Three-dimensional finite element calculations in soil and mining engineering

The finite element (FE) calculation is an efficient tool within the set of instruments used in tunnel design. Nowadays practically no major project is done without such calculations. This is due to the fact that FE calculations allow even complex rock-mechanical conditions to be modelled realistically and with an acceptable expenditure of manmonths. Using realistic material laws and accordingly exact models - Among them also 3- dimensional ones - the calculations allow reliable prognoses. These serve as a basis for making technical and economic decisions. The present paper is concerned with two 3-dimensional FE analyses for projects in which the authors themselves were involved. The main concern of this paper is to describe the application and the results of these FE-calculations and their impact on engineering practice. Both tunnel drives were executed in accordance with the principles of the New Austrian Tunnelling Method. For details concerning the two projects described the reader is referred to the list of literature cited.