10 Figure 6. Load-displacement of the raft-pile
system The maximum load values of the models are
represented in the Table 2. It shows that the maximum load of the raft is higher than the
group of pile. Further more, the maximum value of the raft-pile system is higher that the sum of
the piles and the plate. In the other words, the efficiency of the raft-pile system is more than
100 which is 130 for these tests compared to the sum of piles’ capacity. Even the plate
only gives small contribution to the total load max 15 , the load displacement of the pile is
similar to the plate compared to the piles’ one Figure 7.
Table 2. Resume of the results
Model : pile
1 + 2 group of pile plate
piles + plate
raft-pile P max.
unit 46,5 42,5 6,9
51,5 60,4
Ratio to pile 1+2
100 91 15 111
130 Disp. max
o.o1 mm 100 110 200
170 220
Figure 7. Load-displacement of the models If the efficiency of the raft-pile system is defined
as ratio of the system compared to the sum of the individual pile and the raft, the efficiency of
the raft-pile system , E
rp
, is written as: capacity
raft and
pile individual
the of
sum the
capacity pile
- raft
the E
rp
= Using the above equation, the efficiency of the
raft-pile system is:
117 51.5
60.4 E
rp
= =
which is greater than 100.
4.2. Results For 2x2 Concrete Pile-Raft System
The results of the tests are presented in the terms of load displacement curves as follows. figure 8,
9, 10 and 11 show the plot of load-displacement of the 4 single piles. the firs one gives the
maximum load of 20 unit of load, 20.8 for the second pile, 20.2 and 20.4 for the third and the
fourth piles respectively. The unit load is the value shown by the dial which is the unit equal
to about 0.2 kg. the maximum loads are reached at the displacement of 1.50 mm for pile 1 and 4,
and 1.40 mm for pile 2 and 3 respectively. The piles show similar behaviour in terms of non-
dimensionless load-displacement curves as presented in the figure 13. the load and the
displacement are in the term of the ratio of the maximum values.
10 20
30 40
50 60
70
100 200
300 disp. o.o1 mm
L oad
uni t
Pmax = 60.4
Dmax = 220
1 0 2 0
3 0 4 0
5 0 6 0
7 0
5 0 1 0 0
1 5 0 2 0 0
2 5 0 3 0 0
d is p . o . o 1 m m Lo
ad un
it
P 1 + P 2 + P l a t e r a f t - p i l e
P l a t e P 1 + P 2
P 49 7
P
Universitas Sumatera Utara
Novrial
11 Figure 8. Load-displacement of pile 1
Figure 9. Load-displacement of pile 2 Figure 10. Load-displacement of pile 3
Figure 10. Load-displacement of pile 3 Figure 11. Load-displacement of pile 4
The plot of load-displacement of the group of the pile 1, 2, 3 and 4 is shown in the figure 12.
the maximum load of the group is 76.4 unit reached at the displacement of 1.1 mm. The
maximum load is about 94 of the sum of the piles capacities. the value may be referred as the
efficiency of the group.
A similar behaviour of group and single piles in terms of load-displacement curves can be seen in
the figure 13. Figure 12. Load-displacement of the pile group
5 10
15 20
25 30
35 40
50 100
150 200
250
disp. o.o1 mm Load unit
Pmax = 6.9
Dmax = 200
5 10
15 20
25 30
50 100
150 200
250 disp. o.o1 mm
Load unit
Pmax = 20,2 Dmax = 140
5 10
15 20
25 30
35 40
50 100
150 200
250
disp. o.o1 mm Load unit
Pmax = 6.9
Dmax = 200
5 10
15 20
25 30
50 100
150 200
250 disp. o.o1 mm
Load unit
Pmax = 20,4 Dmax = 150
10 20
30 40
50 60
70 80
90
50 100
150 200
disp. o.o1 mm Load
unit
Pmax = 76,4 Dmax = 130
5 10
15 20
25 30
50 100
150 200
250 disp. o.o1 mm
Load unit Pmax = 20
Dmax = 150
5 10
15 20
25 30
35 40
50 100
150 200
250
disp. o.o1 mm Load unit
Pmax = 6.9
Dmax = 200
5 10
15 20
25 30
50 100
150 200
250 disp. o.o1 mm
Load unit
Pmax = 20,8 Dmax = 140
Universitas Sumatera Utara
12 Figure 13. Load-displacement of the pile group
and sum of pile 1, 2, 3 and 4 The test result in the terms of load displacement
curves for the plate and the raft-pile system are shown in the figure 14 and 15. the loading test of
the plate gives the maximum load of 36.0 and the 135.0 for the raft-pile system. The maximum
loads are reached at the displacement of 2.00 mm for the plate. for the raft-pile system, the
maximum load is reached at the displacement of 2.10 mm.
Figure 14. Load-displacement of the plate
Figure 15. Load-displacement of the raft-pile system
The maximum load values of the models are represented in the Table 3. It shows that the
maximum load of the raft is higher than the group of pile and the combinations of the group
and the single raft. Further more, the maximum value of the raft-pile system is higher that the
sum of the piles and the plate. In the other words, the efficiency of the raft-pile system is
more than 100 which is 167 for these tests. Even the plate only gives small contribution to
the total load 44 , the non-dimensional load displacement of the raft-pile system is similar to
the plate compared to the piles. Again, if the efficiency of the raft-pile system is
defined as ratio of the system compared to the sum of the individual pile and the raft, the
efficiency of the raft-pile system , E
rp
, is written as:
capacity raft
and pile
individual the
of sum
the capacity
pile -
raft the
E
rp
= Using the above equation, the efficiency of the
raft-pile system is:
125 108.4
135 E
rp
= =
which is more than 100.
10 20
30 40
50 60
70 80
90
50 100
150 200
disp. o.o1 mm Load unit
P1+2+3+4 Pile Group
Pg = 76.4 P
1234
= 81
5 10
15 20
25 30
35 40
45 50
75 150
225 300
disp. o.o1 mm Load unit
Pmax = 36.0 Dmax = 200
20 40
60 80
100 120
140 160
100 200
300 disp. o.o1 mm
L oad
un it
Pmax = 135
Dmax = 210
Universitas Sumatera Utara
Novrial
13
4.3. Load Capacity Of A Shallow Raft In Clay
