Within the framework of the research project, a calculation model was developed for a combined radial symmetrical compression and consolidation around the ash columns which allows a reliable assessment of this improvement method. The improvement effect of those ash columns can also be verified with the help of large-scale oedometer tests in laboratory. Therefore, it is possible to determine the calculation parameter necessary for a measurement. (orig.)Available from TIB Hannover: F00B693+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman