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Geosynthetics International: Vol.8, No. 3, 2001
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Technical Paper by S.A. Aiban and S.M. Ali
NONWOVEN GEOTEXTILE-SABKHA
AND -SAND INTERFACE FRICTION
CHARACTERISTICS USING PULL-OUT TESTS
ABSTRACT: Sabkha soil is abundant along the Arabian Gulf and
Red Sea coasts and is a problematic soil due to its acute water sensitivity and
chemical aggressiveness. In many situations, it is required to improve the load
carrying capacity of sabkha, and the use of geotextiles was found appropriate.
The objectives of this research were to study frictional characteristics of
sand-geotextile-sand and sabkha-geotextile-sand interfaces and to compare the
pull-out resistance of locally available nonwoven geotextiles taking into
account different test parameters. An experimental setup was developed to
KEYWORDS: Sabkha, Sand, Geotextile, Pull-out, Residual
state, Slippage, Soaking.
AUTHORS: S.A. Aiban, Associate Professor
and S.M. Ali, Research Assistant, Department of Civil Engineering, King Fahd
University of Petroleum
and Minerals
DATE: Original manuscript submitted 18 July 2000, revised
version received 9 April 2001, and accepted 12 April 2001. Discussion open
until 1 January 2002.
REFERENCE: Aiban,
S.A. and Ali, S.M., 2001, “Nonwoven
Geotextile-Sabkha and -Sand Interface Friction Characteristics Using Pullout
Tests”, Geosynthetics International, Vol. 8, No. 3, pp. 193-220.
Technical Paper by N. Hytiris, D.J. McKay, and P.S. Addison
A CANOPY FLOW EQUATION FOR EROSION CONTROL GEOSYNTHETICS
ABSTRACT: A novel experimental test programme for erosion
control geosynthetic mattings, i.e., geomats, is described. Using a laser
Doppler anemometer, the velocities have been examined within the flow field at
the fluid-geomat interface. Initial analysis of the test results has lead to
a modified log-law equation for the downstream flow velocities above the geomat.
This equation has the same form as canopy flow equations used in meteorology
to
describe the velocity profiles above vegetative canopies in the atmospheric boundary
layer. The canopy flow equation for erosion control geotextiles is discussed
herein.
KEYWORDS: Erosion control, Geomat, Laser Doppler
anemometery, Hydraulic, Velocity distribution profile, Log-law, Canopy flow,
Roughness coefficient.
AUTHORS: N. Hytiris, Senior Lecturer, Department of Energy
and Environmental Technology, Glasgow Caledonian University, Glasgow, Scotland,
United Kingdom, Telephone: 44/141-331-3686, Telefax: 44/141-331-3370, E-mail:
N. Hytiris@ gcal.ac.uk; D.J. McKay, Doctoral candidate, Department of Energy
and Environmental Technology, Glasgow Caledonian University, Glasgow, Scotland,
United Kingdom, Telephone: 44/141-331-3590, E-mail: djsmckay@hotmail.com; and
P.S. Addison, Senior Lecturer, School of the Built Environment, Napier
University, Edinburgh, Scotland, United Kingdom, Telephone: 44/131-455-2302,
Telefax: 44/131-455-2239, E-mail: P.Addison@napier.ac.uk.
DATE: Original manuscript submitted 18 July
2000, revised version received 9 April 2001, and accepted 12 April 2001. Discussion
open
until 1 January 2002.
REFERENCE: N. Hytiris, D.J. McKay, and P.S. Addison, 2001, “A Canopy Flow Equation For Erosion Control Geosynthetics”, Geosynthetics International, Vol. 8, No.3, pp. 221-232.
