Geotechnical Engineering Journal of the SEAGS & AGSSEA ISSN 0046-5828
Vol. 51 No. 4 December 2020
Reliability of ULSD Theory in Geotechnics
P. Koudelka
ABSTRACT: The article discusses the theory of ultimate limit state design (ULSD) and its consequences. An influence of definitions both characteristic and design values of soil parameters of EN 1997-1 (Code) is analyzed. The article has two basic theoretical aims: a) To demonstrate the incorrectness of ULSD in geotechnics and due to it in-effectivity and risk. b) To present a concept of a more plausible and correct design theory which is simpler and in compliance with mathematical principles. A case of slope design is chosen from basic geotechnical problems because slope masses are most sensitive. Slope designs based on the design approaches of the Code are compared with a direct design value definition-based approach. Slope analysis exploits the results of a statistical analysis of an extensive database of soil material properties. The analysis is based on data sets of sandy and fine-grained soils and demonstrates the risk of homogeneity for ULS designs. Another simple geotechnical design concept suitable also for advanced numerical methods is suggested and a procedure example is presented.
KEYWORDS: Design theory reliability, Design value definition, Soil property database, European standard EN 1997-1, Slope design.
