It has been recognized by the model tests that a method to decrease active earthpressure by applying the light-weight materials as backfilling is effective in static state, but the data on the vibration properties of light-weight materials subjected to earthquake motion have not been obtained at all. The vibration behavior of light-weight materials and the pressure acting on the wall due to the materials during vibration were investigated by the tests using a shaking table. Results of the tests are summerized as follows.
1.The stiffness of light-weight materials in water decrease more than that of sand and become more movable.
2.In dry state, the pressure acting on the wall during vibration due to light-weight materials is amaller than tnat due to sand.
3.In submerged state, there are any cases which the amplitude of pressure due to light-weight materials is larger than that due to sand, but in general the total pressure during vibration due to ligt-weight materials is smaller than that due to sand.