Hydrothermal amelioration

HYDROTHERMAL AMELIORATION of the frozen rocks (EN: warm water amelioration; DE: Wasserwarmmelioration des Frostbodens; FR: amelioration thermique par l'eau des roches permafrost; ES: mejoramiento termico por agua de las rocas de congelacion; RU: водно-тепловая мелиорация) is the transformation of the composition, structure, status, and properties of the frozen rocks, using the regulation of the intensity and character for the processes of the heat exchange and moisture exchange.

The hydrothermal amelioration is used for the improvement of the effectiveness during the development of the deposits of the useful minerals at the dredging places, for the artificial thawing of the frozen rocks, and for the protection of the thawed rocks against the freezing, and also during the construction and operation of the underground mine shafts and mine workings under the complicated engineering-hydrogeological conditions, which are requiring the artificial freezing, within the industrial and civil construction industry. The cryo-geologic survey is the scientific-methodological basis for the hydrothermal amelioration.

The external heat exchange and moisture exchange are regulated using the transformation of the components of the radiation-heat balance of the daylight surface: the total incident and reflected short-wave radiation, the effective long-wave radiation, the heat exchange of the surface with the near-surface layer of air, and with the the underlying rocks, the consumption of the heat for the phase transitions, which are associated with the evaporation, condensation, sublimation, and desublimation of the moisture. The techniques for the thermal amelioration of the frozen rocks are the removal of the natural covers, the blackening of the surface, the covering of the surface with the films, which are translucent and slightly moisture permeable, and with the materials for the thermal insulation (polystyrene foams, snow, water-ice, air-ice, and other coverings), the construction of the wind barriers, canopies, and so on; these techniques are usually used for the comparatively large areas at the dredging places. The activities of the hydrothermal amelioration for the transformation of the composition and properties of the layer, which is ameliorated, are: the moistening, drying, and drainage of the rocks, the changing of the level of the ground waters, and of the regime of the freezing and thawing of the soils, their compaction and decompaction, the cementation, salination, and so on. They regulate the internal heat exchange and moisture exchange within the rocks on the account of the usage of the supplemental sources of the heat (the heat carriers are the water or steam, the air or gas, and the electric current). One of the widespread methods for the thawing of the frozen rocks at the dredging places, and during the thawing before the construction of the built structures, is the hydraulic thawing. They thaw the frozen rocks using the electric current with the low or high frequencies. The supply of the electric current is performed with the help of the electrodes, which are immersed into the frozen rock, and which are positioned at the distance of 2-6 metres one from another. The maximal depths of the thawing amount to 10-15 metres and more during 30-50 days.

This method of the hydrothermal amelioration is most usable for the thawing of the slightly-filtrating clayish rocks, when other techniques are less effective. The techniques of the hydrothermal amelioration, which are based on the cooling action of the aerial (gaseous) flow, are used for the artificial freezing, or for the decreasing of the negative temperature, of the soils of the foundations of the built structures, and of the soil walls of the underground mine shafts and mine workings, using the circulation of the cooling agent within the ventilating channels, within the freezing columns, and so on. The preparation of the air, which is cooled to the negative temperatures, is performed using the natural method (during the winter) or on the account of the usage of the cooling machines and various devices.