Influence of fibers on the shear strength and dewatering performance of geotextile tubes

M. M. Khachan, Shobha K Bhatia

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Geotextile tubes have been widely used for the dewatering of high water content fine sediments. Fine sediments include lake sediments, organic soils and coal combustion products, which generally have low shear strength. Several researchers have emphasized the effect of the retained sediment (filter cake) properties on dewatering performance and stability of the geotextile tubes. Maintaining retained sediment properties, in particular permeability and shear strength, allows for faster dewatering time, better retention of sediments and improved stability of the geotextile tubes during multiple filling stages and during the tube stacking process. Several studies have shown that the use of synthetic fibers can increase the shear strength of sand, silt and clays. However, the use of fibers to improve the strength of retained sediments in geotextile tubes has not been explored. In this study, three synthetic fibers varying in length and diameter were used to evaluate the effect of fibers on the dewatering performance and shear strength of the fine sediments. A cationic polyacrylamide flocculant was used as an optimum conditioner for the selected sediment. The fibers were mixed with the flocculant conditioned slurry at 0.25, 0.5, 1 and 2% fiber concentration by mass of the dry solids. The effect of fibers on the undrained shear strength of the dewatered sediments was evaluated using a lab vane test, fall cone test and undrained unconsolidated triaxial test. Jar tests and pressure filtration tests were also conducted to evaluate the effect of fiber on the required flocculant dosage and on the dewatering performance. Based on the results of this study, 0.5% of F1 fiber type was found to be the optimum fiber concentration, yielding an approximately 100% increase in undrained shear strength. It was also found that the diameter and length of the fibers play a significant role in altering the undrained shear strength of the tested sediments. The relatively short (6 mm) and thick (38 μm) fiber did not yield an increase in shear strength for all the tested fiber concentrations, whereas thin fibers (9 μm) of similar length increased the shear strength by 100%. Furthermore, it was found that the use of fibers at any concentration decreases the required optimum doses of flocculant by about 15%, and increases the dewatering rate of the effluents by about 50%.

Original languageEnglish (US)
Pages (from-to)317-330
Number of pages14
JournalGeosynthetics International
Volume23
Issue number5
DOIs
StatePublished - Oct 1 2016

Fingerprint

Geotextiles
geotextile
Dewatering
dewatering
Shear strength
shear strength
Sediments
Fibers
sediment
Synthetic fibers
fibre
Soil conditioners
Coal combustion
Silt
sediment property
Polyacrylates
Water content
triaxial test
Lakes
Cones

Keywords

  • Dewatering
  • Geosynthetics
  • Geotextile tube
  • Shear strength
  • Synthetic fibers

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

Cite this

Influence of fibers on the shear strength and dewatering performance of geotextile tubes. / Khachan, M. M.; Bhatia, Shobha K.

In: Geosynthetics International, Vol. 23, No. 5, 01.10.2016, p. 317-330.

Research output: Contribution to journalArticle

@article{e53e84220efb426987052ad95c5dfcdc,
title = "Influence of fibers on the shear strength and dewatering performance of geotextile tubes",
abstract = "Geotextile tubes have been widely used for the dewatering of high water content fine sediments. Fine sediments include lake sediments, organic soils and coal combustion products, which generally have low shear strength. Several researchers have emphasized the effect of the retained sediment (filter cake) properties on dewatering performance and stability of the geotextile tubes. Maintaining retained sediment properties, in particular permeability and shear strength, allows for faster dewatering time, better retention of sediments and improved stability of the geotextile tubes during multiple filling stages and during the tube stacking process. Several studies have shown that the use of synthetic fibers can increase the shear strength of sand, silt and clays. However, the use of fibers to improve the strength of retained sediments in geotextile tubes has not been explored. In this study, three synthetic fibers varying in length and diameter were used to evaluate the effect of fibers on the dewatering performance and shear strength of the fine sediments. A cationic polyacrylamide flocculant was used as an optimum conditioner for the selected sediment. The fibers were mixed with the flocculant conditioned slurry at 0.25, 0.5, 1 and 2{\%} fiber concentration by mass of the dry solids. The effect of fibers on the undrained shear strength of the dewatered sediments was evaluated using a lab vane test, fall cone test and undrained unconsolidated triaxial test. Jar tests and pressure filtration tests were also conducted to evaluate the effect of fiber on the required flocculant dosage and on the dewatering performance. Based on the results of this study, 0.5{\%} of F1 fiber type was found to be the optimum fiber concentration, yielding an approximately 100{\%} increase in undrained shear strength. It was also found that the diameter and length of the fibers play a significant role in altering the undrained shear strength of the tested sediments. The relatively short (6 mm) and thick (38 μm) fiber did not yield an increase in shear strength for all the tested fiber concentrations, whereas thin fibers (9 μm) of similar length increased the shear strength by 100{\%}. Furthermore, it was found that the use of fibers at any concentration decreases the required optimum doses of flocculant by about 15{\%}, and increases the dewatering rate of the effluents by about 50{\%}.",
keywords = "Dewatering, Geosynthetics, Geotextile tube, Shear strength, Synthetic fibers",
author = "Khachan, {M. M.} and Bhatia, {Shobha K}",
year = "2016",
month = "10",
day = "1",
doi = "10.1680/jgein.15.00053",
language = "English (US)",
volume = "23",
pages = "317--330",
journal = "Geosynthetics International",
issn = "1072-6349",
publisher = "ICE Publishing Ltd.",
number = "5",

}

TY - JOUR

T1 - Influence of fibers on the shear strength and dewatering performance of geotextile tubes

AU - Khachan, M. M.

