Numerical analysis of discontinuous berm-supported shallow excavations for building construction

The use of discontinuous berms remains a common strategy in medium-rise urban excavations when a uniform slope is not safe enough and certain conditions are met. However, despite its frequent use, there is no broad and contrasted reference that allows its design and verification in a similar way to how it is done in the usual homogeneous slopes, either by abacus such as those of Taylor or Hoek and Bray or the two-dimensional numerical calculation with bishop’s method, finite elements, or finite differences, among others. The difficulty associated with the calculation of slope stability with discontinuous berms lies in the fact that it is basically a three-dimensional problem, not admitting any of the simplifications that allow it to be reduced to a two-dimensional case and use one of the methods mentioned above. The present research is oriented to model an excavation with discontinuous berms, considering its three-dimensional configuration and including as main variables the height of the excavation, the width between berms, and the properties of the terrain, represented with a Mohr-Coulomb failure criterion. From a large number of calculations, the necessary regressions will be obtained to allow a pre-design and verification of the main cases that arise in practice. The article presents the results obtained and details the advantages and disadvantages of the associated methodology.