Draft:Tubing

Prefabricated tubing – a type of cylindrical casing of a tunnel or duct made of metal or reinforced concrete. The connected tubes form a ring, which forms the canal wall. They are most frequently used for the construction of ventilation shafts, mine shafts and metro tunnels (the metro in Warsaw was partly built using this technology).

The first road tunnel under the river in Poland, built using the TBM method, is the tunnel named after Abp. Tadeusz Gocłowski under the “Martwa Wisła” river in Gdańsk. The outer diameter of the tubes is 12,2 m. For its construction, 1076 prefabricated rings with a total weight of approximately 118 thousand tons were used.

Durability of tubes
The tubes should be characterized by adequate strength for two types of loads. They ought to be resistant to the pressure of the rock mass. In addition, they must be designed in such a way that they can transfer without damaging the significant forces that result from the pressure of the left dial during its forward movement during tunneling. The siphon pistons then find support in the previously installed casing ring. The loads of the tubes from significant, sometimes amounting to several hundred tons, forces focused on the siphons are sometimes so large that they determine the dimensions of the tubes. The dimensions of the tubes depend on the load, including the forces focused on the siphons. This applies especially to their longitudinal ribs (programs for building permits). Additionally, when designing a tube housing, it is necessary to take into account the loads that may occur at the stage of tube production and during their transportation.