Seepage of fill dams fluctuate due to rainfall and reservoir water level. To determine the stability of a dam, it is general, comparing the seepage on the same reservoir water level and effect of rainfall is small. However, the method thereof, it is difficult to determine the safety during rainfall and after the rainfall. There is a problem that cannot be constantly monitored. The authors analyzed the seepage caused by rainfall and reservoir water level. As a result, authors showed the normal range of the seepage without effect of rainfall. Further, based on seepage data during rainfall, consider representative of the effects of rain by a simple empirical equation form, it was investigated a method that can continuously monitor the influence of rainfall. Using these results, an actual dam was monitored and confirmed to be suitable for safety evaluation of fill dam.

The deterioration of the construction joint is an aging phenomenon of the concrete dam. This deterioration may affect the stability of the dam body. The investigation by a boring survey is a general method of verifying the deterioration of the construction joint in the dam body. But the investigation by a boring survey has several problems. In order to solve this problem, we have devised the method for estimating the state of the construction joint by using the results of the investigation by the impact elastic wave method. We have estimated the state of construction joint by focusing on the transmission and reflection characteristics of the elastic wave in deteriorated surface. By using this non-destructive investigated method, we were able to ascertain the deterioration area of construction joint in the concrete dam body.

Few records are available internationally concerning arch dams hit by large-scale earthquakes. Many of the behavioral and damping characteristics of arch dams under strong seismic motion are not clearly known. To clarify the three-dimensional behavioral characteristics of an arch dam under seismic motion, this study analyzed the records of the A Dam, which is controlled by the Japan Water Agency. The records include micro-tremor records obtained by simultaneous multipoint measurement (at 14 locations), small-earthquake measurements obtained by seismographs placed three-dimensionally (at 6 locations), and seismic records obtained at the time of the greatest aftershock of Niigata Prefecture Chuetsu Earthquake. Based on this analysis, we determined the character frequency of the arch dam (A Dam) under seismic motion. We also accurately reconstructed the behavioral characteristics of A Dam at the time of the greatest aftershock (a magnitude of 6.5) of Chuetsu Earthquake, by means of the three-dimensional finite element method (FEM) analysis that used an improved method of coupling between the bedrock, the dam body, and reservoir. Further, based on the reconstruction analysis results, we determined the damping coefficient for the body of A Dam, and using the coefficient we conduct dynamic analysis for level 2 seismic motion.

“IKIMONO-NOTE” is an advanced system for monitoring ecosystem and nature conditions using cloud-server computing and tablet computers. The system records photographs of plants and animals attached with GPS data at the site. Moreover, the system offers communication platform between construction staffs and research engineers through the cloud computing network. The engineer can give accurate advices for the ecosystem preservation to the construction staff on time, and construction process was able to run smoothly. The monitoring system contributes effective means for ecosystem preservation at the construction site.

The safety of overturning of concrete gravity dams is considered theoretically in their structure design. The difference between no tensile stress in upstream face and middle third requirement is studied. The new idea of safety factor for overturning is proposed.