Modelling of viscous effects in natural clays
A new approach to allow the modelling of the viscous behaviour of natural clay soils, including creep, stress relaxation and the effects of applied strain rate on soil stiffness, has been developed based on the BRICK constitutive model (published by Simpson in 1992). The new model, "strain rate-dependent" (SRD) BRICK, was used in a series of simulations to demonstrate its capabilities in predicting realistic behaviour during one-dimensional compression and undrained triaxial tests in which applied strain rates were varied. Triaxial stress path tests conducted by Gasparre et al. in 2007 to assess the influence of creep, resulting from recent stress history, on soil stiffness were also simulated. The observed trends concerning the stiffness at small strains were successfully modelled.
Lessons learnt from a deep excavation for future application of the observational method
Abstract This paper draws lessons learnt from a comprehensive case study in overconsolidated clay. Apart from the introduction of the case study, including field measurements, the paper draws on the observations and a three-dimensional (3D) numerical analysis to discuss the implications of observations in the application of the observational method (OM) in the context of the requirements of EUROCODE 7 (EC7). In particular, we focus on corner effects and time-dependent movements and provide initial guidance on how these could be considered. Additionally, we present the validation of a new set of parameters to check that it provides a satisfactory compliance with EC7 as a set of design parameters. All these findings and recommendations are particularly important for those who want to use the OM in similar future projects.
ANISOTROPIC ELASTIC PARAMETERS FOR SOIL
Synopsis The concept of soil as an anisotropic elastic material is considered and the theoretical bounding values of the relevant elastic parameters are described. The bounding values of the parameters are repre-sented in three-dimensional space. Within the space any given material is represented by a point and points in certain regions represent particular types of material. The requirements for infinite bulk modulus, for uncoupled volumetric and distortional phenomena and for dilatant soil are repre-sented within the bounds of possible materials. On considere le concept du sol en tant que materiau eĺastique anisotrope et on decrit les valeurs limites theoriques des parametres d'elasticite s'y rapportant. Les valeurs limites des parametres sont repre-sentEes dans un espace a trois dimensions. A l'interieur de l'espace, tout materiau donne est represente par un point et des points dans certaines zones representent des types particuliers de materiaux. Les conditions requises pour un module de masse infinie...