Title: GSA 8'4 Piled Raft Analysis
1GSA 8.4 Piled Raft Analysis
2Piled-raft analysis
- The view of piled-raft plus soil model
3Piled-raft analysis
- The view of piled-raft model plus loadings
4How the pile-soil interaction works
- Schematic view of how piled-raft analysis works
5How the pile-soil interaction works
- Basic idea of GSA pile-soil interaction
- The plasticity of the soil immediately around the
pile are modelled by nonlinear springs. The
forces in the nonlinear springs are dependent on
the relative displacements of the pile and soil
at the same points (pile locations) - This approach is also used by other pile-soil
interaction programs such as SPLINTER - This approach is being considered as industry
standard for this type of analysis
6How the pile-soil interaction works
- Every nodes on the piles are connected by 3
nonlinear springs to represent the soil
non-linear behaviour immediately around the piles
in the 3 directions. - The non-linear springs are then attached to the
ground (soil) that is still considered as elastic
media and the settlements are calculated using
Mindlin method
Non-linear springs
A node on pile
Representing soil and they all coincide with the
pile node
7How the pile-soil interaction works
- The forces in the non-linear springs (the
pile-soil interaction force) are
Ax, Ay Az are the interaction area for the
nodes cx, cy cz are the interaction
coefficients (see next slide) fx fy are the
soil contact strengths in x y directions fz is
the soil shear strength between pile and soil
8How the pile-soil interaction works
- A section of pile represented by a pile node
tz
Ax ByH Ay BxH Az pH 2H(BxBy)
sx
tz
H
sy
By
Bx
9How the pile-soil interaction works
c
1.0
dx/By etc
dx, dy dz are the differences of displacements
between pile and soil in x, y z directions at
the same points
-1.0
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