The influence of dynamic loads on postglacial lacustrine fine-grained deposits

In earthquake engineering it is well known that different types of soil, especially sand, have the tendency to liquefy due to dynamic loading. In this research, the dynamic loads are caused by construction methods like jet grouting, vibro compaction or vibro replacement and vibrated sheet pile walls and the soil types investigated are postglacial lacustrine fine-grained deposits, in general silt with different amounts of clay and/or fine sand. The most common liquefaction criteria the “Chinese criteria”, Wang et al. (1979) does not fit for this type of soil. It shows in some cases similar liquefying or softening behaviour. Results using the liquefaction susceptibility criteria, Boulanger and Idriss (2006), are presented in this paper. Furthermore a case study to determine dynamic loads like acceleration and changes of pore water pressure during jet grouting is presented.