Today, the UmbrellaArch (umbrella arch system) method has been developed under the name of arched methods of tunneling in poor ground conditions.
The purpose of this method is to create a fortification shell around the tunnel excavation mirror without any excavation in the tunnel face, and then to make progress by excavating under this safe shell.
In these excavations, it should be ensured that the normal section of the tunnel is expanded by 50 cm within 3 meters of progress. Umbrella pipes should be driven concentrically at 30 cm intervals around the tunnel mirror in the area where the application is made, and their inclination should be 5-8 degrees upside down.
Standard dimensions for Umbrella Arch and equipment (Pipe, Ring Bit and Pilot Bit) are given in the table below.