The Influence of Tensile Stresses on the Filtration Characteristics of Geotextiles

Abstract

Laboratory tests to determine the permeability and retention characteristics of soil-geotextile systems are usually carried out with the geotextile in an unstressed state. A limited amount of work has been done on the effect of a compressive stress applied normal to the plane of the geotextile. However, there appears to be no information on the effect of in-plane tensile stresses, despite the fact that in many field applications geotextiles will be subjected to stresses of this nature. Geotextile permeability and retention results are presented in this paper for two different modes of tensile deformation of a geotextile: out-of-plane deformation associated with uniform multi-axial stresses; and in-plane deformation caused by the application of a uniaxial stress. The results illustrate the extreme importance of tensile stresses on the soil filtration characteristics of a geotextile. Out-of-plane deformations result in a greater loss of solid particles through the geotextile compared with unstressed geotextile specimens, whereas in-plane uniaxial deformations are associated with reductions in the permeability of the soil-geotextile system.

Filter Performance and Design for Highway Drains

“…This, in turn, influences the geotextile cross-flow hydraulic conductivity. The flow rate reduction, consecutive to axial loading, is much more severe with a woven geotextile, and also occurs at smaller tensile stress level, than with a nonwoven geotextile (Fourie and Kuchena, 1995). …”

“…If geotextiles are stretched by tensile forces along a planar direction, the FOS (see Chapter 2 for definition of FOS) is generally reduced by the opening elongation along the direction of force (Fourie and Kuchena, 1995). Besides the FOS reduction due to lateral load, another type of reduction in opening size can be expected from the vertical compression of the thickness due to the overburden pressure.…”

The influence of uniaxial tensile strain on the pore size and filtration characteristics of geotextiles

“…Permeability test results using nonwoven and woven geotextiles showed dramatic decreases in flow rate with relatively small increases in tensile stress. Tensile stresses of less than 3% of the ultimate tensile strength of the geotextile resulted in decreases in flow rate of up to 80% compared with the unstressed specimens (Fourie and Kuchena, 1995). Results from hydrodynamic sieving tests on two woven geotextiles showed that the opening size of the thicker geotextile decreased with increasing biaxial load, whereas the opposite occurred for the thinner of the two geotextiles (Fourie and Addis, 1999).…”

“…Limited works studying the effect of tensile strain on the filtration characteristics of geotextiles can be found in the literature (Fourie and Kuchena, 1995;Addis, 1997, 1999). Fourie and Addis (1997) conducted hydrodynamic sieving tests on a nonwoven and a woven geotextiles while in-plane tensile loads, biaxial and uniaxial, were applied.…”

Prediction of pore size characteristics of woven slit-film geotextiles subjected to tensile strains

“…The load-induced variations in the pore sizes affect the filtration behaviour of a woven slit-film geotextile. However, the characteristic pore sizes are commonly tested in the unstrained condition, which results in soil clogging or leaking despite the fact that the design criteria were satisfied (Fourie and Kuchena, 1995). Therefore, accurate determination of pore size parameters under certain tensile strains is important in the filtration design of woven slit-film geotextiles.…”