I arrived in Perth in mid-October 2018, for a 10 week visit to the National Geotechnical Centrifuge Facility (NGCF) at the Centre for Offshore Foundation Systems (COFS), University of Western Australia (UWA). Arriving to Perth in springtime was lovely. It was sunny and warm and perfect for exploring Perth’s many beaches and parks – when I wasn’t in the lab, of course!
During my visit, I carried out centrifuge testing to explore stress level effects for monopiles under both monotonic and cyclic lateral loading. These tests complement laboratory tests I performed at Oxford during the first few years of my PhD, and should provide valuable insight into the monopile’s response to lateral loading, to help inform improved design methods.

Geotechnical centrifuges allow the g-level (acceleration) experienced by geotechnical models to be increased, to simulate large-scale stress-levels with small-scale models. For example, the 40 mm diameter model monopile I used for my experiments simulated a 3.2 m diameter monopile when the centrifuge operated at 80g. During my visit I used the new 10 m diameter beam centrifuge at the NGCF, which is capable of spinning up to 2400 kg at 100g.

Figure 1 – 10 m diameter beam centrifuge at the NGCF

Over the first month I got to grips with operations at the NGCF, designed equipment modifications and discovered how complicated things can become when your apparatus needs to perform at both 1g and 80g. Preparation for the experiments was challenging and required lots of troubleshooting, but with excellent support from the technicians and academics at COFS, preparations were complete by early December.

We began centrifuge testing on December 5th. I was very nervous the first time we span the centrifuge – as I wondered whether we’d tightened all the nuts correctly and if my crimped wire connections would be up to scratch – but for the centrifuge technicians, this was just another typical day. The NGCF is a very busy facility; during my visit five other researchers (including 2 other international visitors) were also carrying out centrifuge testing campaigns.

Figure 2 – Close-up of loading and displacement measurement set-up on the centrifuge

The centrifuge testing went remarkably smoothly, and we completed 20 monopile tests and 12 CPTs (to characterise the soil samples) with a few days spare before I flew home for the Christmas break. I am currently post-processing the results and writing a report on the findings, which we hope to publish soon.

Beside the centrifuge testing, the visit was a great opportunity to experience life at a different university, on the other side of the world. Everyone at COFS was very welcoming, and I learnt a lot through discussions with academics, PhD students and technicians. I am also very grateful to fellow PhD students who helped in the lab, treated me to Aussie BBQs and showed me a little of Western Australia. Many thanks go to Prof. Fraser Bransby and Prof. Christophe Gaudin at UWA for hosting the visit.

Figure 3 – Exploring beaches near Margaret River, Western Australia

Iona Richards