Theoretical substantiation of the layout decisions of station complexes of the underground of medium depth (up to 40 m) in the engineering and geological conditions of Saint Petersburg

Abstract

The development of a modern city and the increase in the occupied territory also involves the improvement of its transport infrastructure. In accordance with the sectoral scheme of development of the subway of St. Petersburg and the current backlog of its implementation requires a new approach to the implementation of the plan for the construction of the subway network. This article proposes the concept of space-planning, structural and construction solutions for metro stations of the ring line, as well as for the peripheral areas of the city. Over the past 10 years, there has been a rapid increase in population and active high-rise development of all areas of the city, increasing congestion of both urban and suburban roads, which leads to inefficiency of public and individual transport. For a long time there has been a problem of unloading the existing subway lines and exceeding the uncovered areas by available types of urban passenger transport, the main of which is the subway. To meet the needs of the population in comfortable transportation with minimal time required a large-scale approach to the implementation of the long-term plan for the development of the subway. Engineering-geological conditions of St. Petersburg are characterized by great complexity in the design and construction of underground structures. Water-saturated unstable sandy-clay soils, often of a belt structure, serve as the host medium for the objects of the underground of small and medium depth. The thickness of Quaternary deposits within the city has a large difference of absolute marks and is characterized by great heterogeneity. Relatively favorable conditions for the construction of underground structures are the layers of Cambrian clays, the full capacity of which varies from 12–20 m to 95–126 m relative to the earth’s surface. The root soils are characterized by sufficient density and uniformity with low water flows and moisture, which led to the deep laying of the vast number of station complexes and distillation tunnels of the St. Petersburg metro.