Recently new design methods are highly requested for construction of port facilities. One of them is to introduce the limit state method and it needs the probabilistic study of outer forcre. Earth pressure is one of the most important factos of outer force. Another new method is related to reformation of old port facilities. To reform them, designers shall counter the technical problems as interaction among the existing and newly designed structures and soil between them.
　Model tests for studying dispersion characteristics of earth pressure and the earth pressure change because of the relative movement of the neighboring structures are done to solve these problems.
　Main conclusions are as follows:
1)The least coefficients of variation of earth pressure at rest and active state and passive state are 0.1.
2)It is important to know the way of relative movement of walls for estimating the earth pressure change due to relative movement of the neighboring walls.