In order to study scaling phenomena in granular materials, simple extensions of a model originally proposed by Jullien, Meakin and Pavlovitch (Phys. Rev. Lett. 69, 640 (1992)) are developed. It is shown that the model reproduces phenomena like the heap formation due to friction at the container walls during vertical shaking, as well as size segregation in a rotating drum. The geometrical mechanisms underlying these phenomena are discussed, as well as preliminary results about the critical behavior.