Message from the Society President in 2015
For the October 2015 special issue of the journal of the Japanese Geotechnical Society, focusing on the theme “Recent Trends in Seismic Response Analysis,” several members of our research society under Professor Toshihiro Noda have authored an article illustrating the use of the GEOASIA analysis method. It is now nine years since the launching of the GEOASIA Research Society as an incorporated association pursuing activities for the dissemination of the GEOASIA geo-analysiscode, and at least as a name, GEOASIA is by now fairly well known in industrial, administrative and academic circles. That much is clear from the fact that an article like this was requested for the special issue in the first place. Naturally, the merits of GEOASIA were already sufficiently well recognized before. Awards from a number of academic societies, and certificates from the Minister of Education and Science, had cemented its reputation as “a systematic research for the clarification of both static and dynamic ground responses based on elastoplastic mechanics.” All of these practical results and technical attestations supply welcome and valuable support when it comes to dissemination work. But when all is said and done, a pioneer developer is not often offered this sort of chance of an “official” platform from which to demonstrate the capabilities of a tool such as the GEOASIA geo-analysiscode. As the article in the October special issue is easy to follow and appropriate in its content matter, allow me the liberty of citing a few parts of it here.
“With previous geo-analysis codes, the choice of which code to use involved a prior decision of what was to happen in the ground. Codes were use-specific, so to speak, even for analyses of the same ground, there would be different codes and different input data for soil characteristics depending on the kind of engineering problem being tackled. ( … ) In the case of a ground made up of alternate layers of sand and clay, the ground consolidation behavior would be calculated by treating the sand as an elastic body and using a specific static consolidation code for the clay, whereas for behavior in the event of an earthquake the clay would need to be treated as elastic while using a specific liquefaction code for the sand.” (…) “In order to create a new geomechanics that allows us to get away from this ‘moment by moment’ view of responses, our aim was first to give the soil constants and initial conditions for the ground and then, once this is achieved, to develop an analysis code capable of showing what will happen in a ground of this kind in response to such or such a pattern of external forces.” To make all of this possible, “we developed GEOASIA , an integral analysis code offering a unified framework to account for mechanical behaviors in all categories of soils ranging from sand to clay through all the myriad gradations between (ALL SOILS), under the proposed control of an elastoplastic constitutive equation (the SYS Cam-clay model) ( … ) based on a finite deformation theory applicable to all deformation and breakdown problems without distinction (ALL STATES), and, as a crowning advantage, it had to be usable in static and dynamic problems alike once allowance has been made for inertial force responses (ALL ROUND).” Most recently, “the code (is no longer) restricted in its scope of analysis to saturated soils ( … ) but its capabilities are being extended to deal with coupled three-phase (air-water-soil) analysis problems in which the distinction between unsaturated and saturated soil states falls away.”
As I already noted in my Message last year, this latest development of unsaturated soil analysis, along with the greater intricacy introduced into the elastoplastic constitutive equation by considerations such as hyperelasticity and the combined loading surface, are currently bringing about rapid gains in versatility for GEOASIA . At the end of the article in the special issue, the following points are made about the precision of the GEOASIA analysis:
“In addition to the inevitable non-uniformity of the ground in any actual site, other practical problems include high degrees of uncertainty over what kind of seismic wave to input as an external force, and the further difficulty that many mechanical phenomena that are really 3-dimensional can only be represented in a stand-in way as 2-dimensional problems. Naturally, this places limits on accuracy. There is no point in getting too excited about small “quantitative” differences of a few tens of centimeters lost or gained. At present, the best we can aim for ( … ) is an analysis code of the kind that can supply sample concrete answers to “qualitative” problems and thus show, with respect to any assumed set of external force data, what series of events will occur in the ground affected and whether some design oversight might not need seeing to.” As for the present concern for dynamic problems involving external seismic forces and the like, the question to ask here is whether these are really being sampled appropriately.
In the same special issue last October, in addition to the article by Professor Noda and his collaborators there was another based on the case of an actual river embankment. It was by Professor Takeshi Kodaka and Society member Takahiro Yoshikawa ( GEOASIA Master) and involved the calculation of a seismic response in an unsaturated soil.
As is clear from the instances above, refinements are proceeding steadily in the development of the GEOASIA geo-analysis code. But this is also becoming ever more apparent through the expansion of the GEOASIA Master program. Of five very recent GEOASIA Master awards up to 2015, three went to students finishing graduate school courses: Toshiki Fukunaga in 2013, and then Kenta Kato and Takahiko Goto in 2014. All three of them made distinguished contributions to the refinement of the GEOASIA code either in developing new applications, e.g., for mutual interactions within combined ground and structure systems at the time of an earthquake occurrence, or for the behavior of unsaturated soils, or, more methodologically, in the enhanced “visibilization” of dynamic nonlinear problems using progressive linear approximations. Previously, there seemed to be a sense of the GEOASIA Master program being confined to doctorate candidates, but seeing it beginning to spread like this outside of those earlier bounds is a gratifying sign of the greater diffusion of the GEOASIA geo-analysis code. So far, the growth has not spread outside of the research laboratories of Nagoya University, but what we are now seeing for GEOASIA may be the birth stages of a wider advance into educational technology, as a new approach to geomechanics. Last but not least, March 2015 saw the appointment of Toshihiro Takaine, our first ever GEOASIA Master, as (full-time) assistant administrator of the Research Society office. I am sure that this, too, will be of great significance for the further expansion of GEOASIA . Hopefully, a result, GEOASIA will seem closer at hand, and more accessible, to many Society members.
Next year, 2016, will mark the tenth anniversary of the Society’s foundation. Let us concentrate our efforts in the remaining year up until then so as to be able to report to our members the realization of some of our longstanding ambitions such as the preparation for press of a GEOASIA textbook, the release and sale of a diffusion edition of the GEOASIA geoanalysis code, the opening of a Tokyo office for the GEOASIA Research Society, to name just a few.
A closing word: Readers will probably have heard of the sad loss of Professor Minoru Matsuo on May 9, 2015. In common with many of the academic staff belonging to the Society, I remember him as a cherished teacher. The July issue of the Japanese Geotechnical Society journal included an obituary article. I hope that members will read it and savor the pleasure of a trip back to old times.
Senior research advisor, the Association for the Development of Earthquake Prediction (reg. foundation);
Emeritus professor, Nagoya University