The trapdoor problem is a useful model to understand the stress distribution around geo-structures. This paper focuses on evaluating the conditions of maximum arching (minimum loads on trapdoors) developing during the lowering of plane-strain active trapdoors in cohesionless granular materials. A parametric study using finite element analysis has been performed to investigate various factors affecting the maximum arching conditions in active trapdoors, with a particular focus on the effect of soil dilatancy. The paper also presents rigorous upper bound limit analysis solutions. Previously published solutions dealing with soil non-associativity have been discussed and compared with the finite element results. The finite element analysis shows that using a Mohr Column model with the associative flow rule and reduced strength parameters, overestimates the load reduction on trapdoors compared with a non-associative model with full soil strength parameters.