Why does Repute incorporate PGroupN?
is a leading-edge computer program for the analysis and design
of pile groups, developed by Dr Francesco
Basile of Halcrow Group/Geomarc.
Key features - including full continuum solution, multi-layered
soil profiles and soil nonlinearity effects - make PGroupN the
most powerful tool to design pile groups in a rigorous yet cost-effective
There are many advantages in using PGroupN for pile group analysis
and design, including:
The PGroupN analysis is the most rigorous of the pile-group
design programs currently available. It is based on a complete
boundary element (BEM) solution of the soil continuum, thereby
overcoming the approximations which occur with the traditional
interaction factor approach. Use of the above methodology leads
to a more realistic prediction of the deformation behaviour and
load distribution of the individual piles of the group. Inclusion
of soil nonlinearity effects avoids exaggeration of pile stresses
at group extremities predicted by linear elastic models, and reduces
consequent high loads and moments. It has been shown that, even
at typical working load levels, this reduction is significant.
These aspects are of basic importance in practice and offer the
prospect of tangible improvements in design procedures and worthwhile
savings in construction costs.
Speed of use
One of the main features of PGroupN is its capability to provide
a complete 3D non-linear BEM solution of the soil continuum while
retaining a computationally efficient code. This represents a
considerable advantage over similar BEM solutions (eg PGroup)
which are limited by the large amount of computing time required
to analyse practical pile group problems. In principle, a complete
three-dimensional analysis of a pile group can be carried out
by finite element or finite difference analyses; however, the
complexity and high computational costs involved preclude the
ruotine use of such techniques in design (particularly if non-linear
soil behaviour is to be considered).
The development and testing of PGroupN is part of an eight years’
research programme led by Dr Francesco Basile.
Contributors include the late Dr Ken Fleming of Skanska Cementation
Selected publications on
The ability of PGroupN to deal with multilayered soil profiles
gives the designer an invaluable tool resulting in a more realistic
picture of the group deformation response and the load distribution
between the piles. Other facilities including variable moduli,
lengths, and diameters per each pile enhance the flexibility of
the program and offer the designer a comprehensive tool for the
analysis of a wide range of practical problems.
Ease of use
The amount of input data required by PGroupN is minimal. The
choice of soil parameters is simple and direct: for a linear analysis,
it is only necessary to define two soil parameters whose physical
interpretation is clear, i.e. the soil modulus and the Poisson’s
ratio. If the effects of soil non-linearity are considered, the
strength properties of the soil need also to be specified, i.e.
the undrained shear strength for cohesive soils and the angle
of friction for cohesionless soils. These parameters are routinely
measured in soils investigation. This aspect represents a significant
advantage over load-transfer or subgrade reaction approaches (e.g.
the t-z and p-y curve methods) which are based on empirical parameters
which can only be backfigured from the results of pile load tests.