The GEOASIA Research Society

Message from the Society President in 2016

  Counting from August 2006, when the GEOASIA Research Society was registered as a private organization, we can say (in August 2016) that it has reached its tenth birthday, making this Issue 10 of the Bulletin. But I wish to take this occasion of my tenth President’s Message to look a little way further back still. It may make my message a bit long, but I hope it can be forgiven.

  All of the basics for the underlying framework of the GEOASIA geotechnical analysis model were already in place in a doctoral thesis by Professor Toshihiro Noda, At the time a third-year doctoral student, with the (Japanese) title: “A Study on Behavior of Saturated Clay near/at Critical State and Soil-Water Coupled Finite Deformation Analysis.” This was in March 1994. In this paper, under the constraint of no volume change asserted in Darcy’s law, Noda, using an effective stress principle (for soil -water coupling), succeeded in substituting an incremental constitutive equation for elastoplasticity (the Cam-Clay model) into an equation for the equilibrium of incremental forces, thus opening a way to a flawless and exhaustive analysis of all conceivable non-static problems of normally consolidated clay from deformation to collapse, and also for post-collapse behaviors. This was achieved through a fusion of material and geometrical nonlinearities. Later the same year (1994), with the additional introduction of a subloading surface, an exhaustive analysis was made possible for all behaviors of overconsolidated clay. Having come so far so fast, no one would have been surprised if fundamental geotechnical research at Nagoya University had paused there for a while to take things more gently.

  But as it was, the Hanshin / Awaji area around Kobe was rudely hit on January 17, 1995 by the 1995 Southern Hyogo Prefecture Earthquake. At the sight of a major city in flames after a seismic shock that hit it from directly beneath, we could only stand and stare while the feeling sank in: Is this all that our past soil mechanics was worth? Defeatism was in the air: “Faced with a real earthquake, what was the point of it all?” But at the same time – this may have been a personal impression but it was what I felt – there seemed to be a surge of youthful energy taking hold of geotechnical research in Nagoya University and pushing for its renewal. With the new concept of the superloading surface, developed at the end of 1997, the crucial distinction between sand and clay soils seemed to have come clear to everyone in the research group, and from that point on, led by the work of Assistant Professor Noda (as he now was), the old formula of the equilibrium of forces came to be replaced by an equation of motion. Now all was ready at last, to use a metaphor, for the heavy tiller to be flung round, leaving Nagoya University’s geotechnical crew to sail off on their own bold course across wild but open seas bound for realms of dynamic problem solution. By 2005, just ten years on from the Hanshin / Awaji Earthquake catastrophe, they were in position to receive \50m in competitive research funding from the Ministry of Land, Infrastructure, Transport and Tourism with a proposal for seismic evaluations of manmade islands and coastal revetments constructed of intermediate sand/clay soils and for soil reinforcement technologies for the control of liquefaction and land slumps. The year after that saw the launch of the GEOASIA Research Society. All of the terms highlighted above in bold can be brought together in the descriptive formula from which the name GEOASIA derives: “All SOILS ALL ROUND ALL STATES GEO-ANALYSIS INTEGRATION.”

