2861
Technical Committee 212 /
Comité technique 212
Table 1. Result of pile test.
Pile parameters
Site
(Pile)
Ø, m
L, m
Head
level, m
Jack
level, m
Max
load, MN
Max
displacement
head/tip, mm
Side resistance determination
method
Pile side
resistance
MN/m
2
3(1)
1,2
28
113
86,1
20
3,1/1,5
D
1,20
3(2)
1,2
28
113
86,1
20
1,8/2,5
D
1,20
4(1)
1,2
28,6
110,4
87,4
26,5
4,1/1,7
D
-
4(2)
1,2
28,0
110,4
84,4
24,5
3,4/1,4
D
-
11(1)
1,2
22,6
104,5
85
20,00
1,8/2,1
D
1,30
11(2)
1,2
22,6
104,5
85
16,50
1,0/1,5
D
1,80
12
1,5
10,5
85,1
81,6
33,30
3,2/7,5
D,F( 4)
2,55 (1,55)*
13А
1,2
27
109
89
33,3
6,1/3
F(6)
2,00
13Б
1,2
29,7
109
83,7
25,13
17/6
F(3)
2,20
14 (1)
1,5
19,2
103,2
88,4
33,33
8/65
D
2,00
14 (2)
1,5
19,2
103,2
92,6
33,33
16/4
D
1,90
15 (1)
1,5
20,4
103,8
93,4
1350
4/150
D
200
15 (2)
1,5
19,4
103,8
86,4
3333
10/10
D
200
16(1)
1,5
24,3
118,5
114
3000
8,3**
F(19)
33
16(2)
1,5
24,3
118,5
114
3200
7,2**
F(19)
36
*2,55(1,55) – values with no brackets were determined from tensometer data analysis , in brackets from fragment test data;** top-down fragments
tests ; D, F – side resistance was determined as per equation 1 and from pile fragment test data ; F(4) – fragment length m.
In order to separate side and tip resistances the pile consisted
of two parts: inside part 1 (630 mm external diam.) and outer
part 2 (1500 and 820 mm ring diam.). The hollow space be-
tween the pile segments (3) was filled with elastic material to let
the parts to freely slide against each
other. The interior part (1) was
connected with a stiff plate (4). In
order to isolate the pile exterior top
(2) from the soil mass an external
casing tube was installed on the top
(5). The loaded system included
two steel box cross beams (Figure
7), connected with service piles,
used as anchors.
The tests were started by load
application to the interior part of the
pile (1) and through it to the plate
(4) (pile tip test).
Then the set-up was adjusted to
step wise load application to the
exterior part of the pile (2), and pile
side resistance was determined.
Figure 7. Loading set-up
The initial plate test and elastic
spacers between pile parts prevent
data distortion in the pile exterior
side test.
The test results (Figure 8,9)
show that the central part of the
plate displacement largely exceeds
that of the pile-shell.
Figure 6. Loading set-up
The pile tip resistance for equal displacements was one or-
der of magnitude less than that of the side resistance and several
orders of magnitudes less than the analytical value. This fact
shows presence of mud on the borehole bottom, which could not
be removed during drilling operations.
Soil resistance below pile tip at other sites demonstrated its
strong dependence on the quality of the bottom face and on the
quality of special operations (soil grouting), e.g. on site 4 grout-
ing was done to 5 m below the pile tip.
1 – loading, 2 - unloading
This shows the necessity for extra operations to clean and to
compact the bottom, e.g. by grouting the soil under pile tip, by
compacting the bottom, e.g. by ramming broken stone or stiff
concrete into the bottom, etc. (Petrukhin et al, 2011).
Figure. 8. Pile tip test diagram
