Physics-based and data-driven modeling for basal stability evaluation of braced excavations in natural clays

Abstract

The design of fully braced excavation of underground works, whether in rural or urban areas, is important to ensure that the design of fully braced support is safe, particularly in determining the depth of excavation and inserting the length into the clay of the wall, as well as a proportional excavation width. This study investigates the undrained basal stability of fully braced excavation in anisotropic clays with linearly increasing shear strength with depth employing upper and lower bound finite element limit analysis under symmetry plane conditions based on the AUS failure criterion. The dimensionless variables were used to examine the stability number (N) and the failure mechanisms selected for this problem's practical analysis. There is an anisotropic strength ratio (re), depth-wide ratio (B/H), embedded wall depth ratio (D/H), and strength gradient factor (ρH/Suc0). This study proposes design charts and failure mechanisms for fully braced excavations based on finite element limit analysis. Moreover, the artificial neural network model (ANN) was used to establish the relationship between the investigated and output variables and to conduct sensitivity analysis. Therefore, the developed ANN formula is a pragmatic approach for geotechnical engineers to calculate the basal stability of the excavations.

Keywords

• Basal stability
• Plane strain excavation
• Anisotropy
• ANN
• FELA