At the beginning of 2019 the city of Istanbul opened a bigger and brand-new airport in the north-west of the city in order to cover the increasing volume of passengers traveling through Istanbul. In addition to the airport infrastructure, it was necessary to construct a new Metro Line to connect the new airport to the city center, which includes the construction of a double Metro Line of approximately 37.5 km total length with five stations.
For the excavation of this section of the full project, mainly starting from the “Ihsaniye Station” (over 8 km from the total length of the project) the team in charge decided to use 4 different EPB TBM machines from a German manufacturer with an excavation diameter of over 6 m. Two machines are always excavating in parallel. The excavated material is removed using a conveyor belt to a central shaft.
Considering the length of the full project, different types of ground were found during excavation but the most of the advance of the EPB machines was crossing very cohesive soils.
For the sections mainly containing clay, Sika recommended the use of Sika® Foam TBM 510 LS which is a foaming agent for high cohesive soils. For some short sections of the tunnel containing clay and some gravel, Sika specially formulated Sika® Foam TBM 513 AR. The latter is a new foaming agent to produce very stable foam that can be injected during tunneling operations with TBMs in grounds with some rocks that may help protecting the steel structure of the cutting wheel and even extend the lifetime of the cutting tools.
Sika® Foam TBM 510 LS / 513 AR
Ministry of transport, maritime affairs and communications.
Istanbul Metropolitan Municipality