Geoscience Reference
In-Depth Information
Table 2
Partial Factors
Partial factors
Flexible
Stiff
Mechanical damage
1.05-1.7
1.1-1.7
Chemical attack
N/A-1.0
N/A-1.0
Hydrolysis
pH
,
9, T
,
50
8
:1.0
N/A
Thermo-oxidation
N/A
In special cases
Environmental attack
1.0
1.0
strength is not correct and therefore not applicable. BS 8006 does not require such a
factor either but uses a partial factor in the calculation of the anchor length instead.
FHWA (1997) follows the same design approach.
9 SUMMARY
The availability of data relating to stress-strain curves, long-term stress rupture
against time and stiffness, together with the basis for definition of junction
strength are summarized in
Table 1
for flexible and stiff geogrids. Data
determined by direct testing are classified as available and data derived from
graphical construction are classified as Sherby-Dorn plots.
Typical values for partial factors for mechanical damage, chemical attack,
hydrolysis,
thermo-oxidation, and environmental attack are summarized in
Table 2.
10 CONCLUSIONS
With the present BS 8006, FHWA, and independent certification of product
characteristics as carried out by BBA, a sound base for the use of geogrids
products is now available. The many geogrid products offer a range of products
from which specifiers and contractors can select the product best suited to their
specific purpose. However, it should be emphasized that the proper design
parameters must be accurately specified to enable the selection of the correct
geogrid.
The design strength should be clearly specified for a design life while the
design conditions that influence the various partial factors should also be listed.
In fact, the designer should specify which partial factors he has used in his design.
When a product is proposed to be used with different characteristics, it is then
possible to analyze the differences between the products with regards to
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