Foundations and Concrete Works

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1867 Excerpt: ...System of Construction mith Pierre Perdue, and the advantages resulting from the substitution of blocks of Beton for natural blocks. Piers of Pierre Perdue.--The system generally employed in our times for the construction of sea piers, is that known by the name of pierre perdue. It was practised by the ancients, as may be seen at the port of Civita Vecchia, which was constructed in the reign of Trajan. By the moderns it has been applied in various ways; the most remarkable instance is the Cherbourg Breakwater, which was begun in 1784. The materials used in the construction of these piers vary generally in bulk from 7 to 70 or 100 cubic feet; below this size they are shaken and overturned; but, according to the partizans of this mode of construction, this movement is only temporary, and the action of the waves working on the mass gives the latter a definite slope, at which it becomes capable of resisting the heaviest seas. This slope is a double one, the upper slope varying from-to--, and the lower from-to--. The depth at 6 10. 1 H which the change of inclination takes place varies from 13 to 16 ft. under low-water mark, according to the varying force of the sea in different localities. It is generally admitted, that below this depth the sea is not agitated, and that the change of slope is caused by this fact. Nevertheless, it must be acknowledged that the motion only diminishes, and never entirety ceases. A great number of wellknown facts prove that the sea exerts great force at depths of 32, and even of 65 feet below the surface. In stormy weather the waters become turbid, to a certain distance from shore, in consequence of the action of the waves on the bottom of the sea, an action sufficiently strong to detach seaweed and madrepores, which are thrown upo...