Naval Drydock Construction

The increase in width and depth of graving docks, to keep pace with the ever-increasing size of ships to be served, has introduced many difficulties in drydock construction. Three stone docks, small by today's standards, provided for naval needs until almost 1890. Then for 30 years expansion took place, and twenty-four larger structures were added. These were built of timber, then of concrete backing with stone interior lining, and finally of concrete throughout. Today's drydocks are usually built of concrete although a few have walls made of earth-filled steel sheet-pile cells. Ground conditions dictate construction methods, allowing for full or partial hydrostatic uplift, as required. Recent improvements permit construction in the dry with the help of well points, as well as construction without unwatering, using tremie-placed concrete. These advances made possible phenomenal increases—thirty major naval drydocks, mostly built during World War II.