Conventional manual-based design is being shifted to performance-based design in the geotechnical engineering practices. During these changes, it is not clear how to treat the conventional limit equilibrium methods for the bearing capacity, earth pressures and slope stability problems. Limit equilibrium methods are similar to the limit analysis. However, theoretical consistencies are lost in the limit equilibrium methods, because bold assumptions and empirical relations are included. Originally, rigid-plastic analysis can be very useful for the practical design because of its theoretical simplicity, fewer material parameters and its stability in the calculations. In this article, mechanics and mathematics of limit analysis are reviewed in comparison with other methods. Recent developments of numerical rigid-plastic methods are also reported. The author thinks these kinds of knowledge should be utilised for the reconstruction of plastic design procedures in geotechnical engineering practices.