In prepearation...
In our laboratory, we make use of the underground aiming to contribute with countermeasures for environment problems, resource problems and disasters. In order to deal with problems that are complex and sometimes difficult to directly observe, we do research by integrating several approaches, such as theory, simulations, laboratory experiments and field research.
Groundwater is an important water resource because of its low cost and comparatively stable quality and temperature, but one of its drawbacks of using it is the subsidence problem. In Japan, it was a big social issue and one of the major public nuisance. In the actuality, it still continues in some regions and it is becoming a serious problem in the metropolitan areas located in the coastal plains in various countries in Asia. By considering appropriate ways to use the ground water, we do numerical simulation and other techniques aiming to contribute in the decision making related to maintaining a balance between the increasing water demand due to industrial expansion and environmental concerns.
The observation of the deformation of the bedrock during the construction of underground architectural structures or structures that serve as foundations of buildings is extremely important to evaluate the safety and soundness. In the future it might also contribute to the prevention of earthquake disasters. In this moment, we are performing long period demonstration tests of a technique that can measure the deformation of the bedrock with an ultra high precision (about 10-8ε or better) comparable to the worldfs top level, to evaluate the observed data through numerical analysis and experiments.
The underground, which maintains a stable temperature through the year, can be used as the destination of the heat transferred by heat pump air conditioning. This ggeothermal heath, which improves efficiency much, is expected to be the peak cut technology of the energy saving technologies, and is actually introduced greatly in Europe and America. But, in Japan it could be said that it hasnft spread at all. The avoidance of the risks and costs due to the complexity of the stratum and groundwater flow, and excavation costs are thought to be major causes. Also, there are many regions that have groundwater pumping regulations in order to prevent subsidence, which restrict the use of water pumping/injection methods for an efficient heat exchange. We are developing modeling techniques and doing experiments of Heat transport/Groundwater flow/Ground deformation coupled phenomenon to reduce these costs and risks, and also to reduce the probability of ground deformation or underground temperature change.
The observed data is a record of the reality, but observation has its limits such as measurement range or measurement errors depending on the used technique. On the other hand, mathematical models are correct in theory, but it canft reproduce processes that haven't been taken into consideration and also has uncertainty of the parameters, therefore this one is also not necessarily correct. Alone they have their own limits as mentioned above, but if they are fused together in order complement their weaknesses and enhance their strengths, it might be possible to estimate the most plausible actual condition, or to increase the precision of future predictions. We are doing research on improving the concept of data assimilation and inversion analysis by incorporating them, and on methods of getting the most out of physical models and observed data.