There is a very significant boom of the tunneling industry in the Czech Republic and generally worldwide in recent years. The main reason is the lack of space on surface in major cities together with requirements for faster traffic connections. Therefore a very significant number of tunnels are either under construction or in the design stage. The recent rapid increase in the capability of computers and user-friendly software has led to a proliferation in the use of numerical analyses in design of underground structures. One important fact is often overlooked. No matter how sophisticated a numerical model is, it is only an approximation of the real situation. The presented paper deals with the optimization of numerical modeling for underground structures. The results of research, which we are working on, should be recommendations for designers of underground constructions using numerical modeling with regard to the application of software and input data. Due to the scope the paper is divided into several parts. The first part is devoted to introduction into current problems. The second part discusses influence of non-linear material model on precision of analyses of tunnels in clays. The last part is devoted to the experience with numerical modeling of underground structures in Prague.