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5 th Int. Workshop on Ice Caves (IWIC – V) Barzio (LC), Valsassina, Grigna and Milano, September 16 – 23, 2012 Volume of Abstracts climate condition of the outside world cannot save ice. It is external environment that cannot directly save the ice, thus, to reveal the mechanism of the ice preservation become a difficult scientific question. So far, several scholars have proposed their qualitative realizations. There are three opinions. (1) Due to negative geothermal gradient, the ice in cave could not be melted. (2) There is negative geothermal anomaly in the area, maintaining the ice. (3) Due to many factors, the ice in cave can be preserved. Both view (1) and view (2) emphasize that there is a „cold source‟ in the area. In this context, we focus on the outside temperature‟s influence with the internal temperature of the ice cave. We utilized Finite element method (FEM) to deal with the question. 2. The Principle of modeling - We consider two kinds of heat transfer mechanisms, that is, conduction and convection. In spring, summer or autumn, the external temperature is higher than the internal temperature of the ice cave. Air density increases in the direction of gravity. Thus, there is no convection. In this case, energy is transferred from outside world to the ice cave by conduction. In winter, the external temperature is lower than the internal temperature of the ice cave. The air density decreases in the direction of gravity. Thus, energy is transferred from the ice cave to inside world by convection. There are two points playing an important role in modeling. The one is that heat transfer efficiency of convection is much higher than the efficiency of conduction. Another point is that phase change processes are accompanied by either absorption or release of thermal energy. In the context, approximately, we consider the shape of the ice cave as a vertical tube. According to the experimental relationship of a vertical tube with natural convection, we determine the relationship between temperature difference and the Nusselt number. And then, we utilize Finite element method (FEM) to solve heat conduction equation. 3. Conclusion - We obtained the following three conclusions: (1) The ice cave can be maintained. The control factors are natural convection heat transfer and ice-water phase change. (2) In quasi-steady state, the ice cave temperature fluctuates in the range of (-3.9, -2.9)°C. (3) Without regard to air convective heat transfer, the ice in cave will all melt after 37 years. 21
5 th Int. Workshop on Ice Caves (IWIC – V) Barzio (LC), Valsassina, Grigna and Milano, September 16 – 23, 2012 Volume of Abstracts INVESTIGATION OF ICE THICKNESS IN THE URALS CAVES USING GEORADAR Stepanov Y.I. 1 , Kichigin A.V. 1 & Tainitsky A.A. 1 1 Mining Institute of Ural Branch of Russian Academy of Sciences, Russia (stepanov@mi-perm.ru) The staff of the Mining Institute has been studying caves of the Urals with perennial ice accumulations for some years. In February 2008, we used "Oko-M1" georadar to estimate the volume of such accumulations in the Kungur Ice Cave. The findings allowed us to estimate ice thickness and also develop the site model. Satisfactory experience of the georadar application enabled us to make conclusions about the possibility of more complete ice body geometry analysis in the Urals‟ caves with Ground Penetrating Radar. During 2010-2011 investigations in the Usvenskaya, Badyinskaya (Perm Region), Pobeda (Flying Dutchman glacier) and Askinskaya (Bashkortostan) Caves were carried out and the main geometrical characteristics of glaciers were studied. The most ice thickness variation is noted in the Pobeda Cave, from a few centimeters to 11 m (at dielectric permeability of ice ε=4). The glacier is characterized by a complex structure of bed with a ledge of about 4 m in height. The next in ice thickness is the Badyinskaya Ice Cave, where depth marks range from several centimeters to 4 m (at dielectric permeability of ice ε=3.5). In the Askinskaya Cave, ice thickness increases evenly from the distant part to its entrance from 0 to 0.5 m (at dielectric permeability of ice ε=4). Near the entrance we registered a sharp increase of “ice-rock” boundary depth in the form of clough that extends from entrance to the western wall (from 1.5 to 2 m) ending with a wall opening covered by a stalagmite. The maps of ice thickness and a 3-D glacier model were constructed based on the investigation as well as approximate volume of ice (without stalagmites ice) was estimated. In the Usvinskaya Cave, ice thickness is about 20 cm. Radagrams are characterized by poor quality that is caused by presence of numerous inclusions in the glacier body (rock fragments, wood garbage, etc.). Thus, the study gave information about ice body geometry in some Ural caves. 22
Page 2 and 3: IWIC - V 5 th INTERNATIONAL WORKSHO
Page 4: President 5 th Int. Workshop on Ice
Page 7 and 8: 5 th Int. Workshop on Ice Caves (IW
Page 13 and 14: Dear Participants, we are very plea
Page 46: POSTER PRESENTATIONS
Page 61: 5 th Int. Workshop on Ice Caves (IW

Volume of Abstracts - Università degli Studi di Milano

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