FOUNDATIONS OF NEW BRIDGE

Press, Volume LXXXIX, Issue 27010, 9 April 1953, Page 8

FOUNDATIONS OF NEW BRIDGE

FRENCH EQUIPMENT? TO BE USED ADVANTAGES CLAIMED FOR MACHINE A . . Fren< * . boring and tubing machine, which has been extensively used overseas in building the foundations for wharves, bridges, and buildings and in boring for water, will shortly be used for the first time in New Zealand by the Ministry of Works m the construction of piers for a bridge across the Hope river, on the Lewis Pass highway. Two French foundation specialists from the • firm which makes the machine are now visiting Christchurch to supervise its initial operation and to train New Zealanders in its use. The machine is now at the southern plant depot of the Ministry of Works at Sockburn, where it will be tested early next week.

The Frenchmen are Messrs A. M. Picout and Joseph Dejeunes, of Baris. With them in Christchurch is Mr A. Maud, managing director of the New Zealand agents for the equipment. The machine is claimed to reduce veiy greatly the time taken to build foundations and, because of its ability to penetrate varying types of strata, including - rock, to make possible a more durable and solid foundation than would be constructed by other means. The machine is said to be capable of boring shafts between 14 inches and 60 inches in diameter through all soils and to depths up to 330 feet. It has been used in the reconstruction of har'bour works at Le Havre, and in Marseilles it was employed to build the foundation piers for a big commercial building. Boring Procedure The machine enables boring tubes to be made from flat plates, which are bent to the desired diameter and arc-welded. The first tube has a special cutting lip welded to it. A clamping collar attached to a 22-feet long arm is placed round the tube, and the arm, which is operated hydraulically, moves it backwards and forwards. At the same time a hammer grab, attached to a winch, drops into the tube and with its special jaws grabs material and extracts it from the tube. An oscillating arm throws the grab clear of the pipe and a piston inside the grab forces the material out.

As the tubing penetrates into the earth, additional lengths of pipe are welded on to it, and the clamping collar is moved to the top of the new section. When the required depth has been reached, steel reinforcing is placed in the tube and the concrete is poured. As the concrete is poured, the tubing is extracted and cut off in sections. The equipment is fully mobile. In Milan, a 247-foot well with a diameter of 38 inches was sunk in 86 hours, and the tubing was extracted in 42 hours.