Shipways with Cellular Walls on a Marl Foundation

Two full-length submerged shipways, whose walls consist of cellular cofferdams, are described in this paper. The cells of the cofferdams are filled with marl and founded on marl. The term “marl” is applied to a rather dense, greenish, calcareous sediment which has the grain-size characteristics of a fine, silty sand but, in an undisturbed state, the consistency of a stiff clay. The shipways are separated from each other by a partition wall which also consists of a cellular cofferdam. All the cells are of the diaphragm type. The hydrostatic uplift on the floors of the shipways is relieved not only by weep holes in the concrete mat but also, wherever necessary, by sand wells that drain the subsoil at a considerable depth below the floors.