In modern agriculture, the irrigation pipeline is an important infrastructure facility that forms the basis of technology in realizing advanced water management utilizing advanced technologies such as robot technology and information technology. However, in Japan, pipelines whose service life has exceeded 40 years have reached 2,600 km, and in fact, one fifth of the main pipeline has become obsolete. In recent years, 62% of the sudden accidents occurred at the state-run irrigation facilities was a breakage accident in the pipe canal. It is a polyvinyl chloride pipe (PVC) which is a pipe material used for about 30% of extension of irrigation pipeline. The accident that the PVC is broken is the largest among pipe breakage accidents, and it is still increasing. This is due to the fact that measures against fatigue failure were not applied in the conventional design method. Therefore, it is urgent to investigate the cause and develop countermeasure methods. We conducted monitoring inside the pipe and investigated the cause of fatigue failure. As a result, it became clear that the buried pipe exerts a large influence on the distortion of the pipe by the repeated load due to the water pressure fluctuation in the pipe rather than the road traffic load. Therefore, we are working on the development of an incidental facility that alleviates fluctuation of water pressure in the pipe, prevents pipe breakage due to fatigue fracture, and prolongs the life of the pipe. The mechanism is a simple structure combining an accumulator, an orifice, and a check valve. In the laboratory test, it was confirmed that the water pressure rise is reduced by 26%, and it can be expected to suppress the fatigue fracture of PVC pipe. Currently, we conduct demonstration tests on the site where pipe breakage is frequent.
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