Geomaterials expert shakes up earthquake studies

12 September 2019

Professor Andrew Chan (Croucher Studentship 1982, Croucher Scholarship 1984) has spent nearly four decades studying the effects of tremors and tsunamis on the earth and buildings. And still the soil has many secrets yet to be uncovered.

Before Chan, many scientists only studied the solid aspects of construction: buildings and the soil underneath. “My computer program considered both the soil and the water together. I was the first to make it work efficiently and it has been adopted as the standard procedure in these kinds of analyses,” he said.

In 1990, he co-authored a journal article with his PhD supervisor on the subject of static and dynamic behaviour of geomaterials. It was an instant hit, with implications that reverberated through the scientific and construction communities. Nine years later, Chan’s team regrouped to write a book, Computational Geomechanics with Special Reference to Earthquake Engineering.

After graduating from the University of Hong Kong (HKU) with a bachelor’s degree of engineering in 1982, Chan completed his master’s degree at HKU and went on to do doctoral studies at the then University College of Swansea. His work focused on soil liquification and its impact on building structures.

Chan is now head of the School of Engineering at the University of Tasmania, where he continues his research.

“Soil liquification occurs when the ground shakes and becomes liquid,” he explained. “When we look at an earthquake, a lot of the time we think of the structural damage. But the ground actually causes most of the damage.”

Liquification was once a rare phenomenon for the foundation of human structures, but no longer. Humans are increasingly moulding the earth for their own purposes, and this carries serious risk. For instance, reclamation is a lengthy undertaking whereby tons of rocks and cement are poured on to the seabed. Soil is then layered on top.

In land-starved Hong Kong, the process of land reclamation has expanded natural shorelines and created entirely new ones. Approximately 25 per cent of Hong Kong’s developed areas – or 6 per cent of the city’s total land – has been reclaimed from the sea, according to the government’s Task Force on Land Supply.

But in the case of a natural disaster, Chan says that these areas would be vulnerable to liquification if the soil is not properly and fully consolidated. This happened to two artificial islands in the 1995 Kobe earthquake in Japan, and to an area of Christchurch in New Zealand in 2012.

“For example, if an earthquake happened in Hong Kong, the airport may be susceptible because the ground has not consolidated completely. The soil is not dense enough in ground that is geologically new or reclaimed, so liquification often happens.”

Hong Kong is not alone in its use of reclamation. Singapore and Macau both use the technique to expand their land – Macau’s land mass has grown 160 per cent. Outside Asia, land reclamation is equally common in marshy regions such as New Orleans and the Netherlands.

Chan’s research is key to keeping these areas safe, and according to him it is not all bad news.

“The good thing is that most modern buildings in cities are very tall and built on piles. Even if the ground is liquified, it may not hurt them,” he said.

In the case of Hong Kong, the risks of earthquake damage are further mitigated by the architecture employed. “People have done analysis to show that even if Hong Kong is hit by an earthquake, most buildings should survive,” he said. “This is because there are strong winds due to typhoons here and the buildings are built to withstand dynamic loading.”

Soil liquification helped Chan make his name in the scientific community, but he has since branched out. “It made me famous,” he acknowledged. “But the subject has now entered into an engineering phase. I stopped publishing in that area about five years ago.”

Chan’s latest interest is the finite discrete element method. In simple terms, this is a way of solving engineering problems by dividing a large system into smaller parts while allowing for discontinuous interactions.

“You basically divide the ground into squares or triangles,” he explained. “And then we analyse each of them. Recently, I have been specifically working on discrete particles. Instead of modelling continuous things, we model each particle separately.”

This work relies on digital tools and allows Chan to combine two of his passions. “I like computing, but I chose not to pursue it as a career,” he said. “In the end, though, my research is all about computing.”

His recent work has also included how modern miners are using explosives to dig deeper than ever below the earth’s surface.

Understanding how the exploded soil and rock will behave can mean the difference between life and death. “We look at explosions to see how they can be done carefully and safely,” he said. “We can also model how mines will collapse.”

Between working for the mines, doing research and teaching, Chan is always busy. The professor is a force of nature, much like the subject he has devoted his life to studying.

Professor Andrew Chan received a BSc (Eng) with first class honours from the Department of Civil Engineering, University of Hong Kong (HKU), in 1982, his MPhil from HKU in 1985, and his PhD from the Department of Civil Engineering, University College of Swansea (since renamed Swansea University), in 1989. Before joining the University of Tasmania in Australia as Professor and Head, School of Engineering and ICT, in March 2015, he was Professor of Civil Engineering and Deputy Dean, Information Technology & Engineering, at the University of Ballarat, Victoria. Prior to this, he held posts at the universities of Birmingham, Glasgow, and Cambridge, UK, among others. He is a Chartered Professional Engineer and registrant on the National Engineering Register, Engineering Executive, and Fellow of Engineers Australia. He is also a member of the British Computer Society, Chartered Engineer with the Engineering Council, a European Engineer with the European Federation of National Engineering Associations, and a Fellow of the Higher Education Academy. He was awarded a Croucher Scholarship in 1984 and a Croucher Studentship in 1982.

To view Professor Chan’s full Croucher profile, please click here