ABSTRACT
Janbu 1973, Bjerrum & Kjærnsli 1957 were pioneers in developing and applying limit equilibrium (LE) methods in Norway for evaluating stability of natural slopes and manmade fills. In the later years finite element (FE) methods are used, but mainly in academia. The application of FE for practical design is still limited probably because of the need for more soil parameters in a FE simulation and uncertainty in the general use of FE. However, it is the experience of the authors that FE and LE in practice give very similar results if proper input parameters are given and if higher order elements and a sufficiently fine FE mesh are used. In undrained applications, unfortunate shortcomings of simple soil models seem to cause some confusion related to the risk of overestimating the undrained strength in an effective stress analysis. This relates to the fact that normally consolidated clays show significant contractancy upon undrained shearing and significant strength anisotropy. The simple soil models mostly available in commercial FE codes do not offer soil models that can reproduce such behaviour. Still the FE methods can be and should be used for design, but if an effective stress approach is used to an undrained situation, care must be taken to specify input parameters that predict correct undrained strength.
