Download or read book Ice Tunnel Closure Phenomena written by John F. Abel and published by . This book was released on 1961 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanics of closure, exhibited by ice tunnels, can be understood by considering the ice as a viscous solid. The viscous solid will flow, when subjected to a force, at a rate dependent on the magnitude of the force, the area of relief open for flow, and the apparent viscosity of the viscous solid. In the case of the ice tunnels, the force inducing the flow is the weight of the overburden; the area of relief open for flow is the tunnel opening; and apparent viscosity is the resistance to flow exhibited by the ice. The closure of a rectangular opening made in ice was measured. Maximum closure occurs at the center of unsupported roof, wall, or floor spans. The vertical closure rate decreases negligibly approximately 2% from the center of a room to approximately 6 ft from the wall. From the point about 6 ft from the wall to the wall, the closure rate decreases about 30%. Approximately 30% of vertical closure at the center of the span is due to flexure of the floor and roof. The remaining 70% is due to shortening of the wall height; the major portion of this wall closure occurs at the bottom of the wall. Over 80% of closure due to flexure of the floor and roof results from flexure of the floor. (Author).
Download or read book Permafrost Tunneling by a Continuous Mechanical Method written by George K. Swinzow and published by . This book was released on 1970 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: A mechanical method of tunneling in permafrost was investigated by excavating the Alaska Experimental Permafrost Tunnel in a perennially frozen stratum of Fairbanks silt at the edge of a gold dredge field 11 miles north of Fairbanks. The tunnel is 360 ft long and about 7 x 13 ft in cross section. It was cut by the Alkirk continuous cyclic mining method. Certain properties of the frozen silt were investigated and the tunnel was evaluated as a shelter for military purposes. Temperatures, mechanical compositions and moisture contents are discussed and observations on plastic deformation are given. The machine uses a pilot-pull principle to provide face pressure. Its potential performance was evaluated. Special observations of cutting strain and power consumption were performed and the cutting process was analyzed. It was found that the mechanical process is expedient and that with modifications the Alkirk principle promises to become a feasible method of excavating deep shelters in permafrost. Subsurface shelters in permafrost provide advantageous protection against high velocity shocks. The operations' efficiency is analyzed in the appendix.
Download or read book Under ice Mining Techniques written by John F. Abel and published by . This book was released on 1961 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods of excavating in the Greenland Ice Cap, and the planning required, equipment employed, and problems encountered are described individually for each of 5 operating seasons (1955-1959), and relative cost evaluations of the different methods are given. Three basic methods were used: hand-picking and manual haulage; explosives and manual haulage (drill-blast-muck cycle); and mechanized mining and haulage. Manual methods, which are of low capacity and limited to widths under 12 ft, are justified only when small openings are required, and in remote, inaccessible regions. The drill-blast-muck cycle of mining has a slightly higher capacity than manual methods, but requires power to operate the drills and to ventilate after blasting. Explosives can be used for room spans not exceeding 12 ft; when greater spans are excavated by blasting, the resulting roof is unstable. The machine method using mechanized coal mining equipment has the highest capacity and the lowest unit cost. Openings with roof spans in excess of 36 ft have been made with coal mining machines without dangerous roof conditions developing.
