Change of ground type by means of dynamic compaction: consequence on the calculation of seismic loadings

Soil improvement works by means of dynamic compaction or vibrocompaction improves mechanical characteristics of granular soils. Experience feedbacks point out the geotechnical conditions which are able to induce ground type change after ground improvement works. In this paper, in case of a two-layer geotechnical model and dynamic compaction technique, the necessary conditions are presented for a ground type change and the consequences on the magnitude of the seismic design loadings are studied for a five-storey building. Therefore, this article does not deal with liquefaction but only with seismic retro-analysis after soil densification.