The measured data from instrumented dams offer an insight to civil technician on the internal movements of dams. They also offer an information on the safety and confidence in designing and constructing dams. However, no one can exactly understand the movement of dams merely measuring the data. We can predict a danger with periodic measurements and timely analysis of the data. In order to do that, the development of an efficient method to analyze the data is necessary. It is also necessary to collect the data automatically, and to accumulate database. Then, it can be able to properly evaluate the safety of earthdams by examining the movement and danger factors based on the data and hence to predict the movement in a future and to cope with the danger properly. In this research, we built a system which is capable of accumulating and plotting database. We also developed a safety evaluation method using the measured data and numerical analysis. This research is expected to improve a safety evaluation and analysis techniques for dam structures and to prevent accidents of large structures by systematic analysis.
