Geosynthetics International: Vol. 9, No. 1, 2002

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Technical Paper by A. Sawicki and K. Kazimierowicz-Frankowska

INFLUENCE OF STRAIN RATE ON THE LOAD-STRAIN CHARACTERISTICS OF GEOSYNTHETICS

ABSTRACT: Experimental results dealing with the influence of strain rate on the
load-strain characteristics of five different geosynthetics are presented and discussed,
including the load-strain curves and the strength of these materials. Theoretical and
empirical formulae are proposed to describe the observed behaviour of the geosynthetics
investigated. Particular attention is devoted to complex loading histories, for example,
loading at a constant strain rate followed by creep or stress relaxation and then
subsequent loading at the same strain rate. Such loading programmes reveal interesting
features of the geosynthetics’ behaviour, which can be designated as the isotach properties.
This problem is discussed in detail and a simple method of describing these
properties is proposed.

KEYWORDS: Geosynthetic, Load-strain characteristic, Strength, Creep, Stress
relaxation, Isotach property.

AUTHORS: A. Sawicki, Professor, and K. Kazimierowicz-Frankowska, Assistant
Professor, Institute of Hydroengineering, IBW PAN, ul. Koscierska 7, 80-953 Gdansk-
Oliwa, Poland, Tel: 48/58-552 20 11, Telefax: 48/58-552-42-11, E-mail: as@ibwpan.
gda.pl.

DATE: Original manuscript submitted 27 August 2001, revised version received 1
February 2002, and accepted 12 February 2002. Discussion open until 1 October 2002.

REFERENCE: Sawicki, A. and Kazimierowicz-Frankowska, K., 2002, “Influence of
Strain Rate on the Load-Strain Characteristics of Geosynthetics”, Geosynthetics International,
Vol. 9, No. 1, pp. 1-19.

Technical Paper by J.D. Frost, T.E. Zettler, J.T. DeJong, S.W. Lee, and S. Kagbo

STRAIN INDUCED CHANGES IN GEOMEMBRANE SURFACE TOPOGRAPHY

ABSTRACT: Textured geomembranes are commonly used in field applications to
increase the strength of geomembrane-soil and geomembrane-geosynthetic interfaces.
Under normal operating conditions, geomembranes within landfill liner systems are
subjected to both multiaxial and uniaxial strains induced by anchorage in trenches, differential
settlements, and thermal changes. The existence of strain may alter the
geomembrane surface, thereby affecting the strength of the interface. This paper presents
the results of an investigation into changes in surface topography of geomembranes
subjected to uniaxial strain. An integrated strain profilometer device was
developed to permit quantification of geomembrane surfaces while they were subjected
to strain. Geomembranes manufactured using various texturing processes were
subjected to increasing uniaxial strain levels ranging from 1 to 25%. Results show that
the effect of strain on the surface topography is dependent on the geomembrane manufacturing
process. The implications of changes in surface topography are linked to
potential changes in the interface strength.

KEYWORDS: Geomembrane, Strain, Surface roughness, Interface strength.

AUTHORS: J.D. Frost, Professor, School of Civil and Environmental Engineering,
Georgia Institute of Technology, Atlanta, Georgia 30332-0355, USA, Telephone: 1/
404-894-2280, Telefax: 1/404-894-2281, E-mail: david.frost@ce.gatech.edu; T.E. Zettler,
Staff Engineer, GeoSyntec Consultants, 1100 Lake Hearn Drive, Suite 200,
Atlanta, Georgia, 30342-1523, USA, Telephone: 1/404-705-9500, Telefax 1/404-705-
9400, E-mail: zettler@geosyntec.com; J.T. DeJong, Assistant Professor, Department
of Civil and Environmental Engineering, University of Massachusetts, Amherst, Massachusetts
01003, USA, Telephone: 1/413-545-2639, Telefax: 1/413-545-4525, Email:
dejong@ecs.umass.edu; S.W. Lee, Senior Researcher, Civil Engineering
Research Division, Korea Institute of Construction Technology, Ilsan, Koyang,
Kyunggi, 411-712, Korea, Telephone: 82/31-910-0230, Telefax: 82/31-910-0211, Email:
slee@kict.re.kr; and S. Kagbo, formerly Undergraduate Research Assistant,
Georgia Institute of Technology, Atlanta, Georgia 30332-0355, USA.

DATE: Original manuscript submitted 14 May 2001, and revised version received and
accepted 9 November 2001. Discussion open until 1 October 2002.

REFERENCE: J.D. Frost, T.E. Zettler, J.T. DeJong, S.W. Lee, and S. Kagbo, 2002,
“ Strain Induced Changes in Geomembrane Surface Topography”, Geosynthetics International,
Vol. 9, No. 1, pp. 21-40.

