Foundation of the turbine unit of a thermal power plant on a construction site made of thixotropic soils

Introduction. Thermal power plants in Russia are the leading power generating complexes in comparison with other complexes of energy industry and due to their independence from the location of the energy source, they are often located on sites characterized by soils with unsatisfactory properties. A relevant example from the practice of construction in St. Petersburg on a construction site with thixotropic soils is considered.Materials and methods. Construction and operation of objects on sites with thixotropic soils attracts the attention of researchers and practitioners by their dependence on the impact of static and dynamic loads. Different methods of foundation construction (pile, slab, etc.) were proposed. The pile foundation design for an additional turbine unit of a thermal power plant in St. Petersburg, including two slabs with vibration isolators, is considered as an alternative.Results. The conducted research has shown that the presence of vibration isolators provides an opportunity to regulate the height position of the system “turbine unit – foundation”, as well as almost completely eliminates the transmission of vibrations to the ground (pile) foundation and adjacent building structures, including existing buildings. The performed geotechnical modelling (model “unit – baseplate – pile foundation” (dynamic calculation of the baseplate and static calculation of the pile foundation) and model “unit – pile foundation” (dynamic and static calculations of the pile foundation)) with the help of Plaxis 3D software package showed that the vibration level on the bottom plate of the structure and on the pile heads is many times (40 times) less than the level of 2 mm/s, at which it is necessary to take into account the reduction of the bearing capacity of the base of both the foundation itself and the adjacent ones.Conclusions. Despite the advantages of the alternative variant in terms of cost and volume, the risks associated with the alternative design induce to favour the design variant adopted in the design documentation.

dynamic load, foundation, pile foundation, slab-and-pile foundation, thermal power plant, static load, thixotropic soil, vibration isolator