Geosynthetics International: Vol. 5, No. 3, 1998

To gain access the full text of the papers below, you must become a member of the IGS - if you are already an IGS Member, please to the Geosynthetics International Journal Archives in the Members Only section of the site.

Editorial by J.P. Giroud

THE NEW FEATURES IN GEOSYNTHETICS INTERNATIONAL  

As readers of Geosynthetics International must have noticed, there were three new features in the last issue of the Journal. Since it was a special issue, its editorial was naturally dedicated to a presentation of the technical content of the issue. Therefore, and befittingly, the new features of the Journal are introduced in the present editorial.

The most visible of these features is the new color of the cover. Although the blue cover used for Volumes 1 to 4 was distinctive, there was inconsistency in color from one issue to another and the lettering was occasionally less than sharp. The new white cover, introduced with Volume 5, is more distinctive and of an improved quality to reflect the high quality of the Journal contents.

Upon opening the Journal, on the inside of the front cover, the reader discovers the second of these features: the new composition of the Editorial Board. This is consistent with the Journal rules: the Editorial Board is appointed for four-year periods between international conferences on geosynthetics. Members of the Editorial Board are highly qualified experts who give freely of their time. To distribute the workload while maintaining continuity in standards, the Editorial Board is partially renewed every four years. I welcome old and new Board Members alike. Dr. Ingold, Dr. Bathurst, and I are currently working with them to deal with the substantial number of papers recently received.

Last, but not least, turning one more page of the Journal, the third new feature appears: an impressive list of Corporate Sponsors. In order to maintain the subscription rate at an acceptable level, companies active in the field of geosynthetics have been invited to become Corporate Sponsors of Geosynthetics International. The response has been tremendous and, to date, 51 companies have answered the call for corporate sponsorship. Dr. Ingold, Dr. Bathurst, and I express our deep gratitude to them, and we hope that other companies will follow their example. Also, we are encouraged because the enthusiastic response by companies from so many countries indicates that the high quality of the Journal has become widely recognized.

In conclusion, Geosynthetics International is a dynamic journal incorporating new ideas or changes when appropriate. With the experience gained by Editorial Board Members serving a second term, with the fresh air brought by new Editorial Board Members, and with the support provided by the Corporate Sponsors, Geosynthetics International is well equipped for the challenges of the next millennium.

INTERPRETATION OF TRANSMISSIVITY TEST DATA FOR GEONETS

ABSTRACT: Transmissivity tests were performed on a geonet confined between a pair of geomembranes under five increments of compressive stress ranging from 25 to 400 kPa. Each successive increment of stress was applied for 24 hours. In total, four geonets and seven geomembranes were evaluated in the test program. Measurements of flow rate per unit width through the geonet taken at five hydraulic gradients between the values of 0.02 and 0.10 indicate that the flow regime is semi-turbulent. Interpretation of the data addresses a comparison of flow behaviour in the geonet with that of fine gravel. A relative permeability factor is used to quantify the flow capacity in the semi-turbulent regime. The relationship between the relative permeability factor and the hydraulic gradient offers a useful approach for the estimation of flow capacity at gradients for which test data are not available. In contrast to the behaviour of gravels, a stress dependency of the curves may be expected at magnitudes of confining stress that result in a compression of the geonet and/or intrusion of the geomembrane into the apertures of the geonet.

KEYWORDS: Geonet, Drainage, Transmissivity, Relative permeability, Compressive stress, Hydraulic gradient.

AUTHORS: R.J. Fannin, Associate Professor, Department of Civil Engineering, and Forest Resources Management, University of British Columbia, 2324 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada, Telephone: 1/604-822-3557, Telefax: 1/604-822-6901, E-mail: fannin@civil.ubc.ca; H.W. Choy, Graduate Research Assistant, Department of Civil Engineering, University of British Columbia, 2324 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada; and J.W. Atwater, Associate Professor, Department of Civil Engineering, University of British Columbia, 2324 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada, Telephone: 1/604-822-4694, Telefax: 1/604-822-6901, E-mail: jatwater@civil.ubc.ca.

DATES: Original manuscript received 19 August 1997, revised version received 28 November 1997 and accepted 6 December 1997. Discussion open until 1 January 1999.

REFERENCE: Fannin, R.J., Choy H.W. and Atwater, J.W., 1998, "Interpretation of Transmissivity Test Data for Geonets", Geosynthetics International, Vol. 5, No. 3, pp. 265-285.

