CONSTRUCTION TECHNIQUES AND COSTS FOR UNDERGROUND EMPLACEMENT OF NUCLEAR EXPLOSIVES

摘要

This report describes the equipment, methods, and costs that are considered applicable for underground emplacement construction of nuclear ex plosives such as would be used in nuclear excavation.nThe text of the report discusses the available methods and techniques currently being used in "big hole" (30-inch diameter and larger) drilling, tunneling, and conventional shafting. The technical data have been collected from the available literature as well as by personal contacts with the Govern ment agencies and private industries concerned.nBig hole drilling-'methods can be divided into four types: churn drilling, auger drilling, calyx drilling, and rotary drilling. Of these, auger drilling is the most economical for holes to depths of 200 feet in soft material, and rotary drilling is by far the best choice for depths in excess of 150 feet. Rotary drilling is not limited to any specific material type or hole size and therefore is the most adaptable method. Equipment for rotary drilling is variable, but in most cases consists of "beefed-up" oil well rigs employing modified hoisting facilities. The drill strings, drill bits, and circulating equipment are ordinarily designed specifically for big hole work. Typical input power ratings for the rigs range from 225 hp (drive-in rigs) to 1625 hp (stationary rigs), depending on the diameter and depth of hole. Borings from 36 to 72 inches in diameter are currently being drilled to depths exceeding 6000 feet with modified oil-well drilling equipment.