Geoscience Reference
In-Depth Information
(E.1)
Tpr
p
⋅
where:
T
=
tensile load in the geotextile [kN/m];
p
=
pressure in the fill material [kPa];
r
=
radius of curvature at a random point on the circumference of the geotextile
tube [m].
The resulting formulae have analytical solutions but due to their complexity these
can only be solved using numerical methods. Without using Table D.1 the calculation
does not lend itself to a 'quick calculation by hand'.
The results, according to Timoshenko, can be shown graphically (see Figures 5.7
to 5.9). Figure E.2 shows one set of calculations using a 12 m circumference tube.
In practice, the hydrostatic pressure on the upper tube side lies within much nar-
rower margins than shown in Figure E.2, normally between the 0.5 and 1 m water
113 kN/m, 5 m, 96%
3.4
3.2
62 kN/m, 5 m, 93%
3.0
31 kN/m, 1 m, 87%
2.8
2.6
19 kN/m, 0.5 m, 81%
2.4
2.2
2.0
1.8
7.5 kN/m, 0.1 m, 60%
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
half-width
Figure E.2
Results of numerical calculations. Shape of a geotextile tube with a circumference of 12 m
for various degree of filling values (based on volume). The numbers for each line shows
respectively the tensile load in the geotextile, the pressure head in metres of water on the
upper side of the tube and the degree of filling (expressed as a percentage). Calculations
have been performed for a fill material that has a 10 kPa higher pressure than the external
surroundings (e.g., filling with a sand-water mixture under water). Clearly the tensile load
in the geotextile increases significantly at a higher degree of filling.
