Modern methods of cooling permafrost ground beds of multi-storey residential buildings

Abstract Introduction. The bearing capacity of soil in the frozen state is much higher than its bearing capacity at positive temperatures. Therefore, it makes sense to use frozen soil as the footing of a building in permafrost regions. However, the preservation of soil in the frozen state in a built-up area is a challenging engineering problem despite low average annual air temperatures (below –4 °C). Materials and methods. The co-authors employed numerical methods to study the temperature regime of the footing using TEMRA software. This software was developed at MISI – MGSU (State Registration Certificate 2016618937); it solves non-stationary thermophysical problems by the enthalpy method with regard for the phase transitions of the bound moisture in the temperature range. Results. Two approaches are used to preserve building footings in the frozen state: natural seasonal surface cooling and deep cooling, on the one hand, and reducing the thermal effect produced by the building on footing soils, on the other hand. In the first case, the surface under the building is cooled with air in the winter season using the cold ventilated space under the building, the so-called “ventilated basement”. Deep cooling is carried out using Seasonal Cooling Devices (SCD) that employs air-soil heat exchange with the help of pipes, filled with the heat transfer agent during the winter period. A change in the average annual air temperature inside the ventilated basement and seasonal insulation of its walls or the ground bed can reduce the thermal effect, produced by the building. Conclusions. The most effective way to keep ground beds of multi-storey residential buildings frozen is the thermal insulation of the footing surface in combination with deep liquid cooling devices.