Concrete block walls. Consists of heavy precast mass concrete blocks. This type of construction is suitable where a rock foundation exists since differential settlement cannot easily be accommodated by this form of gravity wall. Blocks are placed vertically above each other.
L-walls. Stable due to their structural and soil weight, which rests on the horizontal part of the L-shaped structure. L-walls can be built in situ in dry conditions or prefabricated ex-situ and then brought to the waterside.
Concrete caissons. A pressurized chamber underneath the structure is created to keep the water out of this chamber. From this chamber, the soil under the structure can be removed. By carefully and evenly removing the soil from under the structure, it will submerge gradually until its final depth. During this process, verticality is monitored continuously, and the place where the soil is removed from under the structure is adjusted accordingly to maintain verticality. Concrete caissons consist of open‑topped cells prefabricated in the dry (on land, in a dry dock, or a floating dock), usually floated to their final location and then sunk into position on the seabed. Concrete caissons may be built in a wide variety of shapes, such as rectangular, circular, or cloverleaf. Caissons are usually limited to about 30 meters in width. They are usually designed so that, after sinking, the top is just above the low water level with due allowance for waves. The cells are filled, usually with sand and sometimes concrete or gravel. The superstructure may consist of a solid in-situ concrete capping or a reinforced concrete edge retaining wall, which is backfilled, and the top surfaced with concrete paving. Caissons, after filling, form self‑stable structures that can be used to support heavy construction equipment. Large caissons will generally need to be strengthened with internal walls.
