Development of "wedged caisson" as a quay wall structure and its application to Hidaka-port Japan

For the gravity type structures like the earthquake-resistant quay walls specially designed for emergency situation at severe seismic events, much severe seismic conditions are considered for the design and consequently the width of the caisson becomes large and ground improvement to support them also becomes large. Considering those situations, new type of quay wall structures named "Wedged caisson" was developed. The wedged caisson has the characteristics of high earthquake resistant capacity without an enormous increase in construction cost. The wedged caisson has a bottom that declines towards the land side. To find the suitable range of the bottom declination angle, a series of shaking table tests using 1/22 scale model caissons with bottom declinations of different angles were carried out. The tests were also simulated numerically using two dimensional effective stress analysis methods. From the results of the shake table tests and the effective-stress-based analysis method, it was found that seismic capacity of the slender wedged caisson with a bottom declination of 5 degree is comparable to that of the traditional caisson without any bottom declination. The developed wedged caissons were installed in Hidaka-port and reported current situation of the wedged caisson