probe at the required soil depth. The field experience and empirical relations used for the design of vibroflotation processes prompt further study and analysis. Numerical simulations of the method help provide insight into the process. A coupled Eulerian–Lagrangian framework was used to model the compaction process. The compaction process was modelled based on the pilgrim step method for a depth range from 25 m to 10 m. A hypoplastic constitutive model was used to characterise the stress–strain behaviour of the fine sand. Numerical results were validated against in-field cone penetration test measurements made before and after the compaction of fine sand in east Germany. The validation was followed by a parametric study in which the following were evaluated in terms of their effects on the extent and degree of compaction: frequency, relative density, shape of vibrator, spacing of compaction points, nature of compaction process and type of sand.

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Optimisation of vibroflotation by amplitude in 1g tests and coupled Eulerian–Lagrangian simulations

Nagula

Katt

Grabe

2021

International Journal of Physical Modelling in Geotechnics

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Vibroflotation includes densification of loose sands by means of shear deformation processes imparted by horizontal vibrations of vibrator probes. 1g model tests replicating the vibroflotation process were conducted using a model vibrator to identify online compaction control parameters. The effectiveness of the compaction was evaluated by means of a cone penetration test. An accelerometer and a trigger were installed in the model vibrator to measure the amplitude of the vibrator and the phase angle of the eccentric mass during compaction. The variation of amplitude and phase angle during compaction was studied and it was observed that amplitude and phase angle reduced with the increasing density of sand. Two tests were conducted with and without considering amplitude as a compaction control parameter. One test included a pre-determined fixed compaction time and the other used amplitude as a compaction completion indicator. It was observed that tests conducted considering amplitude as a compaction control parameter led to reduced compaction time. Coupled Eulerian–Lagrangian-based numerical simulations were carried out to study the feasibility of amplitude-controlled compaction under realistic stress state conditions.

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Arbeitsintegrierte Verdichtungskontrolle während der Rütteldruckverdichtung

Cited by 3 publications

References 10 publications

Methoden zur Baugrundverbesserung

Methoden zur Baugrundverbesserung

Field measurements and numerical analysis of vibroflotation of sand

Optimisation of vibroflotation by amplitude in 1g tests and coupled Eulerian–Lagrangian simulations

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