Laboratory tests on Dutch limestone (Mergel)

In this note, results of triaxial laboratory tests on very weak sedimentary limestone
from the construction of the “Geusselt A2” tunnel in Maastricht in the Netherlands are presented. The main purpose of the triaxial tests was to evaluate the strength of this rock. Particularly interesting was that the strength parameters obtained in the laboratory, were much lower than what was expected after preliminary visual inspections. The two most popular models in soil and rock mechanics, the Mohr-Coulomb and Hoek-Brown failure criteria, were used to estimate the strength parameters and both did not give satisfying results. Still the Mohr-Coulomb model is the best model to use.