2698
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
5.2. The lateral resistance factor
CONCLUSION
Equation 7 shows that the lateral soil resistance around a rigid
pile is greater than the one around a flexible pile and it increases
with the pile flexural stiffness and decreases with the embedded
length of the pile. For example, in case of a homogeneous sandy
soil, combining equations 7 and 8 gives:
The analysis of several full-scale lateral loading tests carried out
on instrumented piles in a variety of soils led to the definition of
hyperbolic P-Y curve whose parameters are correlated with the
PMT data.
2
3
2
B
D
K
K
p
(18)
It was shown the lateral soil reaction modulus and the lateral
soil resistance were correlated to the lateral pile/soil stiffness
ratio and the parameters measured during the PMT test (PMT
modulus and soil limit pressure).
A step-by-step methodology was presented to define the
parameters of P-Y curves for single pile under lateral loading in
multi-layered soils.
In contrast with K
E
, K
p
decreases however with the pile
slenderness ratio and increases with the pile/soil
compressibility.
5.3. Concept of the critical deflection
As illustrated by figure 1, the critical deflection Y
c
corresponds
to the intercept of the initial linear portion with a slope equal to
E
ti
, and the horizontal asymptote corresponding to the lateral
resistance P
u
. Y
c
is therefore defined as the threshold of large
lateral deflections of the pile section and of full mobilisation of
the lateral soil resistance according to the elastic plastic scheme
of the P–Y curve. Based on Equations (6) and (7), the ratio Y
c
/B
may be expressed by the following function of K
R
and the PMT
parameters measured in sand:
The proposed method of construction of P-Y curves was
validated by predicting the load-deflection response of single
piles laterally loaded in a variety of soils. The comparison of the
predicted pile deflections with the measured ones showed very
good predictive capability of the proposed pile/soil stiffness
dependant P-Y curves method.
REFERENCES
Baguelin F., Jézéquel J-F., Shields D-H.
The pressuremeter and
foundation engineering
, Series on rock and soil mechanics, Vol. 2
(1974/77), N° 4, 1
st
edition, 1978 Trans Tech Publications,
Germany, 615 p.
Bouafia A and Garnier J, 1991. Experimental study of P-Y curves for
piles in sand., Proceedings of the 1
st
international conference
CENTRIFUGE’91, Boulder, Colorado, 13-14 Juin 1991, pp 261-
268, A A Balkema.
M
L
R
c
E
pK
B
Y
*
9
(19)
Bouafia A. 2005. Evaluation of the Lateral Load-Deflection Behaviour
of Single Piles from the Pressuremeter Test Data, Proceedings of
the International Symposium on Pressuremeters ISP-05, Vol. 1, pp :
433-446, ISBN: 2-85978-417-9, Presses ENPC, August, 22-24,
2005, Paris.
and in clay by:
Bouafia A and Lachenani A. 2005. Analysis of P-Y Curves for Single
Piles from the Prebored Pressuremeter, Proceedings of the 16
th
International Conference on Soil Mechanics and Geotechnical
Engineering, September 12-16, 2005, Osaka, Japan, pp : 1955-
1958, ISBN: 978-90-5966-027-4.
M
L R
c
E
p K
B
Y
*
84.1
)
3.0(
(20)
Bouafia A. 2007. Single piles under horizontal loads-Determination of
the P-Y Curves from the prebored pressuremeter,
International
Journal of Geotechnical and Geological Engineering
, Springer-
Verlag, ISSN: 0960-3182, Vol. 25, pp: 283-301.
It is to be noted from equation 5 that the critical deflection Y
c
corresponds to half the limit lateral reaction in the hyperpoblic
formulation, say to a factor of safety of 2, and to all the limit lateral
reaction in the elastic plastic formulation.
Equations (19) and (20) provide simple and useful tool to estimate the
threshold of large lateral load-deflection behaviour.
Gambin, M. 1979. Calculation of foundations subjected to horizontal
forces using pressuremeter data,
Sols-Soils
N° 30/31, pp 17-59.
Garassino A. 1976. Soil modulus for laterally loaded piles,
Proceedings of the 4
th
European Conference on Soil Mechanics and
Foundations Engineering, Vienna, 1976.
Georgiadis M. Anagnastopoulos C., Saflekou S. 1992. Centrifugal
testing of laterally loaded piles,
Canadian Geotechnical Journal
,
No. 259, pp 208-216.
Hadjadji T., Frank R. and Degny E. 2002. Analyse du comportement
expérimental de pieux sous chargements horizontaux (in French),
Rapport de recherche série Géotechnique et Risques Naturels no.
GT-74, mai 2002, 303 p.
Moussard H. and Kersale J.-F. 2011. Etude expérimentale du
comportement d'un pieu isolé sous l'effet de sollicitations
horizontales de freinage et de démarrage de circulations ferroviaires
(in French),
Revue Française de Géotechnique
No. 134-135, 1
e
-2
e
trimestres 2011, pp 87-98.
Reese L C. 1971. The analysis of piles under lateral loading,
Proceedings of the Symposium Interaction structure-Foundation,
University of Birmingham, 1971.
Figure 4. Comparison of predicted and measured deflections in multi-
layered soil
