Modeling Pile Setup in Natural Clay Deposit Considering Soil Anisotropy, Structure, and Creep Effects: Case Study

Abstract

In this paper the behaviour of a natural soft clay deposit under installation of a case study pile is numerically investigated. The case study problem includes installation of an instrumented closeended displacement pile in a soft marine clay, known as Bothkennar clay, in Scotland. The site was being used for a number of years as a geotechnical test bed site and the clay has been comprehensively characterised with both in-situ tests and laboratory experiments. The soft soil behaviour, both after pile installation and after subsequent consolidation, is reproduced via an advanced critical state-based constitutive model, namely S-CLAY1S, that accounts for the anisotropy of soil fabric and destructuration effects during plastic straining. Furthermore, a timedependent extension of S-CLAY1S model, namely CREEP-S-CLAY1S is used to study soft soil creep response and the significance of its consideration on examining the overall pile installation effects. The simulation results are compared against field measurements, and for comparison the pile installation is also analysed using the Modified Cam-Clay (MCC) model to highlight the importance of considering inherent features of natural soil behaviour in the simulation. Considerable sensitivity analysis is also performed to evaluate the influence of initial anisotropy and bonding values on simulations results and to check the reliability of the numerical analyses.