抄録
In a designing of the most of Portal Rigid-frame Bridges (PRB), the earth pressure by the backfill soil for abutment is taken into account as one of design advantages. Accordingly, the soil in the backfill has to be hold in a good condition to show a proper pressure. However, generally, the soil is under an undesirable state due to the water penetration by rain water mainly and also there are few study results regarding these problems. The survey and analysis for the drainage method in Japan, USA and European countries are carried out and a desirable method is proposed in this paper. The usefulness of proposed method is confirmed by two dimensional water penetration analysis using the software PLAXIS.
