Permafrost

distribution. Therefore it is necessary to study the mechanism of moisture-heat transfer. At
present most study on the characteristics of rock and soil engineering in cold region focus on
researching characteristics of frozen soil, the study which touch on rock especially soft rock is
rare; the study which deal with frost and thaw is rare. But as for rock and soil engineering in
cold regions, which coexist with rock mass and soil, deformation and strength property of rock
and soil show two sides from strength property of friction materials of melted rock and soil at
high temperatures to strength property of crystal lattice material of frozen rock and soil at low
temperatures under the freeze – thaw cycles condition or during freezing-thawing process. We
must therefore make an intensive study of moisture-heat transfer and phase transformation
under frost and thaw condition.
In this paper, the experiment study on the moisture and heat transfer of soft rock material
during its freezing and thawing is researched in the laboratory of our university. The soft rock
material-concrete mortar is used during the moisture and heat transfer experiment. Two
different kinds of soft rock material are experimented in the open system with temperature
gradients. On the ground of experimental results and analysis we can reach some conclusions:
the degree of the moisture and heat transfer is different between the different soft rock materials,
the content of quartz mineral in the sample is higher, the redistributing time of the temperature
field is longer; the gradient of temperature is the main driving power of the moisture transfer,
the grads is higher and the moisture field redistributes quicker; the porosity ratio is higher and
the process of freezing is longer.
Key words: freezing and thawing, moisture and heat transfer, the study of experiment
26
Artificial Freezing of Ground in the Base of Deformed
Buildings in the North of Siberia
Grebenets V.I. 1 , Titkov S.N. 2
(1. Lomonosov Moscow State University, Geographical faculty, Department of Cryolithology and Glaciology
box.ru; 2. Research Institute of Bases and Underground Structures, Ministry of Building of Russia)
Abstract: A problem of stability of buildings and structures in the permafrost zone has become essentially
aggravated during the last decade. In cities of Northern Russia the tendency to develop mass-scale
deformations of buildings and structures is observed. It was determined that the basic reasons of deformations
are negative technogenic impact on the geocryological and geoecological environment while global warming
has not shown detectable influence on the bearing capacity of frozen bases. A complex set of
engineering-technical measures intended to stabilize the situation in large industrial centers of the Russian
North as well as special methods for strengthening frozen bases has been developed and experimentally
proved in Russia. The emphasis is made on the application of artificial cooling through the tapping of natural
stocks of cold in rocks. Methods of cooling of boreholes by cold outer air by means of artificial and natural
convection as well as by the use of spending cooling agents have been developed. "Liquid" and
"steam-liquid" thermal piles demonstrated the most efficiency in operation. The positive as well as negative
experience of 20-years term of operation thermal piles have been analysed. Results of geothermal