PERFORMANCE OF PROTECTIVE COVER SYSTEMS FOR LANDFILL GEOMEMBRANE LINERS UNDER LONG-TERM MSW LOADING

ABSTRACT: This paper presents the results of large-scale laboratory simulation tests conducted to evaluate the relative performance of different cover systems, consisting of a granular soil layer (i.e. a drainage layer) both with and without the presence of a needle-punched nonwoven geotextile, to protect a 1.5 mm thick smooth HDPE geomembrane liner under long-term municipal solid waste (MSW) loading conditions. Five different granular soils that range from a coarse gravel to a medium sand were used in the testing program. The protective cover system and the geomembrane liner were subjected to incremental loading to a maximum pressure of 1.4 MPa. The effect of long-term loading on the characteristics of the cover soils was assessed by performing particle size analyses, and the physical damage that occurred to the geomembrane liner was visually assessed in addition to performing multi-axial tension, wide strip tension, and water vapor transmission tests. The test results revealed that the degree of geomembrane liner protection decreases as the soil mean particle size increases and as the soil particle sphericity decreases. This study demonstrates that a 300 mm thick granular soil layer consisting of particles with a mean size less than 30 mm and a sphericity greater than 0.8, combined with a 270 g/m² nonwoven geotextile provides adequate protection for a 1.5 mm thick HDPE geomembrane liner from MSW loading.

KEYWORDS: Protective cover, Drainage layer, Liner systems, Geomembrane, Laboratory simulation, Long-term loading, Landfill.

AUTHORS: K.R. Reddy, Assistant Professor, and R.E. Saichek, Graduate Research Assistant, Department of Civil and Materials Engineering, University of Illinois at Chicago, 2095 Engineering Research Facility, 842 West Taylor Street, Chicago, Illinois 60607, USA, Telephone: 1/312-996-4755, Telefax: 1/312-996-2426, E-mail: kreddy@uic.edu.

DATES: Original manuscript received 29 October 1997, revised version received 27 February 1998 and accepted 7 March 1998. Discussion open until 1 January 1999.

REFERENCE: Reddy, K.R. and Saichek, R.E., 1998, "Performance of Protective Cover Systems for Landfill Geomembrane Liners Under Long-Term MSW Loading", Geosynthetics International, Vol. 5, No. 3, pp. 287-307.
 

THE CLOGGING OF NONWOVEN GEOTEXTILES WITH CATTLE MANURE SLURRIES

ABSTRACT: Three different types of heat-bonded, needle-punched, nonwoven polyester geotextile specimens with similar hydraulic conductivities, but with different O₉₀ values and average pore opening sizes, were exposed to a 3.6 m head of cattle manure slurry containing 7.5% total solids (TS) in laboratory columns to test the effect of pore opening size on geotextile specimen clogging. Geotextile specimens, with the smallest pore openings, were also exposed to 1, 2, and 4% TS cattle manure slurries to test the sealing effect of the TS. After 100 days of exposure to the slurries, geotextile specimen clogging was verified by measuring the geotextile specimen hydraulic conductivity using 0.9 and 3.65 m falling water head tests after removing all of the manure liquids and solids. The lowest volumetric infiltration rate, 1.1 L/m²/day, was obtained for geotextile specimens with the smallest pore opening size after 80 days of exposure to the 7.5% TS cattle manure slurry. Geotextile specimen infiltration rates were exponentially related to the amount of TS in the manure slurries. The geotextile specimen hydraulic conductivity values (for water), after the removal of the cattle manure slurries and all surface solids, was 105 times smaller that that measured before testing. This indicates that geotextile specimen clogging did occur while in contact with the cattle manure slurries.

KEYWORDS: Needle-Punched, Nonwoven, Polyester, Geotextile, Manure slurry, Clogging.

AUTHORS: S.F. Barrington, K. El Moueddeb and J. Jazestani, Department of Agricultural and Biosystems Engineering, Macdonald Campus of McGill University, 21 111 Lakeshore, Ste Anne de Bellevue, Québec, Canada, H9X 3V9, Telephone: 1/514-398-7776, Telefax: 1/514-398-8387, E-mail: barrington@agreng.lan.mcgill.ca; and M. Dussault, Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec, 4260 Rock Forest, Québec, Canada, J1N 2A5, Telephone: 1/819-820-3009, Telefax: 1/819-820-3942.

DATES: Original manuscript received 10 July 1997, revised version received 19 January 1998 and accepted 21 February 1998. Discussion open until 1 January 1999.

REFERENCE: Barrington, S.F., El Moueddeb, K., Jazestani, J. and Dussault, M., 1998, "The Clogging of Nonwoven Geotextiles With Cattle Manure Slurries", Geosynthetics International, Vol. 5, No. 3, pp. 309-325.

