PD ISO/TR 20432:2007

Foreword
1 Scope
2 Normative references
3 Terms, definitions, abbreviated terms and symbols
   3.1 Terms and definitions
   3.2 Abbreviated terms
   3.3 Symbols
4 Design procedure
   4.1 Introduction
   4.2 Design lifetime
   4.3 Causes of degradation
   4.4 Design temperature
5 Determination of long-term (creep) strain
   5.1 Introduction
   5.2 Extrapolation
   5.3 Time-temperature superposition methods
   5.4 Isochronous curves
   5.5 Weathering, chemical and biological effects
6 Determination of long-term strength
   6.1 Tensile strength
   6.2 Reduction factors
   6.3 Modes of degradation
7 Creep rupture
   7.1 Introduction
   7.2 Measurement of creep rupture: conventional method
   7.3 Curve fitting (conventional method)
   7.4 Curve fitting for time-temperature block shifting of
        rupture curves
   7.5 Strain shifting and the stepped isothermal method
   7.6 Extrapolation and definition of reduction factor or
        lifetime
   7.7 Residual strength
   7.8 Reporting of results
   7.9 Procedure in the absence of sufficient data
8 Installation damage
   8.1 General
   8.2 Data recommended
   8.3 Calculation of reduction factor
   8.4 Procedure in the absence of direct data
9 Weathering, chemical and biological degradation
   9.1 Introduction
   9.2 Data recommended for assessment
   9.3 Weathering
   9.4 Chemical degradation
   9.5 Biological degradation
10 Determination of long-term strength
   10.1 Factor of safety f[s]
   10.2 Design for residual strength
11 Reporting
Bibliography

Gives guidelines for the determination of the long-term strength of geosynthetics for soil reinforcement.

This Technical Report provides guidelines for the determination of the long-term strength of geosynthetics for soil reinforcement.

This Technical Report describes a method of deriving reduction factors for geosynthetic soil-reinforcement materials to account for creep and creep rupture, installation damage and weathering, and chemical and biological degradation. It is intended to provide a link between the test data and the codes for construction with reinforced soil.

The geosynthetics covered in this Technical Report include those whose primary purpose is reinforcement, such as geogrids, woven geotextiles and strips, where the reinforcing component is made from polyester (polyethylene terephthalate), polypropylene, high density polyethylene, polyvinyl alcohol, aramids and polyamides 6 and 6,6. This Technical Report does not cover the strength of joints or welds between geosynthetics, nor whether these might be more or less durable than the basic material. Nor does it apply to geomembranes, for example, in landfills. It does not cover the effects of dynamic loading. It does not consider any change in mechanical properties due to soil temperatures below 0°C, nor the effect of frozen soil. The Technical Report does not cover uncertainty in the design of the reinforced soil structure, nor the human or economic consequences of failure.

Any prediction is not a complete assurance of durability.