Theo Hnat

Inside Mainmark: Learnings from the Christchurch earthquakes

With Theo Hnat, Technical Manager, Mainmark New Zealand

How long have you worked at Mainmark?

I began working with Mainmark in the summer of 2013 while in my third year of university, starting as a site engineer on the Christchurch Art Gallery re-levelling project.

In my first year at Mainmark, I gained valuable work experience managing everything from design tools to costing a range of residential and commercial projects. This is an important part of the role because, as engineers, we work to very precise technical specifications. I have since progressed to Technical Manager at Mainmark.

What do you enjoy most about your role at Mainmark?

I enjoy the fact that I’m not stuck in an office, which is a typical scenario for many engineering graduates. I also enjoy observing the changes that have occurred in the industry, particularly new innovations that have emerged since the Christchurch earthquakes, including the development of Mainmark’s new Liquefaction Mitigation solution that is cost effective and non-invasive. Mainmark has also been proactive in adapting to shifts within the industry from its initial focus on residential work to larger scale commercial and civil infrastructure projects. This allows Mainmark to demonstrate its breadth of experience and capabilities to solve a wide range of ground engineering challenges.

What inspired you to forge a career in ground engineering?

It was during my second year of university, where I was undertaking a Bachelor of Engineering at the University of Canterbury, when Christchurch was hit by the devastating 2011 earthquake. This event had an enormous influence on my decision to pursue a career in the specialist field of earthquake engineering, which is a combination of structural and geotechnical engineering disciplines. I’m currently undertaking a Master of Engineering (Earthquake Engineering) with a focus on soil-foundation-structure interaction. So technically I’m an earthquake engineer, not a ground engineer.

Are there any exciting advances being made in ground engineering?

Yes, there are. Recently, Mainmark supported a series of ground-breaking liquefaction mitigation research trials in the Christchurch Red Zone. These trials were conducted with partial funding from the EQC (Earthquake Commission) and MBIE (Ministry of Business Innovation and Employment).

The aim of these research trials was to determine whether resin injection could be used as a viable form of ground improvement for ground affected by liquefaction. Based on our past experience with the system, we speculated that this could be the case, but as with everything in the engineering industry, the theory has to stand up to scientific testing and scrutiny. It has been exciting to see that our system has been well-received in the engineering community.

What were the results from the Red Zone trials?

After four years of extensive testing, which began in 2013, an internationally peer reviewed report on our Resin Injection Ground Improvement Research Trials has been released which shows that resin injection can demonstrably improve the density and stiffness of ground, and therefore increases the resistance of soils to liquefaction. The full research report is now available on the New Zealand Geotechnical Society online library, and information is also included in the MBIE Module 5: Ground Improvement of Soils Prone to Liquefaction.

The results are very encouraging and an exciting advancement in earthquake engineering. Engineers now have an alternative and proven remediation solution to help reduce the liquefaction potential in structures that have been adversely affected by such effects. This solution can therefore increase the resilience of structures in future seismic events.

Are there any projects where Mainmark’s Liquefaction Mitigation solution has been used?

Yes several. Mainmark carried out ground improvement and re-levelling at the Northwood Supa Centa in Christchurch, a large retail complex that was suffering from liquefaction-induced settlement damage following the 2011-2012 Canterbury earthquakes. Mainmark applied its engineered Resin Injection solution beneath the buildings, which densified and stiffened the underlying soils to varied depths ranging from four to seven metres.

Significantly, this project was undertaken without disrupting the operational trading hours of the ‘big brand’ retail stores including a major supermarket. The ability to apply this solution to a busy retail environment without the need for the retail tenants to stop trading demonstrates the significant benefits a liquefaction mitigation solution can deliver to businesses in particular. The process, alongside further structural repairs, has resulted in the Supa Centre achieving a 100 per cent NBS (new building standard) rating.

Other completed projects include a number of residential homes in Christchurch that Mainmark has successfully delivered liquefaction mitigation via resin injection. The same technology was also used to increase the bearing capacity of a large retirement village in Christchurch where soil subsidence was identified as a serious hazard. Using our Resin Injection technology we were able to successfully meet the project specifications and stabilise the underlying soil, reducing the likelihood of further subsidence in the future.

What has been your career highlight to date?

Being heavily involved in the Red Zone trials was certainly a career highlight for me as it was exciting to be able to prove a theory. When it comes to engineering it is critical to have scientifically proven results to back up claims, so the Red Zone resin injection trials and the subsequent peer review report that supports resin injection technology is something that I’m delighted to be a part of. I’m particularly looking forward to helping Mainmark promote its Liquefaction Mitigation solution globally and use it in other earthquake affected regions.

Theo HnatTheo Hnat

Theo is a R&D and Technical Manager at Mainmark. Based in New Zealand, Theo’s responsibilities include research in new technologies in ground improvement and liquefaction mitigation, structural risk assessment of existing structures, design, and analysis.