1072
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
movements. The modulus of elasticity under saturated
condition, E
sat
= 750 kPa, was suggested based on the results of
the conventional oedometer tests conducted by Vu (2003) on
Regina expansive clay. The soil movement was predicted as a
function of time and depth. Due to limitations of space, the soil
movement variations are not provided in this paper. Both shrink
and swell behavior were observed in the period of the study.
The vertical soil movement has a strong correlation with the
predicted suction values. As anticipated, no vertical movement
of the soil was observed below the active zone. The vertical soil
movements estimated in this study were in reasonable
agreement with the results of Ito and Hu (2011), clearly
responding to climatic trends and infiltration events. Figure 5
provides a comparison between the vertical soil movements
estimated using the MEBM and Ito and Hu (2011) method at
different depths and times. The agreement between the results
of two methods is reasonable. Some differences observed can be
attributed to the differences in predicted soil suction profiles
using different methods. This may be also due to the governing
equations which were different for both the methods used for
estimating the vertical movement.
Time (days)
0
100
200
300
Suction (kPa)
0
500
1000
1500
2000
2500
3000
3500
Predicted suction ( Ito and Hu 2011 )
Predicted suction ( MEBM )
9 m
0 m
2 m
6 m
Figure 4. Soil suction changes with respect to time and depth
Figure 5. Comparison of the vertical soil movement estimated using the
MEBM and Ito and Ho (2011) method
5 CONCLUSIONS
Verification of the Modulus of Elasticity Based Method
(MEBM) for predicting the vertical soil movements over time
was accomplished in this paper using the numerical modeling
results of Ito and Hu (2011) for a Regina test site for a period of
one year. The changes in suctions due to alternate dry and wet
conditions were estimated using VADSOE/W. The soil
movements induced by the changes in suction were calculated
using the volume change constitutive relationship for
unsaturated soils.
The results of the study suggest that the MEBM is a simple
approach that can be used with reasonable degree of confidence
for predicting the vertical movements of unsaturated expansive
soils considering all the environmental factors. The results of
the study presented in this paper and three other case studies
that were reported earlier in the literature (Vanapalli and Adem
2012, 2013, and Adem and Vanapalli 2013) are encouraging for
extending the MEBM in engineering practice for rational design
purposes of both the sub and superstructures constructed in or
on expansive soils.
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Vertical movement (Ito and Hu 2011), mm
-1
0
1
2
3
4
5
Vertical movement (MEBM), mm
-1
0
1
2
3
4
5
0 m depth
0.5 m depth