Port economics

Bibliographic data

Monograph

Identifikator:: 173564191X

URN:: urn:nbn:de:zbw-retromon-111718

Document type:: Monograph

Author:: Cunningham, Brysson http://d-nb.info/gnd/1055472266

Title:: Port economics

Place of publication:: London [usw.]

Publisher:: Pitman

Year of publication:: 1926

Scope:: IX, 134 S

Digitisation:: 2020

Collection:: Economics Books

Usage license:: Get license information via the feedback formular.

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Chapter I. Ports and harbours

Collection:: Economics Books

PORTS AND HARBOURS ae this dispersive action calls for constant répleni hment or 72 material. Moreover, the depth of wave a eatin! Lad down to more than 30 ft. below sea leve \ “locks have been disturbed at a depth of 36 ft. Bel “thus levelp. mounds appear to be fairly stable and will star itl side slopes of 45 degrees or thereabouts. The wall reflects waves without breaking them, and is much less liable to damage. In a properly constructed work, maintenance costs are insignificant. The wall is more costly to construct, except, possibly, in relatively shallow situations, where the depth does not exceed, say, 4o ft. It is more effective than a mound, in that wave undulations, which are transmitted in a modified degree through the interstices of a mound, are completely destroyed against the face of the wall. For depths greater than 40 or 45 ft., it is economical and usual to employ breakwaters of the composite form, viz., a mound from the sea bottom up to a level of about 40 ft. below the surface, with a wall superstructure there- from to the summit. The convenience and economy arising out of the use of concrete has caused its almost universal adoption for breakwater construction, certainly in the case of the wall type; and a very suitable form is the monolith, or mass block. This is a hollow shell, generally rectangular or box-shape, built on land and launched, floated into position and sunk, thereafter being filled with concrete, so as to form a solid block of immense size extending from the foundation to surface level. The force required to disturb such a gigantic homogeneous structure would obviously be enormous. Other forms of breakwater construction consist of sackwork, in which jute sacks are filled with concrete and deposited under water by divers; cribwork, in which rectangular crates, or cribs of timber, are floated out into position, weighted with stone, and sunk (this is, of course, a type only suitable in cases of minor importance and is 2—(6010)

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