Technical Paper by A.H. Aydilek and T.B. Edil

FILTRATION PERFORMANCE OF WOVEN GEOTEXTILES WITH WASTEWATER TREATMENT SLUDGE

ABSTRACT: Capping of contaminated soft sediments and sludges for in situ containment
provides an efficient remediation alternative. Capping design typically involves the
use of geosynthetics for multiple functions, e.g., reinforcement, separation, and filtration.
Filtration performance becomes a decisive factor for proper long-term performance of
a cap. Because of multiple functions required, woven geotextiles are often the choice geosynthetic
in such applications. A research program concerning the filtration behavior of
contaminated wastewater treatment sludges was conducted. The laboratory portion of the
program included a series of filtration tests with different woven geotextiles. Filtration
performance of the sludge-woven geotextile systems was also observed in field test cells.
Geotextile samples were exhumed from the cells after exposure and analyzed in the laboratory.
The results indicate that the sludges can be filtered using woven geotextiles and
the selection of a proper filter can be made on the basis of geotextile pore structure parameters,
i.e. percent open area and pore opening size distribution. The standard gradient ratio
test did not always reflect the filtration performance and, therefore, other clogging ratios
need to be considered. A commonly used geotextile pore opening size-to-soil particle
ratio in the existing filter criteria, O95 /D85, did not predict the filtration behavior displayed
by the sludge; however, another ratio, O50 /D50, showed general correlation to
clogging and retention.

KEYWORDS: Sludge, Filtration, Woven geotextile, Gradient ratio test, Filter press
test, Image analysis.

AUTHORS: A.H. Aydilek, Assistant Professor, University of Maryland, 1163 Glenn
Martin Hall, Department of Civil and Environmental Engineering, University of Maryland,
College Park, Maryland 20742, USA, Telephone: 1/301-314-2692, Telefax: 1/
301-405-2585, E-mail: aydilek@eng.umd.edu; and T.B. Edil, Professor, Department
of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison,
Wisconsin, 53706, USA, Telephone: 1/608-262-3225, Telefax: 1/608-263-2453, Email:
edil@engr.wisc.edu.

DATE: Original manuscript submitted 25 August 2001, and revised version received
and accepted 9 April 2002. Discussion open until 1 October 2002.

REFERENCE: Aydilek, A.H. and Edil, T.B., “Filtration Performance of Woven Geotextiles
with Wastewater Treatment Sludge”, Geosynthetics International, Vol. 9, No.
1, pp. 41-69.

Technical Paper by N. Abu-Hejleh, J.G. Zornberg, T. Wang, and J. Watcharamonthein

MONITORED DISPLACEMENTS OF UNIQUE GEOSYNTHETIC-REINFORCED
SOIL BRIDGE ABUTMENTS

ABSTRACT: A geosynthetic-reinforced soil (GRS) system was constructed to support
the shallow footings of a two-span bridge and the approaching roadway structures.
Construction of this system, the Founders/Meadows bridge abutments, was
completed in 1999 near Denver, Colorado, USA. This unique system was selected with
the objectives of alleviating the “bump at the bridge” problem often noticed when
using traditional deep foundations, allowing for a small construction working area, and
facilitating construction in stages. The primary focus of the paper is to evaluate the
deformation response of this structure under service loads based on displacement data
collected through surveying, inclinometer, strain gages, and digital road profiler. The
overall short- and long-term performance of the Founders/Meadows structure was
excellent, suggesting that GRS walls are a viable alternative to support both bridge and
approaching roadway structures.

KEYWORDS: Soil Reinforcement, Bridge abutment, Field monitoring, Geogrid,
Instrumentation.

AUTHORS: N. Abu-Hejleh, Geotechnical Research Engineer, Colorado Department
of Transportation, 4201 East Arkansas Ave., Denver, Colorado 80222, USA, Telephone:
1/303-757-9522, Telefax: 1/303-757-9974, E-mail: Naser.Abu-Hejleh@dot.state.co.us;
J.G. Zornberg, Assistant Professor, Department of Civil, Environmental and Architectural
Engineering, University of Colorado at Boulder, Campus Box 428, Boulder, Colorado
80309-0428, USA, Telephone: 1/303-492-4699, Telefax:1/303-492-7317, E-mail:
zornberg@colorado.edu; T. Wang, Bridge Design Engineer, Colorado Department of
Transportation, 4201 East Arkansas Ave., Denver, Colorado 80222, USA, Telephone:
1/303-512-4072, Telefax: 1/303-757 9974, E-mail: ShingChun.Wang@dot.state.co.us;
J. Watcharamonthein, Graduate Student, Department of Civil, Environmental and Architectural
Engineering, U. of Colorado at Boulder, Campus Box 428, Boulder, Colorado
80309-0428, USA, E-mail: watchara@colorado.edu.

DATE: Original manuscript submitted 4 April 2001, revised version received 28
February 2002, and accepted 7 April 2002. Discussion open until 1 October 2002.

REFERENCE: Abu-Hejleh, N., Zornberg, J.G., Wang, T. and Watcharamonthein, J.,
2002, “Monitored Displacements of Unique Geosynthetic-Reinforced Soil Bridge
Abutments”, Geosynthetics International, Vol. 9, No. 1, pp. 71-95.