Tuzun and Nedderman (1983) observed the
presence of an wedge-shaped insert affects the wall stress distribution in different ways
during filling and discharging. Scholz (1988) measured an increase in the wall normal
stress at the level of the insert during filling and during discharging if an wedge-shaped
insert was positioned in the vertical section of the silo; no increase was observed
otherwise. Measurements carried out under symmetric conditions of silos (Kroll, 1975;
Kahl, 1976; Scholz, 1988) showed that the vertical load exerted on a wedge-shape insert
in silos are significantly higher than the loads which result from Janssen's formula of the
vertical stress in the vertical section of a silo.