3450
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Table 2. Tank 5. Settlement measured after 4.5 and 10 years and
calculated for 4.5 and 10 years.
7 REFERENCES
Alonso, E.E., Gens, A. y Lloret, A. (2000).
Precompresión design for
secondary settlement reduction
. Geotechnique 50(6), 645-654.
Point
4.5 years
Measured
mm
4.5 years
Calculated
mm
10 years
Measured
mm
10 years
Calculated
mm
26
24
26
30
36
17
41
41
45
52
6
33
31
40
42
27
46
46
62
65
28
57
56
77
79
16
128
128
158
171
8
84
76
117
105
29
61
74
81
104
Alonso, E.E., (2004).
Deformabilidad a largo plazo de suelos
precargados.
8º Simposio Nacional de la S.E.M.S.I.G., Valencia,
págs 245 a 250.
Alonso, E.S., Lloret, A., Gens, A. y M. Salvadó (2001).
Overconsolidation effects on secondary compresión rates
. Proc.
15
th
International Conference on Soil Mechanics & Geotechnical
Engineering.Istambul, 1:5-8.
Dapena, E., Román, E., San Salvador, J. (2005). Long term settlement
of foundations made of 195 x 147 m slabs built on a layer of fluvial
sediment.
Proc. 16
th
Int. Conf. Soil Mech. & Geotech. Engng. 1,
1033-1036.
Dapena, E., Román, F. (2007).
Differential settlement measured over
five years in major-scale shallow foundations on a preloaded 20 m.
thick silty alluvial layer.
Proceedings of the 14
th
European
Conference on Soil Mechanics and Geotechnical Engineering.
Madrid. Vol. 2 pp.451-456
Jamiolkowsky, M., Lancellota, R. y Wolski, W. (1983).
Precompression
and speeding up consolidation.
General Report. Proc. Europ. Conf.
Soil Mech. Found. Engng. Helsinki, 3:1201-1226.
For the 6 years prior to construction of the phase 2
biodigesters, a uniform preload equal to that which would be
transferred by the biodigesters was kept on the entire area.
However, when they were constructed, the initial design was
modified and the load transferred was 0.14 kg/cm
2
greater than
the load of the soil removed.
Johnson, S.J., (1970).
Precompression for improving foundations soils
J. Soil
Mech
. Found. Div. ASCE, 96(1): 111-114.
Koutsoflas, DC., Foott, R. y Hadleft, L.D. (1987).
Geotechnical
investigations offshore Hong Kong
, J. Geotech. Enging. Dic.
ASCE, 113(2): 87-105.
Magnan, J.P. (1994).
Methods to reduce the settlement of embankments
on soft clay, a review,
In: Vertical and horizontal displacements.
ASCE. Geotech. Special Pub. 40(1): 77-91
10 years after the biodigesters were constructed, tanks 1 and
4 have practically stabilized, as settlement is less than 50 mm in
these areas. Tanks 2 and 5 are the areas with the greatest
settlement, reaching 218 mm at tank 2 and 158 mm at tank 5,
without any problems with the operation of the tanks having
been detected. This settlement can be divided into zones, as
shown in Figure 2.
Mitchell, J.M. (1981).
Soil Improvement.
State of the art report. Proc.
10
th
I
nt. Conf. Soil Mech. And Found. Engng. Stockholm. 2:509-
565.
Stamatopoulos, A.C. y Kotzias, P.C. (1983).
Settlement-time predictions
in preloading
. J. Geotech. Engng. Div. ASCE, 109(6): 802-820.
Yu, K.P. y Frizzi, R.P. (1994).
Preloading organic soils to limit future
settlements
.
Vertical and horizontal displacements of foundations
and embankments, ASCE. Geotech. Special Pub. 40(1): 476-490.
The settlement which occurs based on time fits the model S
= a
a
t
+b, where t
a
is the time in years where the tank has
been full.
Coefficient “a” is related to the rate of settlement and its
distribution is similar to the settlement values as shown in
Figure 4. Thus, at tanks 1 and 4, where the least settlement has
occurred, the value of “a” is less than or equal to 5, while at the
center of tank 2, it is a
0.5-9
=58.9, and at the center of tank 5, it is
a
05-9
= 37.5.
By comparing the “a” values when the model is adjusted for
the period of time between 0.5 and 9 years, and the “a” values
when this period of time is between 8 and 10 years, it is
possible to observe that the settlement is stabilizing, particularly
in the areas with greater settlement.
