Cross-correlated Random Field Models of Passive Trapdoor Stability in Clays with Shear Strength Linearly Increasing with Depth

The failure mechanisms of a trapdoor can be elucidated through the interplay of the soil unit weight causing a downward and a constraint on the soil shear strength. In this study, random adaptive finite element limit analysis was employed to explore the impact of spatial variability in a correlated random field on limit load and probability of design failure for a passive trapdoor embedded in nonhomogeneous clay. The investigation delved into the influence of the cross-correlated coefficient between the unit weight and the undrained shear strength of clay, considering various dimensionless strength gradients and trapdoor cover ratios. The findings revealed that an increase in the cross-correlation coefficient with higher probabilities of design failure. Failure tendencies were observed to escalate with rising dimensionless strength gradients and trapdoor cover ratios. Design charts for different trapdoors were also provided in the paper, aiding selection of the required safety factor to meet the desired probability of design failure. This work proves valuable for the practical applications, as it considers both the effect of spatial variability in correlated random fields and nonhomogeneous soil layer.