Ameir Altaee

Pile Dynamics in Geotechnical Practice—Six Case Histories

Six cases are presented showing the benefit of dynamic testing and analysis of driven piles, comprising (1) a comparison between two types of piles and a correlation between CAPWAP determined capacity and load-movement response to that determined in a static loading test, (2) the benefit of time-dependent increase of pile capacity, (3) a study how a soil plug can be shown to replace a pile shoe, (4 & 5) the effect on pile capacity from removing soil inside the pile, (6) set-up and effect of excavation. Together the cases show that the dynamic testing can be used to investigate problems in design and construction of piles much beyond a simple capacity determination.

Finite element applications of a bounding surface plasticity model

Bardets bounding surface plasticity model was used to analyze two different boundary value problems: the load-displacement responce of a model-scale footing resting on the sur-face of a sandy silt, and the behaviour of the Leighton Buzzard Sand in the Cambridge Simple Shear Device. Comparisons between experimental observations and the results of the finite element analyses proved the ability of the constitutive model to simulate accurately the soil behaviour in boundary value problems.

A mathematical model for soils

Two mathematical models developed previously by Lade for the stress, strain, and strength behaviour of soils are combined in this paper. The first model, which has only an open ended conical yield surface, is modified by adding a cap yield surface. With this addition, the predictions for soil behavior in laboratory experiments are improved along the stress paths remaining within the current conical yield surface. The capabilities of the present version of the model are evaluated by comparing the calculated and measured response of soil in proportional loading, isotropic compression, and reloading in a triaxial stress path. The differences between the two versions of the work hardening model with and without a cap are illustrated.