Geoscience Reference
In-Depth Information
tensile strength and a high maximum strain. The Young's modulus
E
or the tensile
stiffness
J
of the geotextile can be derived from its maximum allowable tensile load
(
T
m
) and corresponding strain.
T
(2.2)
E
=
t
ε
⋅
mg
t
T
(2.3)
⋅
JEt
T
E
=
g
ε
m
where:
t
g
=
thickness of the geotextile [m];
ε
m
=
maximum strain of the geotextile [
−
].
T
m
is defined as the maximum allowable tensile load in the geotextile, equal to the
maximum tensile strength of the geotextile.
It should be realised that, in reality, there is normally a non-linear relation between
the tensile load and the strain and hence the stiffness modulus derived in this way is
only an approximation of the real stiffness behaviour.
Table 2.4 lists indicative tensile strengths and corresponding maximum strains of
the most common woven geotextile types. For the calculation of
J
use is made of the
average value of
ε
m
.
2.4.5 Seams
The overall strength of these elements is in many cases governed by the strength of the
seams. The seam strength depends on the type of seam, the thread type and stitch den-
sity used, and can vary from 30% to more than 80% of the strength of the geotextile.
Table 2.5 shows the most commonly applied seams and the corresponding typical
strength efficiencies obtained. This table is derived from Table 8 in [8] and relates to
seams made in the factory. For seams made on-site, by a hand sewing machine, lower
strengths are normally obtained. For a stronger (heavier) geotextile this percentage
Table 2.4
Tensile strength and corresponding strain for various various geotextile types [22].
T
m
[kN/m]
ε
max
[%]
J
[kN/m]
T
m
*
ε
m
[kN/m]
Geotextile
Polyester (PET)
100-1600
8-15
870-16000
8-210
Polypropylene (PP)
40-300
10-15
320-2400
4-45
Polyethylene (PE)
20-50
20-30
80-200
4-15
Membrane
7-70
50-100
9-90
4-70
T
m
=
tensile strength of the geotextile [kN/m].
ε
m
=
strain at maximum allowable tensile strength of the geotextile [%].
J
=
tensile stiffness modulus of the geotextile [kN/m].
