Many flexible anchorages of the sheet pile quaywall were damaged due to the recent earthquakes. It is considered because of lack of the suitable design method, but any effective method solving this problem has not yet been proposed.
　In the report the author revises the conventional calculation system, and proposes newly a design method of flexible anchorages during earthquakes, as follows,
(1) Proposes new foundamental equations for the lateral resistance of piles, which are easily analytical and practical.
(2) Correlates the resisting earth pressure and the coefficient of lateral soil reaction both for single piles and continuous walls on the basis of the new equations, and proposes practical values of the coefficient.
(3) Proposes a general equation of the lateral earth pressure during earthquakes, taking into account the cohesion and the adhesion between the clayey soil and the wall, for the purpose of calculating the above earth pressure for the coefficient of soil reaction.