Evaluation of Drained Stability of Active and Passive Trapdoors for Horizontal and Inclined Soil Bed using Finite Element Limit Analysis

The present study aims to investigate the arching in cohesive-frictional soil under the drained condition by considering the stability number. The use of stability number to evaluate the supporting pressure for a trapdoor in soil with horizontal and inclined beds is examined. The primary method adopted is the equation similar to the conventional bearing capacity equation based on cohesion, surcharge, and unit weight of soil. The finite element limit analysis is used to evaluate the failure envelopes and supporting pressure bracketed between rigorous upper and lower bound solutions, which is the function of the friction angle of soil, embedded depth ratio, and inclination angle of the ground. The stability of the trapdoor is examined corresponding to the transition in the value of supporting pressure from negative to positive correlated with the factor of safety for different embedded depths. The superposition principle for evaluating supporting pressure is also examined. The present study results are compared with those available in the literature. Then, few examples are presented to demonstrate the use of stability number to evaluate the supporting pressure of a trapdoor.