Minutes of Proceedings of the Institution of Civil Engineers Volume 122, PT. 4 (Paperback)

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. 1895 Excerpt: ...is then brought forward by the gantry and is adjusted in position. Other rings with air-tight joints are then bolted on to it until a column is built passing up through the " pig-sty" framing and above the staging to the greatest convenient height. The column is then carefully plumbed and secured in a vertical position by the framing and wedges. The tubing and concrete kentledge subsequently described is inserted as the building proceeds, and is completed so far as is necessary; after which, if possible, it is left for a short time to give the concrete time to set. When the column is ready for use, the air-lock is placed on the top of it and bolted with an air-tight joint to the upper flange of the topmost cylindrical ring, when the air-connections are made and sinking under pressure can begin. If the cylinders have to be pitched in water, the cutting-ring and a convenient number of other rings are put together i in the " pig-sty " above the water-level. The column thus constructed is carefully lowered and guided into its exact position, and completed as in the previous case, excepting that the tubing and loading are executed under pressure. When pitching a column in a strong current of water, it should be placed a few inches up-stream from its true position, and afterwards moved down by wedging. If placed out of position down stream its adjustment is difficult. To prevent the cylindrical column from being forced upwards by air-pressure, and to insure its descent as the sinking proceeds, it is loaded until it overcomes skinfriction and other resistance, whilst yet thoroughly under control so that it may be readily hung up when necessary. If the loading is insufficient, the column may be lifted with an increase of airpressure or may fail ...