  Developments since then can be found summarized in detail in the ten issues of the GEOASIA Research Society Bulletin. From the contents, it is apparent how much further the results have gone in the ten years since the Society’s foundation than in the preceding decade from the 1995 Hanshin / Awaji Earthquake to 2005. For example:
① The development of an unsaturated earth / unsaturated foundation analysis based on the analysis of a three-phase system taking in air, water and soil skeleton,
② A further refinement of the constitutive equation of elastoplasticity through the inclusion of a combined loading surface,
③ An extension in the area of applicability for coupled analysis as a result of a full formulation.
④ 2-D and 3-D calculations of a surface wave and recreation of a long-frequency long-duration seismic movement of high intensity,
⑤ Inverse analysis of a strong seismic reading obtained from a non-linear surface-layer ground response and an estimate of the seismic movement that gave rise to it,
⑥ The development of a macro-element method capable of taking account of well resistance,
⑦ A seismic diagnosis based on the model analysis of an earth-built or similar structure.
These developments, along with others, were all achieved in our past two or three years of research, yet they all involve study objects and aspects of content that would have been unthinkable ten years ago, It is because these research attainments are all so reliable taken individually that each of them is able to function successfully as a springboard to the next. Thus one creation gives birth to another, generating a virtuous cycle that has sustained itself for over 10 years. Example ① above, the technology for unsaturated foundation analysis in a three-phase coupling system, which goes back to 2015, has become the object of a second patent providing new financial support for the GEOASIA Research Society along with the earlier first patent for the analysis tool designed for a two-phase water-soil system. Armed with this new analysis instrument, solutions can be expected not only for unsaturated levee and seawall problems along rivers and coasts but also for cases like that of a 90m high mudstone embankment carrying the New Tomei highway across wetland, a structure that is vulnerable to deterioration through slaking. The new analysis tool can show what behavior to expect from such a structure upon the occurrence of an earthquake.

  It has been widely supposed since the Hanshin / Awaji Earthquake that Japan is entering a distinctly active seismic phase. There are many seismologists and volcanologists who go so far as to say that “21st century Japan closely resembles the Japan that went through tectonic changes in the 9th century.” If we align the Great East Japan Pacific Offshore Earthquake of 2011 with the Jogan Tsunami and Earthquake of 869, maintaining the parallel we find that the 2020 Tokyo Olympics year matches up with the Sobo Musashi Earthquake of 878 (which struck from directly below present Tokyo), and that 2029 would correspond to 887, the year of the Ninna Earthquake (a connected triple occurrence of the Nankai Trough Earthquake). Even dismissing this formalistic way of superimposing today’s dates on past 9th century ones, an estimate based on “regularities in the active and quiescent phases of the Nankai Earthquake” would still indicate a high likelihood of a Nankai Trough Earthquake occurring
during the 2030s.
  Moreover, this periodic method of prediction tells us not only that this trough earthquake is likely to recur every 100 – 150 years, but also that there could be a longer cyclic pattern of 300 – 400 years (Ninna (M9) in 887; Shohei (M8.5) in 1361; Hoei (M8.6) in 1707) for a larger mega-earthquake, or indeed a connected chain of them. Following this alarming theory, the next connected mega-event would be due in the 21st century. It would seem that a Tokai Trough Earthquake, likely in chained occurrence, is due to precipitate a “Great West Japan Earthquake” and that there is no way of bypassing this fact.
The first blank question that calamity-struck residents will doubtless ask themselves after an event like that is the scientific one: “Why did this kind of ground liquefaction occur in my neighborhood?” In particular cases the victim may decide that it couldn’t be helped or that one thing or another was to blame, but before that, the starting point for facing and coming to terms with what has happened has to lie in a scientific comprehension of the phenomenon itself and its occurrence. In Bulletin no. 5 (“Message”), soon after the Great East Japan Earthquake, I wrote the same thing and said that unless an answer can be offered in proper scientific / mechanical terms, residents of places like Urayasu (which suffered widespread liquefaction) will never be convinced. When the Great West Japan Earthquake comes – as come it will – we can be certain that there will be even more widespread instances of phenomena that have never been seen before. As one who seeks the starting place for disaster prevention in hardware, I trust that the activities of the GEOASIA Research Society will have contributed substantially to the improvement of disaster response technology through the precautions taken in civil engineering work. I also truly hope that the GEOASIA Research Society can play a large part in supplying the hapless victims of the next disaster with the demanded facts when they most stand in need of a “scientific answer.”

  The Research Society is still facing numerous burdens and challenges as regards both the wider dissemination of the GEOASIA ground analysis technology and the need to train up human resources through the GEOASIA Master program. I take the opportunity of this celebratory tenth “Message” to ask all of our members for their continued support.

Akira Asaoka,
Senior research advisor, the Association for the Development of Earthquake Prediction (reg. foundation);
Emeritus professor, Nagoya University

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