BS 8006
BS 8006:1995 Section 7 — Reinforced Slopes
BS 8006:1995Revision 2Required FoS ≥ 1
Use it in Slope
In a design, choose it under Analyze → Design factor set, and the PDF report runs it too.
Checked against the standard · Not yet validated
Known limitations
- Table 26 gives ultimate values only; a helping dead load is taken at ×1.0 and a helping live load at ×0 (Slope convention, not the standard's).
- Pore pressure is scaled with ffs (Slope's water rule); 7.4.4.3 subtracts it unfactored.
- χ = 1.25 divides the soil's shear resistance in every method and inside Bishop's m_α; 7.4.4.3 defines it for circular slices only, with m_α undivided; the direct-sliding check takes it too.
- Layer rupture is divided by the fm entered on each element (7.2.3, Annex A); Annex A.2 gives fm = 1.50 for plain or galvanised steel in axial tension only.
- Consequence category 1 is not applicable (Table 3: structures designed by experience, without analysis); a reinforced run under it is refused.
- Direct sliding across a layer takes a′·tanφ′p/fms and a′bc·c′/fms ÷ fs (6.5.3 form); fn does not apply.
- Anchors, soil nails and piles are outside Section 7 and are unfactored; design soil nails to BS 8006-2.
- Other strength models (Hoek–Brown, hyperbolic) are unfactored.
Scope
- Soil nails: BS 8006:1995 gives no partial factors for soil nails (7.5) — design them to BS 8006-2.
Values
Actions
| Soil weightγ | Unfavorable | ×1.50 |
| Favorable | ×1.50 | |
| Permanent loadγG | Unfavorable | ×1.20 |
| Favorable | ×1.00 | |
| Variable loadγQ | Unfavorable | ×1.30 |
| Favorable | ×0.00 | |
| Seismic coefficientγE | ×1.00 | |
Resistance
| Earth / global resistanceγRe | ÷1.25 | |
Materials
| Effective cohesionγc′ | ÷1.60 | |
| Friction (tanφ′)γφ | ÷1.00 | |
| Undrained strength (cu)γcu | ÷1.00 | |
| Shear strength (other models)— | ÷1.00 | |
Reinforcement
| Geosynthetic — ruptureγt | ÷1.00 | |
| Geosynthetic — pull-outγpo | ÷1.30 | |
| Geosynthetic — sliding acrossfs | ÷1.30 | |
| Steel strip — ruptureγt | ÷1.00 | |
| Steel strip — pull-outγpo | ÷1.30 | |
| Steel strip — sliding acrossfs | ÷1.30 | |
| Steel grid — ruptureγt | ÷1.00 | |
| Steel grid — pull-outγpo | ÷1.30 | |
| Steel grid — sliding acrossfs | ÷1.30 | |
Sources
Document: BS 8006:1995
Actions
| Factor | Value | Source |
|---|---|---|
| Soil weight — unfavorable | ×1.50 | 7.4.4.3, Table 26, ffs, PDF p112 · Departure from the standard · Not yet validated — ffs multiplies the whole slice weight on both sides (7.4.4.3, single source), and Slope scales the pore pressure with it; 7.4.4.3 subtracts b·u unfactored. |
| Soil weight — favorable | ×1.50 | 7.4.4.3, Table 26, ffs, PDF p112 · Departure from the standard · Not yet validated — ffs multiplies the whole slice weight on both sides (7.4.4.3, single source), and Slope scales the pore pressure with it; 7.4.4.3 subtracts b·u unfactored. |
| Permanent load — unfavorable | ×1.20 | 7.2.2, Table 26, ff, PDF p109 · Not yet validated |
| Permanent load — favorable | ×1.00 | 7.2.2, Table 26, PDF p109 · Slope convention · Not yet validated — The table gives ultimate values only (its 1.0 is the serviceability column); a helping dead load is taken at ×1.0. |
| Variable load — unfavorable | ×1.30 | 7.2.2, Table 26, fq, PDF p109 · Not yet validated |
| Variable load — favorable | ×0.00 | 7.2.2, Table 26, PDF p109 · Slope convention · Not yet validated — Table 26 gives no favourable factor; a helping live load is omitted (cf. Table 17 combination B, fq = 0, which 7.2.2 applies to steep slopes). |
| Seismic coefficient | ×1.00 | 5.6.2.1, PDF p55 · Slope convention · Not yet validated — BS 8006:1995 gives no seismic partial factor. |
Materials
| Factor | Value | Source |
|---|---|---|
| Effective cohesion | ÷1.60 | 7.2.3, Table 26, fms on c′, PDF p109 · Not yet validated |
| Friction (tanφ′) | ÷1.00 | 7.2.3, Table 26, fms on tan φ′p, PDF p109 · Not yet validated |
| Undrained strength (cu) | ÷1.00 | 7.2.3, Table 26, PDF p109 · Slope convention · Not yet validated — Table 26 has no cu row; walls Table 16 and embankments Table 27 give fms = 1.0. |
| Shear strength (other models) | ÷1.00 | 7.2.3, Table 26, PDF p109 · Slope convention · Not yet validated — BS 8006 gives no factor for other strength models; they are unfactored. |
Resistance
| Factor | Value | Source |
|---|---|---|
| Earth / global resistance | ÷1.25 | 7.4.4.3, PDF p112 · Slope convention · Not yet validated — χ divides the soil's shear resistance only, never the reinforcement. Slope applies it in every method and also inside Bishop's m_α; 7.4.4.3 defines it for circular slices and leaves tan φ′p/fms in m_α undivided. |
Reinforcement
| Factor | Value | Source |
|---|---|---|
| Geosynthetic — rupture | ÷1.00 | 7.2.3, Table 26: fm consistent with the reinforcement and design life, PDF p108 · Not yet validated |
| Geosynthetic — pull-out | ÷1.30 | 7.2.4, Table 26, fp, PDF p109 · Not yet validated |
| Geosynthetic — sliding across | ÷1.30 | 7.2.4, Table 26, fs, PDF p109 · Not yet validated |
| Steel strip — rupture | ÷1.00 | 7.2.3, Table 26: fm consistent with the reinforcement and design life, PDF p108 · Not yet validated |
| Steel strip — pull-out | ÷1.30 | 7.2.4, Table 26, fp, PDF p109 · Not yet validated |
| Steel strip — sliding across | ÷1.30 | 7.2.4, Table 26, fs, PDF p109 · Not yet validated |
| Steel grid — rupture | ÷1.00 | 7.2.3, Table 26: fm consistent with the reinforcement and design life, PDF p108 · Not yet validated |
| Steel grid — pull-out | ÷1.30 | 7.2.4, Table 26, fp, PDF p109 · Not yet validated |
| Steel grid — sliding across | ÷1.30 | 7.2.4, Table 26, fs, PDF p109 · Not yet validated |