Effective methods for renovating operational ventilation shafts in the St. Petersburg metro

Background. Reducing the duration, labor intensity and cost of work during major repairs and reconstruction of mine ventilation shafts. Aim. Improvement of repair methods for strengthening and thermal insulation of mine ventilation shaft linings. Materials and Methods. The results of design-theoretical studies and experimental research on the physical model of the ventilation shaft section are presented. The efficiency of foam-glass concrete application for major repair and reconstruction of ventilation shafts is confirmed. It is experimentally proved that when using this technology the jacket body freezing does not occur, and the temperature at the contact of shaft construction and ground does not fall to the freezing point of water. Results. The implementation of the developed technology on the operating shaft of the ventilation shaft of the metro, including the installation of the temperature monitoring system, is described. The results of monitoring confirmed the declared characteristics of the material and construction. To increase the thermal insulation efficiency and the speed of construction of the structural and thermal insulation jacket, the reinforcing cage was replaced by dispersed reinforcement with fibre application. Conclusion. The developed structural and heat-insulating jacket on the basis of modified foam-glass concrete containing fibre is able to effectively protect the lining of ventilation shafts from freezing, ensuring their durability and safe operation.