Modern metro lines can be either underground and aboveground, passing over the carriageways of the city or on their own route on special veils-withdi. Construction can be carried out in an open and closed way, depending on the conditions of the site, soil state and safety requirements and the preservation of the existing architecture
Construction of a new metro: design
Like any construction, laying the new metro branch begins with large -scale design. A large block of engineering surveys is carried out, on the basis of which the project will be developed. They include an extensive block of geological and geodetic and environmental research. If necessary, more complex studies are carried out. It is necessary to find out how stable the soil on the path of the future branch is, what obstacles arise and how safe it will be to build one or another method.
Any metro lines are designed and built on the basis of a complex of SNiPs including, instructions on a complex of engineering surveys, depth of the occurrence and structure, as well as used materials and elements.
In addition, the project indicates the route of the rising branch, indicating where there will be both sub- and the aboveground part of the route.
Construction of a new metro: Work methods
As already mentioned, the metro is laid both closed and open. The first is preferable in urban conditions, t. To. does not violate the already established view of the city and does not violate the traffic. This is a method for both deep and petty. Under him, to unload the waste soil and supply of the necessary materials, special mines will be equipped, along the path of the head passing detachment.
Depending on the geological conditions, the methods of shield penetration and methods of continuous and mountain slaughter are used.
The first most advanced method to date is the use of a large combine of the round section, which produces the sleeve to a full diameter with complete or partial processing of its walls. In the second case, the production is also carried out for the full diameter of the sleeve, but temporary fasteners are installed for the subsequent decoration of its walls. In the third case, development is carried out gradually for both operations.
The open method involves volumetric earthwork and extensive engineering preparations related to the transfer of communications and transport highways. With it, the depth of the branch does not exceed more than 10-15 m.
Work in this way is carried out either with a foundation or trench method. In the first case, the pit breaks out to the sole of the future tunnel. The tunnel is completely built in the pit, and then falls asleep. In the second method of work, they go in parts, the walls of the trenches are temporarily supported by fasteners.
At the present stage, they prefer to combine the methods of open and closed construction, which allows us to maximize the advantages of each of them.