A. Soroush, R. Jannatiaghdam,
Volume 10, Issue 2 (6-2012)
Abstract
This paper studies thoroughly and deeply the results of about one hundred triaxial compression tests on thirty types of rockfill
materials. The materials are categorized in accordance with their particles shape (angular / rounded) and gradation
characteristics. The main tool of the study is the Hyperbolic Model developed by Duncan and Chang. The focus of the study is
on the variations of deformation modulus of the materials (Ei and Et) with confining stress (&sigma3). Features of the mechanical
behavior of the rockfill materials, as compared with the general behavior of soils, are highlighted through the exponent
parameter (n) of the Hyperbolic Model. It is shown that high confining stresses may have adverse effects on the deformation
modulus of the rockfill materials and make them softer. The particle breakage phenomenon which happens during compression
and shearing is found as the main factor responsible for the above effects and, in general, responsible for controlling the
behavior of the materials. For the rockfill materials of this study, two correlations for estimating the initial elasticity modulus (Ei)
and the internal friction angle (&phi) in terms of particles shape, confining pressure (&sigma3), and coefficient of uniformity (Cu) are
suggested.
Q. Q. Zhang, Sh. C. Li, F. Y. Liang, M. Yang, Q. Zhang,
Volume 12, Issue 2 (4-2014)
Abstract
A simplified approach for nonlinear analysis of the load-displacement response of a single pile and a pile group is
presented using the load-transfer approach. A hyperbolic model is used to capture the relationship between unit skin friction
and pile-soil relative displacement developed at the pile-soil interface and the load-displacement relationship developed at the
pile end. As to the nonlinear analysis of the single pile response, a highly effective iterative computer program is developed
using the proposed hyperbolic model. Furthermore, determinations of the parameters related to the hyperbolic model of an
individual pile in a pile group are obtained considering interactions between piles. Based on the determinations of the
parameters presented in the hyperbolic model of an individual pile in a pile group and the proposed iterative computer
program developed for the analysis of the single pile response, the conventional load-transfer approach can then be extended
to the analysis of the load-settlement response of an arbitrary pile in a pile group. Comparisons of the load-settlement
response demonstrate that the proposed method is generally in good agreement with the field-observed behavior and the
calculated results derived from other approaches.