In recent years, there has been increasing demand to reduce costs for public works in Japan. Correspondingly, great efforts have been directed toward using and upgrading existing infrastructures efficiently. In this context, our division has been studying methods for enhancement and improvement of existing port facilities.
Because the caisson-type quay wall (Figure 1) is one of the major types used in Japan, it is desirable that this type quay wall have more front-water depth to better accommodate the larger and larger vessels coming alongside. A method often employed for this improvement is to construct a new pier front onto the caisson-type quay wall as shown in Figure 2. It is impossible, however, to adopt this method for a caisson quay wall when there is not enough frontal space: thus, a new improvement method applicable to such situations is being developed. In the new method, a rubble mound beneath a caisson is solidified then cut to increase the front-water depth of the caisson as shown in Figure 3.

Our division is continuing to study with the aim of utilizing the technique.