GeoCentrifuge

The Deltares GeoCentrifuge

Because civil engineering structures are large by definition, scale models are very useful to carry out further research. With these scale models, we can simulate field situations in a controlled and reproducible manner. This way, it is possible to monitor the performed calculations at an early stage of the project. In addition, using scale models reduces or even eliminates possible design risks.

Using scale models in the GeoCentrifuge can result in a substantial reduction of research costs and time needed. By enhancing gravity, soil consolidation, for instance, is performed much faster compared to field experiments.

When working with scale models, a number of practical problems are solved by enhancing gravity. A pile, for instance can be scaled down easily, but for the surrounding soil it is a different story. Soil consists of grains and models cannot replicate reality accurately without affecting the soils physical properties unless gravity is artificially enhanced. Enhancing gravity is also necessary to create proper soil stress in a scale model.

Therefore, the Deltares Geotechnical Test Centre has the GeoCentrifuge, a facility that is unique in the world because of its specifications. In close cooperation with our Clients, scale models are designed and constructed by our Deltares experts. It is possible to monitor the tests conducted in the GeoCentrifuge on screen or trough data.

Projects

Piping research

Rijkswaterstaat's SBW (Strength of and Loads on Flood Defence Assets) research programme looking at Water Defences includes a component dealing with piping, the phenomenon in which water seeps under a dike, gradually undermining the structure as a whole. The research started with small model experiments. A piping event was then modelled on the 1:100 scale in the GeoCentrifuge. In 2009, there was a field experiment at the IJkdijk.

Anchor chain tests

The idea behind the anchor chain tests is to measure the penetration and forces exerted by anchors and anchor chains cutting into cover layers protecting pipelines. Usually, pipelines are protected by berms built of broken rock against buckling and by damage caused by anchoring vessels. The design of the thickness of the cover is not based on a fundamental understanding of how the chains cut through the broken rocks. The required thickness of the rock layer is mainly the result of years of working experience, with a considerable safety margin.

Collision tests on a bridge pier

The Incheon bridge links the South Korean airport of the same name to the mainland. These structures – which are 40 metres high and 30 metres in diameter – protect the bridge piers against ship collisions. Deltares conducted collision tests on the ‘dolphins’ at a scale of 1:200 and 200G.

Short sheet pile wall

When dikes get too weak, inner berms are sometimes needed on the side facing the polder. However, there is not always enough space, for example when there are dwelling houses nearby. In these circumstances, an option is to install a short sheet pile wall. To demonstrate how sheet piling of this kind works, experiments took place in the GeoCentrifuge.

Specifications GeoCentrifuge