Publication

Abstract : Circular tunnels are a common roadway and railway tunnels that are mainly preferred due to the popularity of tunnel boring machines. Tunnels are usually bored in cities where the option of cut and cover method during excavation is not feasible. Hence, it is very critical to analyze the behavior of foundations over a tunnel considering soil uncertainty. A probabilistic study is performed to investigate the effect of uncertainties in soil parameters on the seismic bearing capacity of strip footing over a circular lined tunnel. Soil is assumed to be pure clay. The seismic waves are generated as simple harmonic waves using modified pseudo-dynamic approach. The model is analyzed using lower bound finite element limit analysis. The system failure probability due to soil parameter uncertainty is computed using Monte Carlo Simulation method with the help of random field simulation using Karhunen–Loéve expansion technique. It is observed that the tunnel liner thickness and depth of tunnel has a remarkable effect on the behavior of footing. The inclusion of spatial variability for any case has a failure probability of more than 50%, when the factor of safety is unity. It is also noted that for some cases, even when the factor of safety is 3, the failure probability is not zero.