MODELLING OF GEOSYNTHETIC REINFORCEMENT IN SOIL RETAINING WALLS

ABSTRACT: The paper is focused on the behaviour of geosynthetic reinforcement layers in the active and anchorage zones of soil retaining walls. Differential equations that describe the reinforcement layer force/stress distribution, while embedded in soil, are derived for both elastic and visco-elastic reinforcement layers. The solutions to these differential equations provide a simple method of analysing the following phenomena: reinforcement pull-out, the influence of wall facing flexibility on the distribution of forces in the reinforcement, and stress relaxation in reinforcement layers that exhibit creep behaviour. Practical examples are used to illustrate the influence of parameter values on model predictions.

KEYWORDS: Reinforced soil, Geosynthetic, Metal, Pull-Out behaviour, Stress distribution, Creep, Rheological properties.

AUTHOR: A. Sawicki, Professor, Institute of Hydro-Engineering of the Polish Academy of Sciences, IBW PAN, ul. Koscierska 7, 80-953 Gdansk-Oliwa, Poland, Telephone: 48/58-552-20-11, or 48/58-552-39-03, Telefax: 48/58-552-42-11; E-mail: as@hapci.ibwpan.gda.pl.

DATES: Original manuscript received 4 August 1997, revised version received 19 December 1997 and accepted 21 February 1998. Discussion open until 1 January 1999.

REFERENCE: Sawicki, A., 1998, "Modelling of Geosynthetic Reinforcement in Soil Retaining Walls", Geosynthetics International, Vol. 5, No. 3, pp. 327-345.
 

A METHODOLOGY FOR THE EVALUATION OF GEOTEXTILE PORE OPENING SIZES UNDER CONFINING PRESSURE

ABSTRACT: This paper presents a methodology used to evaluate the pore opening sizes of a needle-punched, nonwoven polyester geotextile under pressure, using a permeameter subject to vibration. Particles passing through the geotextiles were collected and analysed to establish a particle size distribution curve. Preliminary results obtained under no confining pressure compare well with a standard test method based on hydrodynamic sieving. Confining pressures up to 25 kPa appeared to exert some influence on the pore opening size of relatively thin geotextiles. However, for pressures greater than 25 kPa, the variation of geotextile pore opening size is small. The tests results and microscopic observations suggest that needle-punching during the geotextile manufacturing process has a significant influence on the geotextile pore structure. Regardless of the limited amount of data available, the methodology described may provide a useful tool for the study of geotextile pore opening sizes under confining pressure.

KEYWORDS: Geotextile, Pore opening size, Filtration, Drainage, Confining pressure.

AUTHORS: E.M. Palmeira, Associate Professor of Civil Engineering, University of Brasilia, Dept. Civil Engineering, FT, 70910-900 Brasilia, DF, Brazil, Telephone: 55/61-273-7313, Telefax: 55/61-273-4644 or 272-0732, E-mail: palmeira@guarany.cpd.unb.br; and R.J. Fannin, Associate Professor, Department of Civil Engineering and Forest Resources Management, University of British Columbia, 2324 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada, Telephone: 1/604-822-3557, Telefax: 1/604-822-6901, E-mail: fannin@civil.ubc.ca

DATES: Original manuscript received 1 July 1997, revised version received 18 November 1997 and accepted 18 December 1997. Discussion open until 1 January 1999.

REFERENCE: Palmeira, E.M. and Fannin, R.J., 1998, "A Methodology for the Evaluation of Geotextile Pore Opening Sizes Under Confining Pressure", Geosynthetics International, Vol. 5, No. 3, pp. 347-357.

GEOSYNTHETICS 1999 CONFERENCE AND TRADE SHOW

Where?
World Trade Center, Boston, Massachusetts, USA

When?
28 to 30 April 1999

Who Will Attend this Biennial Conference and Trade Show?
Geosynthetic professionals from around the world including, civil, environmental, and geotechnical engineers, specifiers, fabricators, installers, contractors, geosynthetic manufacturers, government officials, project designers, and civil engineering students and professors.

Why?
The mandate of Geosynthetics 1999 is to showcase leading-edge innovations and trends in design, manufacturing, and construction in the geosynthetics industry, while bringing together more than 2,000 geosynthetics professionals and over 125 exhibitors to discuss practical and theoretical issues pertaining to geosynthetics.

New Conference Structure
Geosynthetics 1999 is restructuring its conference schedule to offer a new, practical track, in addition to the theoretical track, i.e. research, development, and industry questions, that existed in previous years. The practical track will focus on specifying geosynthetics and developing designs based on practical construction and actual field experience, rather than theoretical discussions.