AU - Bhatia, Shobha K

PY - 2016/10/1

Y1 - 2016/10/1

N2 - Geotextile tubes have been widely used for the dewatering of high water content fine sediments. Fine sediments include lake sediments, organic soils and coal combustion products, which generally have low shear strength. Several researchers have emphasized the effect of the retained sediment (filter cake) properties on dewatering performance and stability of the geotextile tubes. Maintaining retained sediment properties, in particular permeability and shear strength, allows for faster dewatering time, better retention of sediments and improved stability of the geotextile tubes during multiple filling stages and during the tube stacking process. Several studies have shown that the use of synthetic fibers can increase the shear strength of sand, silt and clays. However, the use of fibers to improve the strength of retained sediments in geotextile tubes has not been explored. In this study, three synthetic fibers varying in length and diameter were used to evaluate the effect of fibers on the dewatering performance and shear strength of the fine sediments. A cationic polyacrylamide flocculant was used as an optimum conditioner for the selected sediment. The fibers were mixed with the flocculant conditioned slurry at 0.25, 0.5, 1 and 2% fiber concentration by mass of the dry solids. The effect of fibers on the undrained shear strength of the dewatered sediments was evaluated using a lab vane test, fall cone test and undrained unconsolidated triaxial test. Jar tests and pressure filtration tests were also conducted to evaluate the effect of fiber on the required flocculant dosage and on the dewatering performance. Based on the results of this study, 0.5% of F1 fiber type was found to be the optimum fiber concentration, yielding an approximately 100% increase in undrained shear strength. It was also found that the diameter and length of the fibers play a significant role in altering the undrained shear strength of the tested sediments. The relatively short (6 mm) and thick (38 μm) fiber did not yield an increase in shear strength for all the tested fiber concentrations, whereas thin fibers (9 μm) of similar length increased the shear strength by 100%. Furthermore, it was found that the use of fibers at any concentration decreases the required optimum doses of flocculant by about 15%, and increases the dewatering rate of the effluents by about 50%.

AB - Geotextile tubes have been widely used for the dewatering of high water content fine sediments. Fine sediments include lake sediments, organic soils and coal combustion products, which generally have low shear strength. Several researchers have emphasized the effect of the retained sediment (filter cake) properties on dewatering performance and stability of the geotextile tubes. Maintaining retained sediment properties, in particular permeability and shear strength, allows for faster dewatering time, better retention of sediments and improved stability of the geotextile tubes during multiple filling stages and during the tube stacking process. Several studies have shown that the use of synthetic fibers can increase the shear strength of sand, silt and clays. However, the use of fibers to improve the strength of retained sediments in geotextile tubes has not been explored. In this study, three synthetic fibers varying in length and diameter were used to evaluate the effect of fibers on the dewatering performance and shear strength of the fine sediments. A cationic polyacrylamide flocculant was used as an optimum conditioner for the selected sediment. The fibers were mixed with the flocculant conditioned slurry at 0.25, 0.5, 1 and 2% fiber concentration by mass of the dry solids. The effect of fibers on the undrained shear strength of the dewatered sediments was evaluated using a lab vane test, fall cone test and undrained unconsolidated triaxial test. Jar tests and pressure filtration tests were also conducted to evaluate the effect of fiber on the required flocculant dosage and on the dewatering performance. Based on the results of this study, 0.5% of F1 fiber type was found to be the optimum fiber concentration, yielding an approximately 100% increase in undrained shear strength. It was also found that the diameter and length of the fibers play a significant role in altering the undrained shear strength of the tested sediments. The relatively short (6 mm) and thick (38 μm) fiber did not yield an increase in shear strength for all the tested fiber concentrations, whereas thin fibers (9 μm) of similar length increased the shear strength by 100%. Furthermore, it was found that the use of fibers at any concentration decreases the required optimum doses of flocculant by about 15%, and increases the dewatering rate of the effluents by about 50%.

KW - Dewatering

KW - Geosynthetics

KW - Geotextile tube

KW - Shear strength

KW - Synthetic fibers

UR - http://www.scopus.com/inward/record.url?scp=84988649507&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84988649507&partnerID=8YFLogxK

U2 - 10.1680/jgein.15.00053

DO - 10.1680/jgein.15.00053

M3 - Article

VL - 23

SP - 317

EP - 330

JO - Geosynthetics International

JF - Geosynthetics International

SN - 1072-6349

IS - 5

ER -