This is a test case from the PIGLET User Manual , which
compares analytical results with those obtained from model tests
in sand . It deals with a 2 x 3 pile group, with the end rows
of piles raked at 1 in 3 outwards from the pile cap.
The piles (533mm long, 12.7mm diameter, 0.8mm wall thickness) are spaced
at 127mm centres in the X-direction (Sx) and
at 75mm centres in the Y-direction (Sy). The piles'
equivalent solid Young's moduli are assumed to be 16.3GPa axially
and 28.9GPa laterally. The bottom of the pile cap is in contact
with the ground surface.
The sand has a shear modulus G = 4.2z MPa
z is the depth below the ground surface)
and Poisson's ratio = 0.25.
The loads applied to the pile cap are V = 222N, H = 138N, and M =
Results from Repute
|Click the thumbnail images below to see bar graphs
giving the results obtained from Repute, PIGLET, and the physical
Comparison with benchmark
The axial loads predicted by Repute are within 5% of those predicted by
PIGLET , which in turn differ from the measured loads  by
up to 12%.
The shear loads predicted by Repute are typically 10% different from those
predicted by PIGLET, which in turn are typically 15% less than
the measured loads.
The bending moments predicted by Repute are typically 13% higher than those
predicted by PIGLET, which in turn differ typically from the measured
moments by 6%.
The agreement between Repute, PIGLET, and Davisson and Salley's model tests
is remarkably good, given the different assumptions
made in the two methods of analysis [1, 3] and the inherent inaccuracies
in physical modelling.
Better agreement between PIGLET's predictions and
the measured results is expected because the shear modulus
adopted by Randolph  for the soil was backfigured
from test results for a single pile.
M. F. (1996). PIGLET analysis and design of pile groups, University
of Western Australia.
 Davisson, M.T. and Salley, J.R (1970). Model study of laterally
loaded piles. J. Soil Mechanics and Foundation Engineering Division,
American Society of Civil Engineers, vol 96, no SM5.
 Basile, F. (2003). Analysis and design of pile groups. In
Numerical Analysis and Modelling in Geomechanics (ed. J. W. Bull),
London, Chapter 10, pp 278-315.
project for this example.
Note: this project was created by importing
a PGroupN (PGN) data file. You cannot enter the data directly
into Repute, since the user interface only allows you to model
real-world (and not model) piles.