 |
|
 |
|
 |
Geocentrix Repute -
Intelligent pile design and analysis
3-pile group under general loading |
|
|
 |
|
 |
|
|
|
|
|
|
|
The following example [1] describes
a group of 3 piles under general loading conditions. Three types
of analysis are described:
- A simple statical method that ignores the presence
of soil and considers the pile group as a purely structural
system
- The equivalent-bent method that reduces the pile
group to a structural system but takes some account of the
effect of
the soil by determining equivalent free-standing lengths of the
piles
- Pile group programs that consider the presence of the
soil, including the interaction effects between the piles through
the soil, specifically Repute, DEFPIG, Piglet, and GEPAN [2]
The
3-pile group is subjected to a combination of axial load,
lateral load and moment. Results from the above methods are
compared
in Table 1 in which w3, u, and θ are the
vertical head displacement of Pile 3, the horizontal cap displacement
and the rotation
of the cap, respectively. Resulting loads and bending moments
at
the pile heads are also reported.
.png)
|
|
Results from Repute
The results from Repute are given
in the table below.
Comparison with benchmark
| Variable |
Equivalent Beam |
Statical analysis |
DEFPIG |
Piglet |
GEPAN |
Repute |
| V1 (kN) |
67.2 |
75.0 |
55.8 |
55.7 |
54.0 |
49.6 |
| V2 (kN) |
200.0 |
200.0 |
155.1 |
155.0 |
156.0 |
153.0 |
| V3 (kN) |
332.8 |
325.0 |
389.1 |
389.3 |
390.0 |
397.0 |
| H1 (kN) |
66.6 |
66.7 |
72.0 |
80.4 |
73.7 |
68.9 |
| H2 (kN) |
66.7 |
66.7 |
56.0 |
39.3 |
50.9 |
53.5 |
| H3 (kN) |
66.6 |
66.7 |
72.0 |
80.4 |
75.4 |
77.6 |
| M1 (kN) |
-6.2 |
0 |
-35.8 |
-42.0 |
-38.5 |
-41.5 |
| M2 (kN) |
-6.2 |
0 |
-28.5 |
-16.3 |
-26.1 |
-31.8 |
| M3 (kN) |
-6.2 |
0 |
-35.8 |
-42.0 |
-38.6 |
-44.0 |
| w3 (mm) |
17.5 |
n/a |
13.4 |
9.9 |
10.8 |
14.1 |
| u (mm) |
8.9 |
n/a |
11.6 |
11.4 |
10.5 |
11.5 |
| theta (rad) |
0.00581 |
n/a |
0.00242 |
0.00242 |
0.00241 |
0.00263 |
n/a = not available
|
Comments
There is a good agreement between
the solutions which consider pile-soil-pile interaction (even if with different
degrees of rigour), whereas the statical and equivalent-bent analyses give
quite different results, thereby showing the pitfall of attempting to model
a complex pile-soil system by means of a simple structural frame.
Reference
[1] Poulos H. G. & Davis, E. H. (1980). Pile foundation analysis
and design. Wiley, New York.
[2] Xu K. J. & Poulos H. G. (2000). General elastic analysis
of pile groups. Int. J. Numer. Anal. Meth.
Geomechs 24, 1109-1138.
Downloads
Repute
project for this example |
|
|
|
|
|
|
|
|
|
