On 17.10.2017 the New Albula Tunnel of the Rhaetian Railway (RhB), the breakthrough into the reverse drive of the cavern was achieved. With this, the excavation from Preda (main lot) met the reverse drive which has previously been excavated from a cavern. The reverse drive was commissioned separately for the excavation of the Raibler-Cornieule (most delicate zone of the massif at the Albula tunnel). The new Albula Tunnel II is being constructed parallel to the existing Albula Tunnel with an axial distance of 30 m. When constructing the first Albula Tunnel I, the aquiferous zone of the so-called Raibler-Formation (cell dolomite rock) already revealed to be a geologically difficult zone. In 2013, starting from a specially excavated cavern connected to the existing tunnel, exploration drillings have been done in the whole Raibler-Formation zone in order to develop a more accurate geological model. Following the drillings results, the Raibler-Formation can be subdivided in three different geological sectors. The sector denominated III is a fault zone of silty fine sand (swimming Raibler-Formation) with a water pressure of approximately 5 bar. For safety reason the sector III will be excavated with the freezing method.

Lombardi, in an engineering consortium, is responsible for the construction supervision of the reverse drive from the cavern, including the special construction measures such as freezing method and solidification injections. Click here and ch/101 for tunnelbuilder archive. Visit https://www.rhb.ch/ and https://www.lombardi.ch. 46/17.

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Ch/101=> http://tunnelbuilder.com/Archive/Projects.aspx?&projectcode=ch%2f101

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https://www.rhb.ch/fileadmin/user_upload/redaktion/Ueber_die_RhB/Medien/Dokumente/Medienmitteilungen/Medienmitteilungen_2017/2017.10.17_Albulatunnel_Durchstich_in_die_Kaverne.pdf