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Chapter 10 — References & Appendices

References

The manual's reference list spans the reinforced-soil literature: Vidal's original reinforced-earth work; the FHWA Reinforced Soil Structures volumes; the AASHTO Bridge Design Specifications; geosynthetic design guidelines; and the research literature on pullout, creep, durability, and connection strength. It is the starting point for any parameter that must be justified beyond the manual's own tables.

Appendix A — Determination of pullout resistance factors

A.1 Empirical procedures to determine \(F^{*}\) and \(\alpha\). For routine design, the pullout friction factor \(F^{*}\) and the scale correction factor \(\alpha\) are obtained from the soil's friction angle and the reinforcement type, using the manual's empirical charts. This is the default route when pullout tests are not warranted.

A.2 Experimental procedures to determine \(F^{*}\) and \(\alpha\). Where the soil–reinforcement combination is unusual, or where the empirical values are not conservative, pullout tests are performed: the reinforcement is embedded in the candidate fill and pulled out under a known normal stress, and \(F^{*}\) (and, for extensible reinforcement, \(\alpha\)) is back-calculated from the measured resistance. The appendix gives the test setup, the interpretation, and the normalization.

A.3 Connection resistance and strength. The connection between reinforcement and facing may be the weakest link in the system. The appendix describes connection tests for partial- and full-friction segmental block/reinforcement connections, and how to derive the design connection strength from the load–displacement and rupture data.

Appendix B — Determination of the creep strength reduction factor

B.1 Background. Geosynthetic reinforcement creeps — it strains continuously under sustained load — so its long-term strength is lower than its short-term strength. The creep reduction factor \(RF_{CR}\) quantifies the loss.

B.2 Step-by-step procedures for extrapolating stress-rupture data. Because a structure must perform for decades, the long-term strength cannot be measured directly. The appendix gives the standard procedure: run stress-rupture tests at elevated temperatures, use time–temperature superposition (shift factors) to construct a master curve, and extrapolate it to the design life to find the creep limit load.

B.3 Use of creep data from "similar" products. Where product-specific data are unavailable, data from similar polymers and structures may be used with justification.

B.4 Creep extrapolation examples. Two fully worked extrapolations — one for a PET (polyester) geosynthetic and one for a polyolefin (polypropylene/ polyethylene) geosynthetic — take raw stress-rupture data through shifting and extrapolation to a creep limit load, and thence to \(RF_{CR}\).

Appendix C — Approximate cost range of geotextiles and geogrids

Dated cost ranges for geosynthetic reinforcement, for order-of-magnitude estimating. Re-base to current local prices before use.

Appendix D — Typical dimensions of steel reinforcements

Standard cross-sections, dimensions, and areas of the steel strips, bar mats, and wire grids used in metallic-reinforced systems — the tabulated data behind the corrosion-allowance calculation in Chapter 3.

Appendix E — Example reinforced soil slope analysis with the RSS computer program

A complete worked reinforced-slope analysis using the FHWA RSS program: input geometry and soil properties, the reinforcement layout, the critical-surface search, and the resulting factor of safety — the computer counterpart to the hand examples in Chapter 7.

Key takeaways

  • Pullout factors come from charts by default, from tests when the combination is unusual — Appendix A.
  • Creep strength must be extrapolated from accelerated tests, not assumed — Appendix B.
  • Connection strength can govern; test it — Appendix A.3.
  • Cost data (Appendix C) and standard dimensions (Appendix D) are dated reference data — re-base and re-verify before use.
  • Appendix E is the worked computer analysis that closes the design loop.