Physical Modelling Of Construction Processes In The Mini-Drum Centrifuge

Hugh Richard Barker, Cambridge University
Geotechnical Engineering Group


In a series of model tests of construction processes in soft ground in the mini-drum centrifuge, it has been proved that both physical and numerical modelling techniques have now advanced to the point where much greater curvature of model geometry than had previously been regarded as acceptable can be adopted, and tests in the mini-drum centrifuge combined with routine finite element analysis can resolve problems in geotechnical engineering both in research and in teaching.

The mini-drum centrifuge at Cambridge University Engineering Department has an outer radius of 370 mm and at 1000 rpm is capable of subjecting soil models to 400 g. At this 1/400th scale, a prototype site of dimensions 850 x 70 x 50 m can be modelled around the ring channel. Multiple tests and parametric studies have been conducted on soil specimens which have an identical stress history and material properties. The soil models in the mini-drum centrifuge lie between radii of 250 and 370 mm. This variation relative to the radius of the centrifuge is much greater than in a beam centrifuge, and the variation of centripetal acceleration throughout the model is greater.

Techniques for preparing soil specimens in-flight from slurry have been developed. The Gibson et al (1967) general equation for large strain consolidation was adapted to deal with the mini-drum centrifuge conditions, and used to back-calculate values of consolidation coefficient from experimental pore pressure data. Post-consolidation soil properties were predicted and compared with experimental results. Techniques have been developed to perform excavations and construct embankments in-flight. The experimental procedures and results from fourteen tests are reported and discussed. The results were compared with analyses performed using ABAQUS finite element software.



Key words: Geotechnical engineering, centrifuge modelling, mini-drum, consolidation, embankment construction, excavation, ABAQUS, finite element analysis.