Salto de Miranda. Trabajos de excavación de la galería

Abstract

The first article of this series was published in issue N.° 162 of «Informes de la Construccion», under the title «Salto de Miranda». The present article deals with the work of excavating the gallery. Modern practice requires that to do this type of work successfully the auxiliary material should be most carefully studied beforehand. N.° 164 of the this magazine has included a paper entitled «Recent progress in the auxiliary material for underground gallery excavation», summarising the most recent type of machinery now available in the market. Since the Grand Coulee Dam was built by the Bureau of Reclamation, where essentially new techniques were introduced, including minimum times for maximum progress, these new procedures and equipment have been generally adopted throughout the world. To this must be added the urgent and increasing demands for electric power, and the vast amounts of money involved in these hydroelectric projects, which explain the rapid adoption of automatic procedures in this kind of work. In this paper the author explains how, using the means available to him, he sought to coordinate the various constructional tasks, to get as near as possible to the most economic working cycle. Underground ventilation is an acute problem, and involves the safety of those working inside the tunnel. The author explains, in simple terms, how the theory of fluids and air circulation can affect the rational and practical solution of providing adequate air supply for the health and comfort of the underground worker. To attain this end, however, a considerable mechanical and economic investment is necessary.