2851
Behavior of Vertical Piles Embedded in Sand under Inclined Loads near
Ground Slope
Comportement de pieux verticaux ancrés dans une couche de sable à proximité d'une pente
Sakr M.A., Nasr A.M.
Faculty of Engineering, Tanta University, Egypt
ABSTRACT: Pile foundations are used to support structures exposed to different types of loads. Among these loads are
inclined loads which give axial and lateral loads. The main objective of the present paper is to investigate experimentally the
effects of inclined load on axial pile displacement and lateral pile response for piles embedded in the level ground and near
ground slope. The factors considered for this purpose are slenderness ratio for pile (L/D), relative density of sand (D
r
),
distance of the pile head from the slope crest (B/D), and the inclination of the applied load with the vertical. The behavior of
the piles in the level ground was compared with the behavior of piles located near ground slope. Different results were
obtained for combined axial and horizontal loading. From test results, the inclination of the applied load has a significant
effect on the ultimate axial and lateral loads for pile, lateral pile deflection, and the bending moment along the pile shaft
especially near ground slope. The coefficient of horizontal modulus of sub-grade reaction decreased when the inclination of
the applied load increased.
ABSTRACT: Les fondations sur pieux sont envisages pour des structures soumises à différents types de chargement parmi
lesquels on distingue ceux à composante latéral. Ce papier présente une étude expérimentale qui analyse l’influence de
l’inclinaison d’un chargement sur le déplacement vertical et la réponse latérale d’un pieu ancré dans un sol à proximité
d’une pente. Les paramètres d’influence sont l’élancement du pieu (L/D), la densité relative (D
r
), la distance horizontale
séparant le pieu de la pente (B/D) et l’inclinaison de la charge par rapport à la verticale. Le comportement des pieux dans un
massif horizontal est comparé à celui de pieux à proximité de la pente à partir de résultats obtenus pour des chargements à
composante verticale et horizontale. Il a été conclu que l’inclinaison du chargement à une influence considérable sur la
capacité portante ultime sous charges verticale et latérale, le déplacement horizontal et le moment de flexion le long du fût
du pieu, en particulier à proximité de la pente. Il a été également vérifié que l’augmentation de l’inclinaison du chargement
conduit à une diminution du module de réaction horizontale.
KEYWORDS: Vertical piles, inclined load, sand slope, axial and lateral displacement.
MOTS CLÉS:
Pieu vertical, charge incline, pente en sol sableux, déplacemenst vertical et horizontal
1 INTRODUCTION
Pile foundation for several types of structures is often
subjected to simultaneous axial and lateral loading.
According to current practice, piles are independently
analyzed first for the axial load to determine their bearing
capacity and settlement and then for the lateral load to
determine the stresses and deflections. Several results of
investigations on the behavior of piles subjected to
inclined loading have been reported in the literature, e.g.
by Chari and Meyerhof (1983), Sastry and Meyerhof
(1990) and Abdel-Rahman and Achmus (2006).
Poulos and Davis (1980) suggested that the
failure of a vertical pile exposed to an inclined load can
be treated as the ultimate load capacity is a function of
both the lateral resistance and the vertical load capacity
of the pile. When the applied load deviates slightly from
the axial direction, the failure will essentially occur due
to the axial slip while lateral failure will occur when the
inclination is large; that is the load becomes nearly
perpendicular to the pile axis.
Six model tests were performed on aluminum
closed-ended piles by Christos and Michael (1993) to
investigate experimentally any possible effects of lateral
loading on axial pile displacements and stresses as well
as the influence of axial loads on the lateral pile
response. The main findings were the following: the
effect of axial loading on the lateral pile response was
rather limited. The interaction between axial and lateral
pile responses can be studied with a nonlinear finite-
element analysis, while the conventional elastic half
space and subgrade reaction methods of pile analysis
cannot consider this interaction.
According to Vankamanidi and Geoffrey (1999),
the lateral soil pressure, bending moments, pile
displacements at the ground surface have been
investigated. The results of these load tests are compared
with theoretical estimates based on the concept of the
effective embedment depth of equivalent rigid piles for
ultimate and elastic case. Reasonable agreement has been
found between the observed and the predicted behavior
of flexible piles.
From the above literature, lack in the knowledge
about the behavior of pile under inclined loads near
ground slope was noted. Therefore, the main objective of
this paper is use experimental model to study the
behavior of pile adjacent to a slope crest under inclined
loads.
2 MODEL DESCRIPTION
Vertical and lateral loads were conducted on the model
pile in a rectangular steel test tank with the size of 1000
mm (length) x 500 mm (width) x 700 mm (height). The
vertical edges of the tank were stiffened by using steel
angle sections. The inner faces of the tank were
graduated at 50 mm intervals to facilitate an accurate
preparation of the sand bed in layers. The front long side
was made of a 20 mm thick glass panel. The glass side
allows the sand to be seen during the preparation and to
