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Title: Ice tunnel closure phenomena
Authors: Abel, John F.
Keywords: Ice
Ice tunnels
Ice tunneling
Ice excavation
Ice tunnel closure
Glacier ice
Underground construction
Publisher: U.S. Army Snow, Ice, and Permafrost Research Establishment.
Series/Report no.: SIPRE report ; 74.
Description: Technical Report
Summary: 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 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 has been measured: 1.) Maximum closure occurs .at the center of unsupported roof, wall, or floor spans. 2.) 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%. 3.) 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. 4.) Over 80% of closure due to flexure of the floor and roof results from flexure of the floor. The maximum closure rates can be predicted empirically with reasonable accuracy. Equations were developed and are provided in this report. Glacial origin of the ice is assumed.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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