Publication

Abstract :

Uncertainty is a term that goes hand in hand with any naturally formed material, soil is not an exception. It is common practice to include a large factor of safety while dealing with materials like soil that poses high uncertainty. However, it is high time to understand that a probabilistic approach to this issue gives a better solution to many geomechanics problems, one of which is the tunnel stability problem. In this study, seismic stability of a horseshoe tunnel is analyzed considering the soil parameter uncertainty using random field theory and Monte-Carlo simulation methods. Primary framework of the model is developed with finite element lower bound limit analysis in MATLAB. Seismic acceleration is incorporated into the study with the help of modified pseudo-dynamic approach. Parametric study is carried out to study the effect of the depth of tunnel from the ground surface, height of tunnel, coefficient of variation of undrained shear strength, correlation distance in the vertical direction and the horizontal seismic acceleration coefficient. It is found that the effect of soil uncertainty is more prominent for a non-seismic case. It is also observed that for the highest seismic acceleration, the stability number is independent of the tunnel height.