The ultimate bearing capacity and the failure mechanism of cohesive-frictional soils with inclusion of shallow tunnels have been theoretically and numerically investigated assuming plain strain conditions. Despite the importance of the stability of foundations above such tunnels/openings, research on this subject has been very scarce. At present, no generally accepted design or analysis method is available to evaluate the ultimate bearing capacity of cohesive-frictional soils with shallow tunnel inclusions. In this study a continuous loading is applied to the ground surface, and the smooth and rough interface conditions between the loading and soils are modelled. For a series of tunnel geometries, shapes and material properties, rigorous upper and lower bound solutions for the ultimate bearing capacity of considered soil mass are obtained by applying recently developed numerical limit analysis techniques , . For practical suitability the results are presented in the form of dimensionless stability charts, with the actual bearing capacities being closely bracketed from above and below. As an additional check and also a handy practical means, the upper bound rigid block mechanisms for circular tunnels have been developed and the obtained values of collapse loads were compared with the results of numerical limit analysis.
2nd International Conference on Computational Methods in Tunnelling, 2009 (EURO:TUN 2009). Proceedings of the 2nd International Conference on Computational Methods in Tunnelling 2009, Volume 2 (Bochum, Germany 9-11 September, 2009) p. 817-824