NZ Geomechanics News

NZGS Symposium 2021

CLOCKWISE FROM TOP LEFT: Eleni Gkeli and Ross Roberts opening the Symposium. Morning of Thursday 24 March – The main event begins!! The first online keynote speech by Sissy Nikolaou. MBIE and the Geotechnical Module update project panel answer the questions of the delegates.

The 2021 NZGS Symposium in Dunedin on 25 and 26 of March 2021 will remain in our memories as one of the most eventful in the history of NZGS. Due to the impacts of the COVID-19 pandemic, the in-person event was uncertain throughout 2020 and eventually had to be postponed from its original date in October 2020. But in my view, it will also remain as one of the most anticipated, with engagement and enthusiasm by the delegates and supporters that humbled the organisers. 

Due to the ban on international travel, the Symposium trialled a hybrid format including online and live presentations, with all international invited and keynote speakers (and some of the delegates) joining online. This was a first-time experience for the NZGS Symposium that I am sure will find more application in the future. In the times of the pandemic, our industry showed its resilience and adaptability to different ways of working and this format seemed to be well received by the delegates.  

The theme of the Symposium was “Good grounds for the future” inspired by the profound changes that our world has been experiencing. It was a call for reflection on what our future will look like and how we can learn from the successes and the failures of our past to shape a better future for us and the generations to come. 

The Symposium started with a pre-symposium event perfectly aligned with its theme. A half day workshop on the 23rd of March in Queenstown discussed landslides and current and future trends in slope monitoring. A mix of in-person and virtual presentations from Chris Massey and Peter Amos from New Zealand and Joseph Wartman, Michael J. Olsen and Mark Vessely from the United States provided valuable insight into the state of practice of slope monitoring both now and in the future. The workshop was oversubscribed with around 80 participants, and concluded with the promise that the discussion will continue.

The following day, the group of 80 split into two and loaded into buses for a field study with one group heading to Macraes Mine and the other to the Clyde Dam through Kawarau and Cromwell Gorges. There were stops along the way to look at slope hazards and features of interest.

The Macraes Mine trip was led by David Stewart and involved a brief stop at the Deadmans Point rockslide near Cromwell, then through the Maniototo to Macraes Gold Mine. There, the group attended a presentation from Oceana Gold staff on the mine site and various pits that have been mined over the years. They then travelled into the 280m deep Frasers Pit for a first-hand look at the scale of the mine and the operations and activities being undertaken.

The Clyde Dam trip was led by Don Macfarlane with support from David Barrell of GNS. Contact Energy provided a tour of the dam and one the slope monitoring tunnels. The group was lucky enough to observe a test of the dam spillway gates, while the buffet lunch at a local café was certainly one of the highlights. Thank you to David and Don for organising, as well as to Contact Energy and Oceana Gold for making these field trips possible.

At the completion of the field trips, the two groups met at Hindon Siding to board the spectacular Taieri Gorge Railway, enjoy refreshments, catch up on the day and travel into Dunedin for the Welcome Reception, which took place at the Toitu Otago Settlers Museum. A tour through the museum exhibition, which is full of Dunedin and Otago Region history, was offered to the reception attendees, whose turnout on the evening was exceptional!

The main Symposium event officially kicked off on the 25th of March. The Dunedin Centre, the venue in the heart of the city with the unique baroque style and architecture hosted us for two full-on days of technical program. Apart from the keynote talks, the special sessions and the interactive plenary sessions, the Symposium included about 60 oral presentations and 23 poster presentations. 

The exhibition was held in the impressive Town Hall decorated by ‘Norma’, the symphonic organ built in 1919. The organising committee was pleased to see all the exhibition spaces taken by the industry representatives, who finally had the opportunity to interact with the delegates in person in the breaks of the intensive technical program. The organising committee and NZGS sincerely value the commitment and patience of our exhibitors and all the sponsors through the bumpy journey of organising; the event would not have been possible without their support. 

Four keynote talks by renowned international experts, delivered virtually, were focused on hot topics of our profession and attracted the interest. Dr. Sissy Nikolaou, in the opening keynote talked about the future of engineering resilience and functional recovery. Professor Ross Boulanger demonstrated the use of numerical modelling and a new user-defined strain-rate dependent constitutive model to provide reasonable approximations of undrained creep behaviours that
can be important for static slope stability evaluations.

The keynote of George Gazettas discussed the performance and design of rigid gravity walls under strong seismic shaking; the talk revealed some of the limitations of the pseudo-static methods of analysis and investigated the main causes of the poor performance of these walls when they constitute quaywalls in harbours. Dr. Chris Haberfield discussed the design of retention systems for basements in rock in tight urban environments. 

A good part of the Symposium was focused on regulation and guidance. The Chief Engineer of MBIE Mike Kerr and Kieran Saligame discussed balancing between regulation, community risk and community impact and informed us about MBIE’s upcoming projects. Mike Stannard and Misko Cubrinovski updated us on the Geotechnical Modules finalisation project and in particular on the proposed changes to the Module 1 and the earthquake hazard. 

Collaboration with our colleague structural engineers was the focus of a panel discussion on the second day of the Symposium. A lively and stimulating debate on our collaboration and soil structure interaction for the best outcome of the project was led by a panel of experts including the SESOC President Hamish McKenzie, Dr Alexei Murashev, Stuart Palmer and Dejan Novakov. The duration of the session was not enough to cover all the questions from the delegates. These remain in our agenda and NZGS will seek opportunities to organise future similar events in various centres to continue the discussion. 

Our Symposium made a first step in exploring the role of our profession regarding climate change and sustainable geotechnical engineering with a few papers on environmentally sustainable solutions. NZGS, however, aims to continue this discussion with the industry, and looks forward to more fora and Symposia in the future exclusively devoted to sustainable geotechnical engineering practice.

The gala dinner of the Symposium, another oversubscribed part of the event, was delightful. The NZGS Chair Ross Roberts presented their well-deserved Life Member awards to Stuart Read and John Scott and the JW Ridley Geomechanics Paper Award to Dr. Mark Stringer for his paper on “Separation of pumice from soil mixtures”.

I want to close this report with a special reference to the presentations delivered by the four young geotechnical professionals Jessie Beetham, Christoph Kraus, David Rowland and Michelle Willis in the YGP special breakfast on the second day. These papers were voted as best papers in the mini-Symposia that the local NZGS branches organise around the country and NZGS supported the four to attend and present in the main Symposium. I was impressed by the quality, the ingenuity, the empathy and the high technical level of all four presentations. By listening to these, I felt very confident that the geotechnical profession in New Zealand has definitely laid some good grounds for its future. 

CLOCKWISE FROM TOP LEFT: The Clyde dam group observing the test of the spillway gates carried out on the day; The Clyde Dam group inside the dam structure; The infamous slip joint that will enable the dam to move if the secondary River Channel fault ruptures in a Dunstan fault event; Macraes Mine – bus; Macraes Mine Fieldtrip Group at Deadmans Point Rockslide.


Above: Frasers pit is a huge 280m deep hole in schist bedrock, where very large active failures are managed through monitoring with slope radar.The portal for the underground portion of the mine is visible to the left.


Above: The mists parted for us to have a clear view down into the Frasers pit and slope failure (this drone image is from the day before)!


Above: We were extremely fortunate to be able to finish our bus trips by historic train from Hindon to Dunedin through the scenic Taieri Gorge. The train is a victim of Covid – indications are that we may have been on the penultimate trip before it is retired for good!

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