3452
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
а)
h=700
1/3h 1/3h 1/3h
1000
1
5
4
2
b)
1500
710
1500
800
100
50
50
5
1
3
4
К1
К5
К2
К3,4
Figure 2. Large-scale models of combined massive and plate
foundations: a – the plate is on the top of foundation, b – the plate is at
the bottom of foundation. 1 – block, 2 – lower plate, 3 – upper plate, 4 –
soil, 5 – vibrator.
The tests were performed on the silty clay with unit weight
19.7 KN/m
3
, natural water content 0.22, voids ratio 0.85,
Young’s modulus 10 MPa. The block was 1 m high with the
area of its foot equal 1m
2
. The plates thickness was h=0.05m
and h=0.1m. The area of the plates was F=2.13 m
2
and F=4.5
m
2
. The foundations were placed at the centre of a hole
excavated to the desired depth. Cyclic load was applied 12.7 –
25.4 KN under frequency 50 Hz. The amplitude-frequency
responses of the combined massive and plate foundations under
horizontal and vertical periodic loadings are shown in Figures 3
and 4.
a)
0
50
100
150
200
250
300
350
8 12 16 20 24 28 32 36 40 44 48 52 56
А,mkm
f,Hz
1
2 4
3
5
b)
0
10
20
30
40
50
60
70
80
f 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54
А,mkm
f,Нz
1
3
2
4
5
Figure 3. Amplitude-frequency responses of the combined massive and
plate foundations with the plate on the top of the foundations: a –
horizontal periodic load, b – vertical periodic load, 1 – amplitude-
frequency response of the block, 2 – F=2.13, h=0.05, 3 – F=4.5, h=0.05,
4 – F=2.13m, h=0.1, 5 – F=4.5m, h=0.1m.
a)
0
50
100
150
200
250
300
350
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52
А,mkm
f,Hz
1
2
3
4
5
b)
0
50
100
150
200
250
300
350
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52
А,mkm
f,Hz
1
2
3
4
5
Figure 4. Amplitude-frequency responses of the combined massive and
plate foundations with the plate at the bottom of foundations: a –,
horizontal periodic load b - vertical periodic load, 1 – the amplitude-
frequency response of the block, 2 – F=2.13, h=0.05, 3 – F=4.5, h=0.05,
4 – F=2.13m, h=0.1, 5 – F=4.5m, h=0.1m.
The comparison of the amplitude-frequency responses of the
combined massive plate foundations enable to evaluate
influence of the dimension of plates on responses of foundation.
We note that the vibration amplitude decreases half as much
with increasing of the plate area twice as many. The plate
thickness has less effect on the responses of foundation. It was
experimentally determinate, that the effect of top plates was
bigger under horizontal dynamic loading and the effect of
bottom plates was bigger under vertical dynamic loading.
A thin plate on the soil can significantly reduce the vibration
level of the block foundation. Figures 5 and 6 present the results
of such large-scale field test. Responses of the deepened block-
type foundation with dimension 1m x 1m x1m became quite
different after attaching a thin plate lying on the soil. So
resonance frequencies became 42%-64% higher. As a result the
high-frequency vibration amplitude decreased 3 – 4 times.
0
20
40
60
80
100
120
140
160
180
200
8 12 16 20 24 28 32 36 40 44 48 52 56
А,mkm
f,Hz
1
2
Figure 5. The amplitude-frequency responses of the block-type
foundations under horizontal periodic loading: 1 – the plate with area
8m
2
is on the top of foundation, 2 – no plate.
