Eurocode7: geotechnical design (EN 1997 - Part 1) requires that the characteristic values of soil properties is checked using published correlations among the parameters. Virtually no work exists which summarizes all of the correlations published up to the present, a search in the technical literature is time consuming and tedious and the correlations found are often misleading.
To provide a simple and proven method for practice engineers for the evaluation of characteristic values of soil properties using correlations, as required in Eurocode 7 (EN1997): Geotechnical design.
The project will be compiled for Swiss soils (alpine arc soils):
- through a detailed and double-checked bibliographic research
- through the use of statistics on Swiss soils based on over 6000 samples (150'000 values)
This research will also include a study of the best method for the practical presentation of these correlations tests of the correlations found using Eurocode 7.
This research is, in fact, divided into three parts:
- First part is devoted to an analysis of the statistical methods, which may be used with Eurocode 7. This analysis mainly shows that the statistical method advocated in the code is the one most often unrealistic, as it requires a minimum of 10 results for the same tests for a soil layer, which may be considered homogeneous. Such a high number of tests is only carried out in practice for extremely large projects.
- Second part: In 1992, a statistical analysis on Swiss soils was carried out on some 6000 samples, yielding some 150’000 test results. This analysis was based on a former soil classification method and correlations among the various parameters treated were not carried out. In the framework of this research, this analysis was updated using the new Swiss classification method which is very similar to the USCS classification method defined by the ASTM standard D2487 and numerous correlations which were established by using the values contained in the databank. This analysis and the corresponding correlations were carried out for Swiss soils; however, they are certainly valid for the majority of soils found in Alpine regions. This update of the statistical analysis of Swiss soils was already used in the revision of the code SN 670 010 “Soil characteristics”.
- Third part: Since no real work exists which summarizes all of the correlations published at the present time, researching them in the technical literature is long and tedious and the correlations found are often misleading. For this reason, an advanced bibliographic research was carried out and the largest possible number of correlations among main soil characteristics was checked. This research especially concerns laboratory tests and has led to the writing of some 140 records describing one or several correlations. Further part of the project is dedicated to in situ tests; its content is unfortunately more limited than that of the chapter dealing with laboratory tests. Moreover there are summarized all the correlations, both those resulting from the statistical analysis of Swiss soils and those resulting from the bibliographic research.