1946
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Figure 7. Effect of expansive soils on wall penetration depth.
Figure 8. Effect of expansive soils on wall bending moment.
4.3
Anchor force
The effect of expansive soils and potential swell pressure on
anchor force is presented in Figure 9. The results show that the
anchor force increases as the plasticity index of soil increases,
similar to the wall penetration depth and bending moments.
However, the presence of expansive soils has the most
significant effect on the anchor forces. This is because of the
fact that the anchor is located closer to the top of sheet pile wall
and the swell pressures are higher closer to the ground surface
due to more fluctuations in soil moisture content in this zone.
Within the range of parameters considered, an increase in the
anchor force can be as much as 240% (when plasticity index is
50%) compared to the condition where the wall is installed in
non-expansive soil.
5 SUMMARY AND CONCLUSIONS
The design of retaining walls usually specifies cohesionless
soils as a backfill material behind the wall, however, in-situ
retaining walls, such as anchored sheet pile walls, are installed
in existing soils. Expansive soils exist in many locations around
the world, and the design of anchored sheet pile walls needs to
consider the effect of soil swell pressures when these walls are
installed in these soils.
In this paper the effect of expansive soils and swell pressures
on anchored sheet pile walls, in terms of wall penetration depth,
wall bending moment, and anchor force were investigated. The
swell pressures were determined using the soil plasticity index,
based on earlier studies. For the cases studied and range of soil
properties considered, the analysis results show that the effect of
expansive soils on anchored sheet pile walls can be significant,
even if the soils at the site are low to marginally expansive. For
soils with the plasticity index of 50%, indicative of highly
expansive soils, and for wall geometry and soil conditions
considered during this study, the analysis results show that the
wall penetration depth increased 190%, wall bending moments
increased 170%, and anchor force increased 240%, compared
with the wall design when soils at the site are non-expansive.
The maximum increase was observed in the anchor force,
because higher swell pressures develop closer to the ground
surface due to the seasonal changes in moisture content. It
should be noted that the swell pressures determined using the
plasticity index values represent the maximum potential swell
pressures, i.e. upper limit, and these pressures may not develop
during each seasonal changes.
Figure 9. Effect of expansive soils on anchor force.
6 REFERENCES
Bilgin Ö. and Erten M.B. 2009. Analysis of anchored sheet pile wall
deformations.
Contemporary topics in ground modification,
problem soils, and geo-support (GSP 187). Proceedings,
International Foundation Congress & Equipment Expo 2009
,
Orlando, Florida, 137-144.
Day R.W. 1994. Performance of slab-on-grade foundations on
expansive soils.
Journal of Performance of Constructed Facilities
8
(2), 129-138.
Erzin Y. and Erol O. 2007. Swell pressure prediction by suction
methods.
Engineering Geology
92 (3-4), 133-145.
Marsh E.T. and Walsh R.K. 1996. Common causes of retaining-wall
distress: case study.
Journal of Performance of Constructed
Facilities
10 (1), 35-38.
Naval Facilities Engineering Command (NAVFAC) 1986.
Foundations
and earth structures, NAVFAC DM 7.02
, Alexandria, VA.
O’Neill M.W. and Poormoayed, N. 1980. Methodology for foundations
on expansive clays.
Journal of the Geotechnical Engineering
Division
106 (GT12), 1345-1367.
Potts D.M. and Fourie A.B. 1984. The behavior of a propped retaining
wall: Results of a numerical experiment.
Geotechnique
34 (3), 383-
404.
Rowe P.W. 1952. Anchored sheet-pile walls.
Proc.- Inst. Civ. Eng.
1
(1), 27-70.
Snethen D.R. 1980. Characterization of expansive soils using soil
suction data.
Proceedings of the 4th International Conference on
Expansive Soils
, Denver, Colorado, 54-75.
Thomas M.G., Puppala A.J., and Hoyos L.R. 2009. Influence of swell
pressure from expansive fill on retaining wall stability.
Contemporary topics in ground modification, problem soils, and
geo-support (GSP 187). Proceedings, International Foundation
Congress & Equipment Expo 2009
, Orlando, Florida, 590-597.
U.S. Army Corps of Engineers (USACE) 1983.
Foundations in
expansive soils
,
TM 5-818-7
, Washington, DC.
U.S. Army Corps of Engineers (USACE) 1994.
Design of sheet pile
walls
,
EM 1110-2-2504
, Washington, DC.
