2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Dr. Biao Li, Concordia University
The stress–strain behavior of soft clay is clearly dependent on time and rate and such time dependency behavior should be considered in geotechnical engineering project such as bearing capacity evaluation for a foundation. Most previous studies focus on elastic-viscoplastic behavior of clay soil under an undrained stress path condition. The developed constitutive models cannot simulate the strong time dependent stress-strain relation of soft clay under drained stress path condition. Most recent study showed that the stress-strain relation of soft clay is strongly dependent on the applied strain rate even if the fully drainage condition has been satisfied. The strong strain-rate-dependent soil behavior is due to the shear creep, which was not properly considered in most previous researches. In the long-term bearing capacity analysis for a shallow foundation, the neglect of the time dependent stress-strain relation of soft clay may result in inaccurate result.
In this study, finite element modeling on long-term bearing capacity of a shallow foundation on soft clay is performed. The strain-rate-dependent soil behavior is modeled using the Drucker-Prager/Cap model with the consideration of soil creep behavior. Both consolidation creep and shear creep mechanisms are considered in the modeling.