ABSTRACT
The use of typical rock tunnelling construction methodologies to excavate tunnels in soil is a practice that continues to be found today in some large projects. The erroneous adoption of the NATM philosophy as if it were a sequential excavation (SEM) is the most common case. The excavation by conventional means of tunnels in soils, in which their length does not justify the use of a TBM, is not usually exempt from difficulties. This article presents the case of a tunnel to be excavated in loose fine sand, with an excavation area of about 180 m2, and a few meters of overburden, whose conception in the early stages of design does not fit properly to the existing ground and has subsequently required considerable design changes during construction.
