Geoscience Reference
In-Depth Information
Profix
®
tube mattress
BeauMatt
®
Figure 4.2
Profix
®
tube mattress and the BeauMatt
®
mattress.
The tube mattress.
This is the most common type of mattress. The geotextile
layers are sewn together lengthwise so that parallel tubes are formed that can be
filled with sand. Since the 'flat' tubes are inflated when filled, the tube shrinks
cross-wise by approximately 20-25%. Depending on the distance between seams,
different diameter tubes can be formed.
The shallow spherical mattress.
This mattress undergoes the same produc-
tion process as the tube mattress but less geotextile is used for the lower
mattress enabling the tubes to become a semi-cylindrical shape after fill-
ing, and where the mattress does not contract during filling. The mattresses
can be placed such that the tubes lie in the direction down the slope or hori-
zontal to it.
For the stability calculations, a distinction must be made between the thickness
of the tubes in the geotextile mattress and the average thickness of the geotextile mat-
tress itself. In general:
D
D
k
d
=
.6 to 0.8
(90% to 95% filled)
(4.1)
06
where:
D
k
=
effective thickness of the geotextile mattress [m];
D
d
=
maximum diameter of the mattress tubes [m].
A frequently used (average) mattress thickness is 0.20 m.
It should be noted that many similarities exist between the design process for
geotextile mattresses and that for geotextile bags. This does not mean that there is no
difference between the designs using the two types of encapsulated sand elements. For
example, the potential failure mechanisms for the overall structure will differ consid-
erably and thus require different design approaches.
