ABSTRACT
The Saint Martin La Porte « SMP4 construction site » is the last exploratory gallery of the 57,5 km long TELT project. In 2017 the excavation works of Part 3b commenced using the conventional method. Part 3b is a 1,5 km long section of the south tube that crossed the Houiller Front, a Carboniferous formation characterised by squeezing ground behaviour with high overburden. This Paper describes the successful crossing of the largest fault zone encountered at Ch 10+600 during the excavation of the exploratory tunnel. This fault has an extension of about 80 m with high squeezing rocks composed mainly of fault gouge, coal and tectonized shale. This geological accident demonstrated the successful application of the most recent innovations in yield-control support systems applied to conventional tunnelling as a result of more than 15 years of research work on “squeezing rock” at the Saint Martin La Porte site.
