Message from the Society President in 2017
At the 52th Japan National Conference on Geotechnical Engineering held at the Nagoya International Congress Center between July 12 and 14 this year (2017), members of the GEOASIA Research Society succeeded in presenting more than ten papers. These were highly diverse in their topics and contents, starting from subjects such as: ① An unsaturated soil analysis based on a 3-phase soil skeleton-water-air coupled analysis, ② An increase in software application scope thanks to a full (u-w-p) formulation of a soil skeleton-water coupled analysis, with its future perspectives, ③ Analysis of liquefaction and ground improvement by means of a constitutive equation of “combined loading elastoplasticity,” ④ A 2-D, 3-D calculation of surface waves and the reproduction of a long-period, long-duration strong seismic tremor, ⑤ Back-analysis of a seismic recording for a strong tremor in the case of a nonlinear surface-layer ground response, with an estimate of input vibration, ⑥ Shaking table experiment for a model saturated soil embankment slope, with particular regard to natural frequency and input vibration, …, …, and continuing on to: ⑨ Assessing the physical soil quality characteristics of earthquake debris and tsunami deposits, and ⑩ The relationship between slaking in crushed mudstone and grain diameter at the time of compaction, etc. Varied as they were, each one of these presentations provided a lively talking point for the conference and it was heartening to see the Society’s young researchers engaged so warmly in their discussions and responses. I was also struck by an astute question with which one of them challenged another presenter enquiring into something called “liquefaction probability”: “Liquefaction can’t just be a question of one or zero, something that happens or doesn’t happen. Doesn’t it include a whole dense range of varied complex phenomena between one and zero? How can you turn that into a 0 – 1 scale …?” Questions like this are a sign of the widening confidence now being placed in the GEOASIA approach and the GEOASIA Research Society, I felt.
Another noteworthy event this year, at the general Conference of the Japanese Geotechnical Society in June, was the Best Paper (English) award that went to authors Noda, Yamada, Nonaka, and Tashiro for their use of the GEOASIA software tool, functionally extended so as to take in a macro-element method, in a numerical analysis of the effectiveness of excess pore water pressure dissipation (EPWPD) as a precautionary measure against liquefaction. Awards are always welcome, whatever the occasion, but what especially impressed me here was the high quality of the article, subsequently included in the journal under the title “Receiving the Geotechnical Society’s Research Paper Award.” After describing EPWPD as a method, the paper adduced three reasons why problems of this type had previously defied analysis. Then it turned to the matter of whether a sandy soil was more likely to liquefy or consolidate and showed that this was a question demanding just the sort of seamless analysis that no tool except GEOASIA can provide, during the seismic event, naturally, but also afterward. The overwhelming superiority of GEOASIA to the two or three more traditional “specific programs for liquefaction” now in circulation was set out lucidly in a row of comparison points. The importance of this paper goes far beyond its straightforward case value as an application study for the macro-element method. The GEOASIA Research Society has already picked up a number of research paper awards of this kind, but among them all this is probably the paper that deserves the crown. It will be carried in the August 2017 issue, and I wish all of our members enjoyment in their reading of it.
Speaking of this great superiority of GEOASIA to more traditional “specific programs for liquefaction,” a paradox that seems to be arising lately, even as awareness of this superiority spreads and deepens, is a tendency in both engineering departments and the construction world, to regard GEOASIA and the GEOASIA Research Society as “inward-looking.” This is certainly not a description of the Society’s real attitude.
As the surest means of overcoming “inwardness,” our most pressing priority now is the creation of a Geomechanics textbook, of inspiring content, to prepare budding geotechnical specialists in GEOASIA Master or similar courses. What is needed in fact is a third revolution in geotechnical education texts to continue the impulse of the Cam-Clay approach that came to us from Taylor through Schofield and Wroth. In The Fundamentals of Soil Mechanics (1948), Taylor delivered the general summary of soil-type mechanics that had grown out of the work of Terzaghi. In Critical State Soil Mechanics (1968), Schofield and Wroth showed how this needed extending to take in the findings of elastoplastic theory. What fundamentally new element is required now, then, as the third advance in this revolutionary chain? Mere refinements of the elastoplastic constituent equation to allow for finite element methods, numerical computations, mixed soils and so on are not enough, taken singly, to warrant the use of a term like “revolution.” The time has come for a more heated discussion of how to combine all of these issues into one integral analysis: All Soils All States All Round Geo-analysis Integration.
This demand for a textbook is equaled, if not surpassed in urgency, by the issue of the long awaited release and diffusion of the GEOASIA program package itself. GEOASIA has its roots in a concern for “laying foundations.” A true foundation is not completed by “giving form and substance to a construction ground and then subjecting it to its own weight.” To take the instance of a river levee on an alluvial foundation, there are all kinds of diverse factors – the nature of the alluvial sediments, the structure of the levee, the dredging of the river course, to mention only some – that need to be attended to before an earthquake occurs. For our local port of Nagoya, we are currently engaged in calculations to track the loading history of shore defenses back to the (pre-1867) Edo period for use in a model reproducing the present-day state of the ground. Enhancing GEOASIA to the level of numerical operability required for work of this kind is no easy challenge, but we are making steady progress with it, as well as with all the other associated tasks of how to improve our pre-post processor, arrange elastoplastic ground data parameters into a single data bank, and so on. It will be worth the wait.
We are confident that the more chances engineering professionals have to put GEOASIA to the test, the more its latent potentials will blossom forth. All that remains for me to do otherwise is to appeal to all readers, especially to members of our Society, to give their constant support.
Senior research advisor, the Association for the Development of Earthquake Prediction (reg. foundation);
Emeritus professor, Nagoya University