But a lot of slopes along railways have been covered by protection works, so evaluation of slope protection effect against rainfall is an important thing. Now we are carrying out rainfall tests using a model slope and a numerical simulation to get the basic performance of slope protection works. Further we are making clear the performance of concrete-frame. We think, by taking these results into account in the new slope estimation method, more precise estimation of slope will be make possible. We continue to research various subjects in the field of slope disaster reduction.
Major subjects taken up are as follows.
More economical and effective slope protection work is expected to reduce slope failures and rockfalls. We are studying the applicability in Japan of flexible rockfall protection barriers using ring nets, which were developed in Europe. Development of more adequate rainfall index for operation control Slope failure is induced not only by a rainfall at present but also by an antecedent rainfall. So in Japan aerial photographs taken by airplane or helicopter have been used to grasp the conditions of slopes and their surroundings. With further progress in this traditional method we have proposed a new method for the extraction of a slope at which the collapse is likely to happen.