Some recent developments in the finite element analysis of shallow tunnels

A constitutive model for soils including strain hardening plasticity and the so-called small strain behaviour for soils is presented. Some results from finite element simulations of shallow tunnels, where comparison is made to elastic perfectly plastic models, show that more realistic surface settlement troughs are obtained with the proposed model. In the second part of the paper a similar model is formulated within the multilaminate framework and is enhanced to include strain softening behaviour. The model is capable of simulating the development of shear bands and thus potential failure mechanisms can be identified.