Scientific paper ID 1960 : 2020/3

According to the latest data, 1.3 million people live in our capital. For more convenient and fast movement of the city”s residents, the building of one of the most modern subways in Europe has begun. The construction of tunnels is responsible and challenging engineering task. The specialists have to overcome various obstacles associated with geological characteristics of the terrain,water level, under rivers, under existing buildings and structures, under roads and comunication on the surface, with the currently available equipment and machines. Аnd all this can be done within the prescribed terms, and of course, with a guarantee of future safe and reliable work. Article considers methods used for build subways and those that were applied during the construction of the Sofia metro. Four types of construction methods are mainly applied: classical open pit – method, Milanese method, shield method and new Austrian Tunneling Method. The main features of these difrent methods are shown. The used geothechnical structures are presented. The technological order for construction of tunnels in different methods is shown. The advantages and disadvantages of used methods depending on existing conditions are highlighted. Analise of diferent methods and teir implementation according to the geotechnical conditions are given.