Improvements to methods of producing foundations in deep water, especially for piersfor bridges

摘要

876,547. Piers. DUBOIS, L. J. June 22 1959, [July 12, 1958], No. 21354/59. Class 68(2). A bridge pier is constructed by building a column of open-ended reinforced concrete rings 1, 2, 2 and packing filling 8 into the internal cavity. The site for the first ring is prepared by scraping or jettising and the ring itself may have integral jets 18 (Fig. 10) fed through a conduit 19. When sedimentary matter has been removed from the site the ring is lifted and a rockfilling 20 introduced into the cavity thus created. When the foundation is satisfactory it is injected with grout. To prevent undermining of the piers, bituminous stove packing 40 is provided externally (not shown, see Fig. 7). When the first ring has been placed and filled, further rings are positioned with the aid of a guide system comprising guide cables 3, of which one is shown in Fig. 4, which are anchored at one end to the ring 1 and connected by sleeves 5 to the ring being placed. Each ring may also have guide arms to ensure the centring of each ring on the ring immeadiately below it. The pier is anchored to the foundation by bored piles 9 passing through the filling of one or more of the rings, into the bed rock. Pre-stressing of the pier is achieved by cables anchored in the rock and to the head of the pier and subsequently tensioned. When the top of the pier is above water it is capped with a concrete slab 10 which supports columns 12 which carry bridge spans 14. The pre-cast rings are brought to the site by floats and controlled during positioning from an artificial island standing on retractable legs. The rings may have internal remote-controlled floats which are filled and emptied pneumatically and can be detached from the ring when it is in position. In a modification the rings are of oval cross-section, formed by two adjacent rings joined by straight parallel webs.