A system for constructing underwater impermeable protective sheathings of hydraulic structures or parts of them. At least one reference line is provided on the surface area to be protected and a protective sheathing is constructed underwater by positioning and stretching impermeable sheet materials over the area, keeping one lateral edge of each sheet material parallely aligned to said reference line, and maintaining hydrostatic balanced conditions between the pressures on the front and rear faces of each sheet material; the sheets are afterwards watertight connected along their edges and anchored to the surface of the hydraulic structure by mechanical anchorage devices.

The side of a hydraulic structure in contact with the water is covered with an impermeable membrane consisting of series of plastics so-called GEOSELLS which feature scales. These are interlocked with each other and then welded together edge to edge, and fixed to the structure by vertical fixings allowing movement of the GEOSELLS. This also favors drainage and initiation of microfissures regularly distributed in the structure. A granular coating is applied to the external surface at a raised temperature. This method is particularly suited to sealing granular rubble structures with or without binder. In rigid structures the binder may be a cement or a cement derivative, possibly a resin ("roller compacted concrete"). In flexible structures the binder may be a resin or a textile with or without reinforcing elements.

Watertight wall for a dam or a dyke, composed of a plurality of horizontal layers of compacted earth-fillings, the wall comprising a rear wall which is composed of prefabricated panels of height equal to the height of several layers, each panel being equipped with buttresses situated at the back of the panels, which buttresses are embedded in the embankment of earth-fillings and are equipped wiht draining pipes, the wall further comprising a continuous sealing layer which is cast against the front face of the prefabricated panels.

Method and apparatus for making a dock or seawall. A forming float device, comprising a forming deck and ballasting means therebelow, floats in a body of water a selected distance from the shoreline. A first wall section is formed on the top surface of the forming deck, such that the first wall section rests horizontally on the surface of the deck, and comprises a plurality of wall pieces whereby the wall pieces are aligned and shaped appropriately to together provide a uniform wall. Each wall piece is fastened by fastening means to the top surface of the forming deck. Earth reinforcing strips are installed in each wall piece such that the earth reinforcing strips extend upwardly from the wall pieces generally perpendicular to the planes defined by the wall section and forming deck and the earth reinforcing strips are secured in that upward position. Alternatively, a bundle of cylindrical containers may be attached together and to the wall section. The forming float device is rotated 90.degree. by means of ballasting means so that the wall section assumes a generally perpendicular position and the wall section is then rested on a pre-selected location of the floor of the body of water. Backfill is placed between the shoreline and the wall section such that the earth reinforcing strips and wall pieces are made to stabilize and maintain position. (Or, if cylinders are used, backfill is placed in and around the cylinders.) The forming float device is then freed from the wall section by unfastening the fastening means. Finally, the forming float device is rotated to its original orientation and refloated to the surface of the water by means of the ballasting means. The foregoing steps are repeated for each successive wall section to comprise the dock or sea wall and each successive wall section is positioned on the floor of the body of water adjacent to the previously placed section.

A roller compacted concrete (RCC) dam is formed from inverted T-shape face panels to produce a lower sloped profile and L-shape face panel to produce an upper vertical profile. The face panels have drain openings in their penetrating legs to communicate with drain fill lifts placed against the vertical rise of the face panels. RCC lifts are placed on the penetrating legs to lock the placement of these face panels. The drain openings provide terminal drainage for lift line seepage. The inverted T-shape face panel has both a protruding leg and a penetrating leg projecting into the RCC lift. The protruding leg is provided with a dowel for gripping and alignment that permits raising and lowering of the face panel and is received within a sleeve in the face panel therebelow.