Numerical Methods: FEA
With the aid of nowadays computers, numerical methods have become a very useful tool for designing underground structures. Finite element methods, one of the most used methods, are based on the principle of discretization of a body into a number of finite elements. The behaviour of these elements can be controlled by imposing certain laws of mechanics in a predefined manner under the action of external influences. Finite elements methods can be used to model the behaviour of tunnel structures for a variety of assumed ground conditions and geometries; these include linear or non-linear elastic responses and non-linear material behaviour (plasticity). These methods normally model the ground as a continuum medium, but some of them also allow to model the ground as a discontinuum medium that represents much better the behavior of rock masses that are heavily fractured.