Experimental Study on Sliding Block Concept for Caisson Walls

Abstract

Two series of shake table tests were performed in order to study the sliding displacement of caisson type quay walls and breakwaters due to earthquake motions. In the first series of the experiments, a gravity type caisson wall was modeled and a horizontal tension force was applied. Then, 20 cycles of sinusoidal waves with different amplitudes were applied as input accelerations. In the second series of the experiments, three caisson type composite breakwaters were tested with different water levels. Earthquake records observed in Hachinohe and Ofunato ports were used as input motion. The results show that the yield acceleration at the time that sliding tends to start and during the sliding is not a constant value and the yield acceleration decreases immediately after sliding. Test results show that considering single yield acceleration during the displacement analysis may lead to erroneous results. The comparison of the test and analysis results suggests the use of two-level yield accelerations as static and dynamic levels. The outcomes of the test results also reveal the drastic effect of rocking on triggering the sliding.