Download or read book When the Ice Is Gone What a Greenland Ice Core Reveals About Earth s Tumultuous History and Perilous Future written by Paul Bierman and published by W. W. Norton & Company. This book was released on 2024-08-20 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paul Bierman’s realization that Greenland’s ice sheet melted when Earth was no warmer than today sounds an alarm for our planet. In 2018, lumps of frozen soil, collected from the bottom of the world’s first deep ice core and lost for decades, reappeared in Denmark. When geologist Paul Bierman and his team first melted a piece of this unique material, they were shocked to find perfectly preserved leaves, twigs, and moss. That observation led them to a startling discovery: Greenland’s ice sheet had melted naturally before, about 400,000 years ago. The remote island’s ice was far more fragile than scientists had realized—unstable even without human interference. In When the Ice Is Gone, Bierman traces the story of this extraordinary finding, revealing how it radically changes our understanding of the Earth and its climate. A longtime researcher in Greenland, he begins with a brief history of the island, both human and geological, explaining how over the last century scientists have learned to read the historical record in ice, deciphering when volcanoes exploded and humans started driving cars fueled by leaded gasoline. For the origins of ice coring, Bierman brings us to Camp Century, a U.S. military base built inside Greenland’s ice sheet, where engineers first drilled through mile-thick ice and into the frozen soil beneath. Decades later, a few feet of that long-frozen earth would reveal its secrets—ancient warmth and melted ice. Changes in Greenland reverberate around the world, with ice melting high in the arctic affecting people everywhere. Bierman explores how losing Greenland’s ice will catalyze devastating events if we don’t change course and address climate change now.
Download or read book SIPRE Report written by and published by . This book was released on with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Library of Congress Subject Headings written by Library of Congress and published by . This book was released on 1992 with total page 1246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Library of Congress Subject Headings written by Library of Congress. Cataloging Policy and Support Office and published by . This book was released on 2007 with total page 1512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book USA CRREL Technical Publications written by Cold Regions Research and Engineering Laboratory (U.S.) and published by . This book was released on 1972 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Permafrost North American Contribution to The Second International Conference written by and published by National Academies. This book was released on 1973-01-01 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CRREL Technical Publications 1950 1975 written by Cold Regions Research and Engineering Laboratory (U.S.) and published by . This book was released on 1992 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Special Report Corps of Engineers U S Army Cold Regions Research and Engineering Laboratory written by Cold Regions Research and Engineering Laboratory (U.S.) and published by . This book was released on 1972 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hopping And Related Phenomena 5 Proceedings Of The 5th International Conference written by C J Adkins and published by World Scientific. This book was released on 1994-02-07 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomenon of hopping, in which a particle executes a series of jumps between discrete states, has a fundamental role in a wide range of solid state transport phenomena. In these proceedings acknowledged experts in the field describe important recent progress in developing the phenomenology of hopping processes and applying it to different systems, including crystalline and amorphous semiconductors, glasses, polymers, mesoscopic conductors and high temperature superconductors.
Download or read book Hearings written by United States. Congress. House. Committee on Appropriations and published by . This book was released on 1958 with total page 1550 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Department of the Army Appropriations for 1958 written by United States. Congress. House. Appropriations and published by . This book was released on 1957 with total page 2298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Department of the Army Appropriations for 1958 written by United States. Congress. House. Committee on Appropriations and published by . This book was released on 1957 with total page 1648 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rapid Excavation and Tunneling Conference 2013 Proceedings written by Michael A. DiPonio and published by SME. This book was released on 2013 with total page 1341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Every two years, industry leaders and practitioners from around the world gather at the Rapid Excavation and Tunneling Conference (RETC), the authoritative program for the tunneling profession. This comprehensive book includes more than 100 papers from industry experts, highlighting their most recent projects and sharing real-world experiences that will keep you up to date on the latest tunneling trends and technologies.
Download or read book Tunnel Lining Design Guide written by British Tunnelling Society and published by Thomas Telford. This book was released on 2004 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of geotechnical and geophysical -- pr) operies 160 -- 10.3 4 Design of tunnel linings 1 61 -- 10.4 Instrumentation of the CTRL North Downs Tunnel 164 -- 10.5 References 165 -- Appendix I Abbreviations and symbols 166 -- Appendix 2 Risk management 168 -- A2l Introduction 168 -- A2.2 Scope 168 -- A23 Risk register 169 -- A21. 1 When to use the risk register 169 -- A2.32 Whalt is it? 169 -- A2.3.3 Assessment process 169 -- A2.3.4 Key steps 169 -- A2.3.5 Risk assessment, qualitative or -- quantitative? 171 -- A2.3.6 R anaingt risk 175 -- A2.4 References 17.
