The aim of the present study is to assess the impact of rotational anisotropy on the undrained bearing capacity of a surface strip footing over an unlined circular tunnel on spatially variable clayey soil. The finite-difference method (FDM) is utilised to perform both deterministic and stochastic analyses. The Monte Carlo simulation approach is used to estimate the mean stochastic bearing capacity factor (mu Npro) and probability of failure (pf) of the entire system. The responses are evaluated for different geometric and spatially variable parameters and the strata rotation angle (beta). The failure patterns and the required factor of safety (FSr) corresponding to a specific probability of failure (e.g. pft = 0.01%) are determined for various parameters. The results obtained for the rotational anisotropy (beta$\ne \;$not equal 0) are observed to be significantly different from those for horizontal anisotropic structure (beta = 0), and considering only the horizontal anisotropic structure may lead to the overestimation or underestimation of the response of the structure.

The present study explores the effect of rotational anisotropy on the bearing capacity responses of the square and rectangular footings using the random finite difference method (RFDM) and Monte Carlo simulation (MCS) technique. Three different aspect ratios (i.e., L/B = 1, 2, and 3) are considered in this study. The lognormal distribution is chosen for the spatial distribution of the tangent of the friction angle. The probabilistic bearing capacity response (mu N gamma) and the failure probability (pf) of the footings are obtained for different angles of rotation of the soil strata (beta) considering different orientations of the footings. The probabilistic results are presented in the form of PDF and CDF for different beta and L/B ratios of the footing. The desired safety factors (FSr) corresponding to a specific target failure probability (say pft = 0.01%) are also evaluated for different beta. It is found that the orientation of the rectangular footings with respect to the strike direction of the soil strata has significant effects on the mu N gamma and pf of the footings.