Geosynthetics International: Vol. 9, No. 2, 2002

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Technical Paper by B. Chareyre, L. Briançon, and P. Villard

THEORETICAL VERSUS EXPERIMENTAL MODELING OF THE ANCHORAGE CAPACITY OF GEOTEXTILES IN TRENCHES

ABSTRACT: The behavior of the anchorage of geotextile sheets at the top of a slope
is a decisive factor when determining the dimensions of geosynthetic lining systems on
slopes. In order to optimize the geometry of the structures in question (to reduce the area
taken up by the anchorage at the top of the slope), anchorage solutions using trenches
of varying forms are sometimes used. Calculating the required dimensions of this
anchorage remains problematic. To improve knowledge of the behavior of anchor
trenches, experimental studies and numerical studies were developed. Full-scale pullout
tests were carried out on anchored geotextile sheets (run-out anchorage and anchor
trenches). Two types of soil were studied: sand and sandy silt. The numerical modeling
proposed was based on the Discrete Element Method (DEM). This method is particularly
well suited to the problem being addressed, for it enables consideration of major movements
and large-scale deformation of the soil (rotation, compression, and lifting) as well
as large displacements between the geotextile and the soil. Comparisons between the
experimental and numerical results provide practical conclusions concerning anchorage
mechanisms.

KEYWORDS: Anchorage, Trench, Geotextile, Experimentation, Discrete element
modeling, Granular material.

AUTHORS: B. Chareyre, Ph.D. Student, Lirigm, Université Joseph Fourier, 38041
Grenoble, Cedex 9, France, Telephone: 33/0476828080, Telefax: 33/0476828072, Email:
Bruno.chareyre@ujf-grenoble.fr; L. Briançon, Ph.D. Student, Cemagref, Groupement
de Bordeaux, 50–avenue de Verdun, 33612–Cestas Cedex, France, Telephone: 33/
0557890800, Telefax: 33/0557900801, E-mail: laurent.briancon@bordeaux.
cemagref.fr; and P. Villard, Assistant Professor, Lirigm, Université Joseph Fourier,
38041 Grenoble, Cedex 9, France, Telephone: 33/0476828052, Telefax: 33/
0476828070, E-mail: Pascal.villard@ujf-grenoble.fr.

DATE: Original manuscript submitted 19 December 2001, revised version received 28
January 2002, and accepted 1 February 2002. Discussion open until 1 February 2003.

REFERENCE: Chareyre, B., Briançon, L., and Villard, P., 2002, “Theoretical Versus
Experimental Modeling of the Anchorage Capacity of Geotextiles in Trenches”,
Geosynthetics International, Vol. 9, No. 2, pp. 97-123.

Technical Paper by S.K. Bhatia, J.L. Smith, D. Lake, and D. Walowsky

A TECHNICAL AND ECONOMIC EVALUATION OF GEOSYNTHETIC ROLLED EROSION CONTROL PRODUCTS IN HIGHWAY DRAINAGE CHANNELS

ABSTRACT: Historically, local village, town, and county highway departments have
relied heavily on the use of stone fill and rock riprap to line highway drainage channels.
These are often constructed without the benefit of design or the evaluation of alternatives,
because they have always been done this way. In September 1999, the Munro Road
reconstruction project was completed in Onondaga County, New York. As part of an erosion
and sediment control demonstration project, the drainage portion of the project was
redesigned using geosynthetic rolled erosion control products (RECPs) in lieu of stone
fill and rock riprap on almost 1,130 m of channel. The use of the RECPs saved approximately
$95,800 in construction costs and is expected to lower maintenance costs as well
as provide long-term protection against erosion. The overall purpose of the project was
to demonstrate to highway departments the functional and economical advantages of
using RECPs for these applications. This paper summarizes the design, construction, and
performance to date of seven of the ten different RECPs installed for the project.

KEYWORDS: Erosion control, turf reinforcement mat, erosion control blanket,
drainage channel.

AUTHORS: S.K. Bhatia, Professor, Department of Civil and Environmental Engineering,
Syracuse University, Syracuse, New York 13244, USA, Telephone: 1/315-443-
3352, Telefax: 1/315-443-1243, E-mail: skbhatia@mailbox.syr.edu; J.L. Smith,
Research Fellow, Department of Civil and Environmental Engineering, Syracuse University,
Syracuse, New York 13244, USA, Telephone: 1/315-443-2313, Telefax: 1/315-
443-1243, E-mail: jlsmit06@syr.edu; D. Lake, Engineering Specialist, New York State
Soil and Water Conservation Committee, Syracuse, New York, Telephone: 1/315-682-
1133, E-mail: dulac19@earthlink.net; and D. Walowsky, Civil Engineering Technician,
National Resources Conservation Service, Lafayette Field Office, Lafayette, New York,
Telephone: 1/315-677-4630, E-mail: david.walowsky@ny.usda.gov.

