Axially Loaded Pile Analysis
This module has two independent sub modules:

(a) **Axial pile deformation analysis**

Pile is modelled as an elastic structural member having
the cross section of the pile and the elastic properties of the
pile material. The soil support providing the shaft friction is
modelled by a set of side springs based on t-z curves. The tip
resistance provided by the pile base the base is modelled by a
spring based on q-z curve.

The software supports both ‘Elastic Bi-linear’ and
‘Non-Linear’ approaches for modelling and any one of them can
be selected for analysis.

In the ‘Non-Linear’ approach, for the soil layer, based on the
t_{max} and q_{max} values calculated ,
non-linear t-z curves (interface shear stress- vertical pile
movement at that point) and q-z curve (bearing stress and toe
displacement) are developed based on API-2011 guidelines. In
the case of rock layers, using the tmax and qmax values, t-z
and q-z relationships are modelled by a bilinear elastic –
plastic curve based on the elastic modulus and Poisson ratio of
the rock layer.

In the ‘Elastic Bi-linear’ approach, for the soil layer, t-z
and q-z relationships are modelled by bilinear elastic –
plastic curves based on the elastic modulus, Poisson ratio ,t_{max}
and q_{max} for the layer.

The axial pile analysis follows a non-linear finite
element model using the axial rigidity of the pile and the
nonlinear soil support based on the t-z curves and q-z curve. .
The analysis uses an Iterative approach to achieve convergence.

The analysis provides displacement of the pile head under
a given load on the pile head, variation of axial load along
the pile length, and the load carried by the pile base.
Different loads applied on the pile head and the corresponding
head displacements provide the load displacement curve.

(b) **Generation of t-z and q-z curves**

Development of a set of t-z curves along the shaft length
and q-z curve at the pile base for compressive loading.
Multiple t-z curves are generated for each soil layer. The
curves can be based on ‘API-2000 RP’, ‘API-2011 RP GEO’ or
‘Elastic Method’ for sand and clay layers. API based methods,
also account for reduction in post peak adhesion in clay layers
through a factor R.