Settlement prediction of bored piles in stiff clay at a site in the Moscow region

Geotechnical Engineers should devote a considerable amount of time to understanding foundation settlements. When designing in soil deposits that are unfamiliar, pile load testing is essential for investigating likely foundation movements. Simple models to compute pile settlement are also useful for design engineers, especially in soil deposits that are not widely studied or reported. Pile load test data is presented along with relevant site investigation data for a site in the Jurassic clay in Moscow. This clay is of similar age to the Oxford clay found in England. The available site investigation data included Atterberg limit tests and CPT tests. Settlement analysis is carried out from the load testing of 20m long circular bored piles in this stiff over-consolidated clay. A simple MSD-style settlement model was used to backanalyse the results of the load testing conducted at this site. The backanalysis results are compared against the general methods in Russian codes of practice (SNiP/SP). The prediction of pile settlements in Russia generally assumes use of numerical modelling or emprical calculations given in Russian codes of practice, and this paper provides an alternative approach based on a semi-empirical method.