1 INTRODUCTION In this paper, a case-study on the excavation of a metro line in Mexico City is presented, where a real optimization of excavation phases and shotcrete support was achieved. The mathematical functions developed in the first part of this research (García, 2017, García & Sánchez, 2019) were implemented as part of the constitutive behavior of the solid elements and zones represent- ing shotcrete layers at the excavation boundary. Finite element and finite difference models of the tunnel where calibrated to reproduce as accurately as possible the monitored ground. Once the full models where considered as representative of the global response during construction, stresses and forces at the shotcrete lining where used to verify its structural performance. From the review of the geotechnical and constructive aspects during the construction of this particular metro tunnel in Mexico City, it was possible to determine the safety conditions pre- vailing at the excavation before and during the implementation of some changes proposed by the contractor focused on the improvement in the construction procedures and the support sys- tems. With the results of this study the authorities approved such changes, in particular the re- placement of double-welded wire mesh within shotcrete layers, included in the original project, by a mixture of steel fiber reinforced concrete of a type and characteristics such that it complied with the common specifications used in underground works. 1.1 Grid/mesh dependency problem During the modelling of the post-peak behavior of materials, the development and width of shear bands depend strongly on the size of the elements or zones; when strong shear defor- mation fields start to localize, the amount of softening represented by the model will be inevita- bly related to the mesh or grid refinement if any regularization technique is utilized. To better understand this problem, a simple compression test was modeled on a cubic sample of steel fiber reinforced shotcrete. Figure 1 shows the 6 meshes used and the results obtained; it can be observed that before reaching the peak, strength at all graphs is equal, however, even though the 6 models have exactly the same input parameters, immediately after this point the dependence on the mesh is manifested and all the models provide different amounts of soften- ing, being the results from the thinner mesh the most reliable. Advanced constitutive modelling for the approach of real shotcrete performance in tunnels F. A. Sánchez President of the Mexican Association for Tunnelling and Underground Works (AMITOS), Mexico G. G. Saldivar National University of Mexico, Mexico ABSTRACT: The use of advanced constitutive approaches to better represent the behavior of shotcrete during tunnel excavations is a common practice nowadays. Moreover, with some spe- cial mathematical treatments focused on the mitigation of the well-known mesh dependency problem, they can to contribute in creating realistic numerical and geotechnical scenarios that can lead to optimize designs.