Boundary Element Methods for the Simulation of Underground Construction

For the simulation of underground excavation (tunnelling or cavern excavation) the Boundary Element Method offers advantages. For infinite or semi-infinite domains the radiation condition is explicitly fulfilled and the effort in discretization (surface instead of volume discretization) and solving the modelling system is reduced by an order of magnitude. One of the reasons why the method is applied rarely in practice is that essential aspects, such as modelling the sequential excavation, the efficient treatment of nonlinear material behaviour, inhomogeneous ground conditions and support construction were missing. In addition the method requires more computational efforts, run times for large 3D problems can become unacceptably long. The paper will present the research work carried out at the Institute for Structural Analysis at Graz University of Technology (with European and Austrian sponsorship). The research includes the implementation of efficient methods dealing with the above mentioned requirements for a practical application of the method to underground excavation problems.

It will be shown on a 3D example in tunnelling how the method can now efficiently deal with the sequential excavation / construction. Fast solution techniques were implemented to ensure that the results are obtained in a reasonable time for large 3D problems.