As computer technology evolves, numerical modelling appears to be an increasingly popular tool to obtain solutions
for static or dynamic structural problems in all engineering fields. Tunnelling, on the other hand, is one of the most
empirical engineering disciplines; so applicability and reliability of such numerical solutions may often be challenged.
Yet, in the famous words of G.E.P. Box, “All models are wrong, some are useful” (Box and Draper 1987). Numerical
methods have become standard practice and are indeed a very useful tool for the analysis of complex tunnel
structures, as many recent design and consulting projects have shown. In the authors’ perspective a well prepared
simulation of an underground structure can give a good and communicable description of the structural behaviour,
indicates risks, and highlight issues deserving additional attention during design or construction, and provides
substantial aid to the project development. This paper attempts to offer practical information and disclose
significant aspects of numerical simulations in tunnelling based on the authors’ experiences in research and
applications on a wide range of projects in- and outside the UK. These have also been addressed during the BTS-
YM meeting of 04/10/2012 under the title “Numerical Modelling” (http://ice.adobeconnect.com/p3dme3hyxud/). It
should be noted that the main background of the authors reflects SCL tunneling, yet the general concepts discussed
herein apply to other types of underground structures as well.
In the first part of the paper, the purpose of using numerical solutions in tunnelling is explained, together with a
discussion on the advantages and disadvantages in engineering terms. Furthermore, some practical rules and hints
on the implementation and verification of numerical models are outlined. The paper concludes with advice on the
use of numerical models in design projects and some rationalisation of a modelling campaign in terms of cost (or
effort) efficiency.