Søgning i bogen
Den bedste måde at søge i bogen er ved at downloade PDF'en og søge i den.
Derved får du fremhævet ordene visuelt direkte på billedet af siden.
Digitaliseret bog
Bogens tekst er maskinlæst, så der kan være en del fejl og mangler.
PIERHEADS, QUAYS, AND LANDING-STAGES.
'95
140,000 cubic feet of stone, bulking from 14 to 35 cubic feet a-piece, were
deposited and formed into a berme 10 feet in width, with a slope of 2 to 1.
In order to secure this stone-work in position, large blocks, containing
175 cubic feet each, were placed on top. The blocks were made of granite
fragments and cement mortar in the proportion of 1 to 3 ; they had a length
of 6 feet 6 inches, a width of 5 feet, and a height of 5 feet 6 inches, and they
weighed 12J tons.
Work proceeded on these lines from 1892 to 1894. A storm in
November 1894, however, once more wrecked the pierhead, destroying the
uncompleted berme and its covering. All burrs and blocks lying in less
than i feet 6 inches of water were dislodged, and some of them swept up
the slope.
Subsequent measures for the protection of the pierhead have been directed
to the consolidation and maintenance of the mound, but on somewhat
different lines, experience having indicated that the largest blocks formed the
best covering material. Thus, in addition to a large number of the smaller
blocks which served to fill up gaps and to provide a flat surface, in 1895
eleven blocks of 635 cubic feet, and in 1896 ten blocks of from 530 to
1(65 cubic feet, were bedded on the rubble work in concrete composed of
granite and cement mortar.
Yet these measures were attended by no better success than that of their
predecessors. The very largest blocks, weighing 120 tons, were sooner or
later dislodged by storms and driven down the slope. They were continually
restored, until finally, in November 1899, a gale wrought such serious havoc
that even the lower portion of the pierhead foundation was exposed and
partially withdrawn. As a consequence, the whole weight of the super
structure came to rest upon the piling and staging which had been erected
for pile-driving machines and rail-tracks during the construction of the mole
and which had been left buried in the mound.
The only plan now was to fill up the cavities, and this was done by means
of stones and sacks of concrete packed within a circumscribing ring of blocks
of 350 cubic feet, each set in a double row. But, before this work could be
completed, fresh disasters occurred. The blocks were disturbed, and some of
the rubble carried away, in November 1900. No satisfactory repairs could
be effected during the winter season, and in the following April a violent
westerly gale once more devastated the whole pierhead. The staging-piles
broke; the crack which had formed at the junction of the mole and pierhead
at the time of the initial destruction of the terrace, widened out on the
Xonr side? a wid? °f 4 feet 3 inches’and the Pærhead’ a ^ge mass of
20,660 cubic feet, aud having a weight of 1680 tons, was slewed on its axis
through 12 feet towards the sea, and left with its outer edge depressed to the
extent of 4 feet 4 inches. In this condition it rested upon a few projecting
peaks or the mound. 1 J 6
During these experiences, it was observed that a concrete block of 1553
cubic feet, which had been set on the deop-water side of the head, had not