Planar assemblies of interlocked cubic blocs have been tested in indentation. Experiments are performed on blocs made of plaster. Influence of key parameters such as the surface roughness, the compression stress and the number of blocs are investigated. A numerical modeling is then proposed based on discrete element method. Each bloc is represented by its centre coordinates. Constitutive equations obtained by finite element simulations are introduced to model the contact between the blocs. The numerical tool is then applied to the case of indentation loading. It is found that the model reproduces all the experimental tendencies.