DATE: Original manuscript submitted 23 December 2001, revised version received 18
May 2002, and accepted 21 May 2002. Discussion open until 1 February 2003.

REFERENCE: Bhatia, S.K., Smith, J.L., Lake, D., and Walowsky, D., “A Technical
and Economic Evaluation of Geosynthetic Rolled Erosion Control Products in Highway
Drainage Channels”, Geosynthetics International, Vol. 9, No. 2, pp. 125-148.

Technical Paper by E.M. Palmeira, N.R. Lima, Jr., and L.G.R. Mello

INTERACTION BETWEEN SOILS AND GEOSYNTHETIC LAYERS IN LARGE-SCALE RAMP TESTS

ABSTRACT: Ramp tests can be used for the evaluation of bond strength between soils
and geosynthetics and between different layers of geosynthetics. This paper presents a
theoretical and experimental study on the use of this type of test to measure soil-geosynthetic
interface bond strength. Granular and cohesive soils and a wide range of geosynthetic
types were employed in the tests. Tests with one to three geosynthetic layers
were carried out with measurements of mobilised tensile loads. The results show the factors
that may affect test results, such as apparatus size, soil type, geosynthetic tensile
stiffness, and surface characteristics. Mechanisms of interface failure and of load transference
between different layers are also identified and discussed.

KEYWORDS: Geosynthetic, Ramp test, Lining, Interface strength, Interaction.

AUTHORS: E.M. Palmeira, Associate Professor, N.R. Lima, Jr., Master’s Student, and
L.G.R. Mello, Master’s Student, University of Brasilia, Department of Civil and Environmental
Engineering, Faculty of Technology, 70910-900 Brasilia, DF, Brazil, Tel: 55/
61-273 7313, Telefax: 55/61-273 4644, E-mail: palmeira@unb.br.

DATE: Original manuscript submitted 12 February 2002, revised version received 12
May 2002, and accepted 14 May 2002. Discussion open until 1 February 2003.

REFERENCE: Palmeira, E.M., Lima, Jr., N.R., and Mello, L.G.R., 2002, “Interaction
Between Soils and Geosynthetic Layers in Large-Scale Ramp Tests”, Geosynthetics
International, Vol. 9, No. 2, pp. 149-187.

Technical Paper by R.W.I. Brachman and R.P. Krushelnitzky

STRESS CONCENTRATIONS AROUND CIRCULAR HOLES IN PERFORATED DRAINAGE PIPES

ABSTRACT: Stress concentrations around circular holes in perforated buried pipes
obtained from three-dimensional elastic finite element analysis are presented. The maximum
stresses around the perforation were found to depend on the thickness and diameter
of the pipe, the diameter of the perforation, the circumferential location of the
perforation, and the axial and circumferential spacing between perforations. It was found
that a stress concentration of 3.0, based on the simple hole in a plate solution, may be
conservatively used for most perforated pipes. Better estimates of stress concentration
factors derived from finite element analysis are presented. Guidelines are provided for
specifying the location, size, and spacing of perforations that minimize the stress concentrations.
Two example calculations are presented to illustrate the proposed procedure
for estimating the maximum stresses around the perforations.

KEYWORDS: Pipe, Perforation, Stress concentration, Leachate collection, Landfill,
Heap-leach pad.

AUTHORS: R.W.I. Brachman, Assistant Professor, GeoEngineering Centre at
Queen’s-RMC, Department of Civil Engineering, Queen’s University, Kingston,
Ontario, Canada, K7L 3N6, Telephone: 1/613-533-3096, Telefax: 1/613-533-2128, Email:
brachman@civil.queensu.ca; and R.P. Krushelnitzky, Graduate Student, GeoEngineering
Centre at Queen’s-RMC, Department of Civil Engineering, Queen’s University,
Kingston, Ontario, Canada, K7L 3N6.

DATE: Original manuscript submitted 11 October 2001, revised version received 18
April 2002, and accepted 12 June 2002. Discussion open until 1 February 2003.

REFERENCE: Brachman, R.W.I. and Krushelnitzky, R.P., 2002, “Stress Concentrations
Around Circular Holes in Perforated Drainage Pipes”, Geosynthetics International,
Vol. 9, No. 2, pp. 189-213.