Open cast coal mining in Northern Bohemia produces overburden waste of overconsolidated clay lumps that are placed in spoil heaps or used as backfill in exploited mines. This forms landfills with a double porosity structure consisting of voids between lumps (inter-granular) and voids within lumps (intra-granular). The total porosity can be up to 70 %, making the soil highly compressible even after self-weight consolidation. Soil behaviour is characterised by large absolute and differential settlements. Dynamic compaction is one of the ground improvement methods used before construction on these clay landfills. Model tests on scaled double porosity clay landfills were carried out in the ETH Zurich drum centrifuge. A period of self-weight consolidationwas followed by in-flight dynamic compaction. To assess and compare the strength of the clay fill, in-flight displacement-controlled rigid foundation tests were carried out on the centrifuge models. The total load on the foundation, and pressure distribution under it, were measured. © 2009 IOS Press.