Some Questions of Variability Physical Properties of The Rocks for Metro Ventilation Calculation
Between the ventilation air and the surrounding mining massif of the subway tunnels takes place simultaneous heat and hygroscopic mass transfer processes. Thermal-physical calculation of such objects is a significant engineering problem. The accuracy of the calculation determines the creation and preservation of a safe and comfortable underground environment for a large number of people. Thermo-physical and mass-physical characteristics of rocks, as well as the temperatures and mass transfer potentials fields experience variability and interaction each other in the surrounding mining massif. In this work, the noted interaction is investigated on the basis of the principle of Onsager reciprocity. On the basis of the experimental determinations performed, it can be noted that the thermo-physical properties are constants for the characteristic ranges of changing of temperature and mass (moisture) content of the surrounding rock massif. Mass-physical properties, on the contrary, significantly, change their numerical values for the same ranges by 300% and more, which indicates non-linearity of mass transfer processes in underground structures of the metro. The characteristic ranges of physical fields for the transport tunnels are: 275-323 K for temperature field and 2-12% for the moisture content field. The results presented in this work indicate that the thermo-physical calculation should be carried out in accordance with the identified new regularities. The article contains tables and graphs on the patterns of changes in the thermo-physical and mass-physical properties, depending on the physical fields of temperature and mass transfer potential in the surrounding mountain massif.
Keywords- Metro ventilation; Thermal calculation; Thermo-physical characteristics; Mass-physical characteristics