By using Schneebeli's rod material for simulating an ideal granular mass in plane strain, a series of model trap-door tests has been performed with the main objective of checking the validity of the classic bin theory when applied to this class of problems. In the tests, the pressure on the trap-door was measured, and the rod displacement trajectories were photographically recorded. A comparison of measured and calculated pressures acting on the trap-door both during its downward and upward movement, shows that the pressures can reasonably well be predicted by assuming the existence of two limiting vertical failure planes as in the classical bin theory, provided proper considerations are made concerning the ratio and the value of normal stresses acting along these planes.