TABLE OF CONTENTS The working group "Excavations" (EAB) of the German Geotechnical Society (DGGT) have extended the known standard recommendation for excavations to include a new recommendation for excavations in soft soils (EAB 2006). Some information and specification from this new recommendations have been already presented in section 4.3 and 4.5. In the following are some more extracts from the recommendation regarding strength parameters, earth and water pressure calculations, determination of embedment depth and section forces, stability requirements as well as drainage in excavations.
Based on the discussion on the drained and undrained analyses (Kempfert and Gebreselassie 2002) (see also section 4.7) and the analytical parameter study on undrained analysis of excavations in soft soils by Hettler et al. 2002, EAB recommends to use mainly the drained analysis as governing method of the calculation of excavation in soft soils, but leaves room for the geotechnical expert to decide based on the situation at the site. To perform the drained analysis, one requires the effective shear parameters. These can only be determined in triaxial or direct shear tests in laboratory. However, the soft soil is very sensible to such kind of test. The disturbance of the structure of the soil specimen during sampling, the rubber membrane used in triaxial test, and the friction resistance in shear box, etc. might lead to failure in estimating the shear parameters, and hence the laboratory tests...
