Influence of EC7 design approaches on the design of deep excavations with FEM

In the current version of EC7, three different design approaches are defined, which differ in their application of partial factors on actions, soil strength and resistance. When analysing deep excavations two problems arise, first the fact that soil can act as both load and resistance, and second that, when employing numerical methods, earth pressures are not an input into the analysis, which can be factored accordingly, but are a result of the analysis. By comparing the results obtained from simple examples it will be shown that different design approaches can be readily employed in combination with numerical methods although some differences in the results may be expected. From the studies performed, another preliminary conclusion can be drawn, namely that the influence of the design approach seems to be less significant when employing advanced elasto-plastic constitutive models incorporating strain hardening behaviour as compared to elastic-perfectly plastic failure criteria. However, further studies are required to confirm these findings.