Technical Paper by A.L. Li and R.K. Rowe
INFLUENCE OF CREEP AND STRESS-RELAXATION OF GEOSYNTHETIC
REINFORCEMENT ON EMBANKMENT BEHAVIOUR
ABSTRACT: The effects of viscous behaviour of geosynthetic
reinforcement on both the short-term and long-term performance of basally
reinforced embankments over inviscous soft foundations are investigated. The
construction of embankments reinforced with both viscous reinforcement and
inviscous reinforcement is numerically simulated to identify the magnitude of
creep and stress-relaxation of reinforcement under both limit-state and working
stress conditions and the consequent effects on the stability and deformations
of the system. The effects of viscoelastic properties of four reinforcement
products made of polyester, polypropylene, and polyethylene are examined. It is
shown that the viscous behavior of geosynthetic reinforcement can decrease the
short-term stability, and the creep of geosynthetic reinforcement can
significantly magnify the long-term shear deformations of the foundation soil.
The isochronous stiffness can reasonably represent the mobilized reinforcement
stiffness at the end of construction. The mobilized reinforcement stiffness and
force are examined and the design considerations
are discussed.
KEYWORDS: Reinforced embankment, Geosynthetic reinforcement,
Creep, Viscoelasticity, Soft soil, Stability.
AUTHORS: A.L. Li, Postdoctoral Fellow,
Department of Civil Engineering, Queen’s University, Kingston, Ontario, Canada K7K 3N6, Telephone:
1/613-533-6000, Ext. 77558, Telefax: 1/613-533-2128; E-mail:
li@civil.queensu.ca; and R.K. Rowe, Professor, Vice Principal (Research),
Queen’s University, Kingston, Ontario, Canada K7K 3N6, Telephone:
1/613-533-6933, Telefax: 1/613-533-6934, E-mail: kerry@civil.queensu.ca.
Corresponding author: R.K. Rowe.
DATE: Original manuscript submitted 20 March 2001, revised
version received 3 July 2001, and accepted 6 July 2001. Discussion open until 1
January 2002.
REFERENCE: Li, A.L. and Rowe, R.K.,
2001, “Influence of
Creep and Stress-Relaxation of Geosynthetic Reinforcement on Embankment
Behaviour”, Geosynthetics International, Vol. 8, No. 3, pp. 233-270.
MEASUREMENT OF GEOTEXTILE-WATER CHARACTERISTIC CURVES USING
A CONTROLLED OUTFLOW CAPILLARY PRESSURE CELL
ABSTRACT: The present paper describes the use of a
controlled outflow capillary pressure cell for the measurement of
geotextile-water characteristic curves. Fine sand with a known soil-water
characteristic curve and a geotextile column drainage experiment were used to
validate the controlled outflow cell. The controlled outflow cell was also used
to measure drainage geotextile-water characteristic curves for one, three, and six
vertically stacked nonwoven geotextile specimen layers. Test results indicate
the following: (i) the controlled outflow cell can measure a complete nonwoven
drainage geotextile-water characteristic curve with a water entry pressure of
50 mm; (ii) vertical stacking of the nonwoven geotextile has little influence
on the geotextile-water characteristic
KEYWORDS: Geotextile-water characteristic curve, Unsaturated
flow, Geotextile, Nonwoven.
AUTHORS: M.A. Knight, Assistant Professor, and S.M. Kotha,
Masters candidate, Department of Civil Engineering, University of Waterloo,
Waterloo, Ontario, Canada, N2L 3G1, Telephone: 1/519-885-1211, Ext. 6919,
Telefax: 1/519-888-6197, E-mail: maknight@uwaterloo.ca and
smkotha@engmail.uwaterloo.ca, respectively.
DATE: Original manuscript submitted 17 February 2000,
revised version received 10 January 2001, and accepted 29 January 2001.
Discussion open until 1 January 2002.
REFERENCE: Knight, M.A. and Kotha, S.M., 2001, “Measurement of Geotextile-Water Characteristic Curves Using a Controlled Outflow Capillary Pressure Cell”, Geosynthetics International, Vol. 8, No. 3, pp. 271-282.