Tunnelling is one of the most difficult fields of ground and rock engineering. However, the many technological advances in modern tunnelling have not been accompanied by a rational understanding of the underlying mechanical problems. Thus, tunnelling remains rather an art than an engineering science and is mainly based on the intuition of few specialists. In more and more cases the lack of rational approach is tried to be overcome by the extensive use of finite element methods in tunnelling. In many cases, however, this powerful tool is not appropriately used and many applications to tunnelling are not convincing. Very often, the assumed loads and material properties are felt to be widely arbitrary. In most cases the input parameters are trimmed to yield intuitively acceptable results.