Glossary¶
Geometry¶
| Symbol | Meaning |
|---|---|
| H | slope height [m] |
| β (beta) | slope face dip [°] |
| α (alfa) | failure plane dip [°] |
| ψ (psi) | upper face dip [°] |
| θ (theta) | tension crack dip [°] |
| T | distance of the tension crack from the crest [m] |
| B | block depth (length ⟂ to the section) [m] |
| L | length of the failure plane [m] |
| M | length of the upper bench [m] |
| Q | length of the tension crack [m] |
| A | wedge area per metre [m²] |
| W | weight per metre [kN/m] |
| O, B, C, D | wedge vertices (O = toe, B = crest, C = top of plane, D = top of TC) |
| xg, yg | centroid coordinates [m] |
Material¶
| Symbol | Meaning |
|---|---|
| γ (gamma) | unit weight of the block [kN/m³] |
| γw | water unit weight (9.81 kN/m³) |
| c | cohesion on the plane [kPa] |
| φ (phi) | peak friction angle [°] |
| φb | basic friction angle of smooth rock (Barton) [°] |
| JRC | Joint Roughness Coefficient [0–20] |
| JCS | Joint Compressive Strength [MPa] |
| ieff | roughness dilation = JRC · log₁₀(JCS/σn) [°] |
| σn | normal stress on the plane = N / L [kPa] |
Actions¶
| Symbol | Meaning |
|---|---|
| E | external load magnitude [kN/m] |
| δ (delta) | external load inclination [°] |
| kh = αs | horizontal seismic coefficient [-] |
| Ω (omega) | seismic direction [°] |
| Hw | ponded water level at toe [m] |
| Zw | water depth in the joint [m] |
| Zt | water depth in the tension crack [m] |
| U | uplift on the failure plane [kN/m] |
| V | water force in the tension crack [kN/m] |
| Up | ponded water force on the slope face [kN/m] |
Reinforcement¶
| Symbol | Meaning |
|---|---|
| J | active anchor pre-load [kN/m] |
| K | passive nail mobilised force [kN/m] |
| q | drape mesh normal pressure [kN/m²] |
| τR2 | cable panel resisting τ [kN/m] |
| F | single-element capacity [kN] |
| T | axial force in the anchor / nail [kN] |
| V | shear force in the nail (Clouterre) [kN] |
| Δ | reinforcement inclination [°] |
| Yt | head position on the slope face [m] |
Resistance and FS¶
| Symbol | Meaning |
|---|---|
| N | normal force on the failure plane [kN/m] |
| S | driving shear [kN/m] |
| τ | resisting shear strength [kN/m] |
| FS | factor of safety = τ / S |
| Fr | overturning safety factor (moments around toe) |
| Rsteel | bar yielding resistance [kN] |
| Rbond | bar↔grout bond resistance [kN] |
| Rpullout | bulb pull-out resistance [kN] |
| Rmin | governing limit [kN] |
| Rk | characteristic resistance = Rmin/ξ [kN] |
| Rd | design resistance = Rk/γRa,t [kN] |
| ξ | NTC Tab. 6.6.III factor (function of pull-out tests) |
| γRa,t | NTC §6.6 resistance factor (1.10 temp, 1.20 perm) |
Code factors¶
| Symbol | Meaning |
|---|---|
| γG | partial factor on permanent actions |
| γQ | partial factor on variable actions |
| γφ | partial factor on tan φ |
| γc | partial factor on cohesion |
| γR | partial factor on resistance |
| γE | partial factor on seismic actions (= 1.0) |
Code references¶
| Reference | Meaning |
|---|---|
| NTC 2018 | Italian Building Code (DM 17/01/2018) |
| Circ. 7/2019 | Italian Circular for the application of NTC 2018 |
| EN 1997-1 | Eurocode 7 — Geotechnical design |
| FHWA-NHI-09-035 | Soil Nail Walls Reference Manual (FHWA) |
| Hoek-Bray | Rock Slope Engineering (1981) |
| Barton-Bandis | non-linear shear strength of rock joints (1990) |
| Clouterre | French recommendations for soil nailing (1991/1993) |
| Bustamante-Doix | injected ground anchor calculation (1985) |