Section 1 - Point of Virtual Fixity
Ref.: [1]-Michael Tomlinson and John Woodward-Pile Design and Construction Practice-6
th
edition
1. Soil properties
Reference
Layer
Soil type
1
2
3
4
Silty CLAY, soft to very soft
Sandy CLAY, very stiff
Silty SAND, medium dense to
Sandy SILT, hard
5
Granite rock
Strength parameter
SPT
[blows]
Unit weight
[kN/m3]
-[deg.]
cu-[kN/m3]
0-4
16.5
16.5
18.5
18.0
28.5
30
30
-
53
20.5
-
250
4-20
20-50
>50
-
2. Pile properties
● Pile type
Steel pile
- Outside diameter
- Wall thickness
- Section of steel pile
- Moment of inertia of pile
- Elastic modulus of pile
Bored pile
- Diameter
- Section of bored pile
- Moment of inertia of pile
- Elastic modulus of pile
Composited Pile
D =
t =
As =
Is =
Es =
B
Ab
Ib
Eb
1000
20
0.0616
0.0074
2.1E+08
960
mm
mm
m2
m4
kN/m2
=
=
=
=
0.0417
3.8E+07
kN/m2
EA =
EI =
4.0E+07
3.1E+06
kN
kN.m2
0.724
mm
m2
m4
Composited Pile
A - section area of pile
I - moment of inertia of pile
3. Virtual fixity point estimation method
● The equivalent fix - end column of pile:
Lu = Le = e + zf
Where:
e - free length of pile, m
zf - depth of fixity point, m
● For normally consolidated clays, granular soils
silt and peat:
zf = 1.8 T
1/5
T = (EI/nh)