Retaining & slopes · Anchors, nails & shoring
Soil nail verification / proof test calculator
Checks that the test reached the required multiple of the design load without pull-out or excessive creep, and back-calculates the minimum mobilised bond.
Standard: FHWA-NHI-14-007 soil nail testing · creep 6–60 min ≤ 2 mm
Open the live calculator → All retaining & slopes calculators
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Drill-hole diameter | 125 | mm |
| Bonded test length | 3 | m |
| Design load for the test length | 60 | kN |
| Test type | Verification (200 % DL) | |
| Maximum load held | 120 | kN |
| Displacement at 6 min | 8.2 | mm |
| Displacement at 60 min | 9.3 | mm |
| Ultimate bond assumed in design | 100 | kPa |
| Bar diameter | 25 | mm |
| Bar yield fy | 500 | MPa |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Required multiple of DL | 2.00 | |
| Required test load | 120.0 | kN |
| Creep 6–60 min | 1.10 | mm |
| Bar capacity 0.9·fy·Ab | 220.9 | kN |
| Mobilised bond Pmax/(πD·Lb) (lower bound) | 101.9 | kPa |
- ✓ Maximum load ≥ required test load
- ✓ Mobilised bond ≥ design ultimate bond
- ✓ Creep 6–60 min ≤ 2 mm
- ✓ Test load ≤ 90 % bar yield
Method, formulas and assumptions
- Required multiple of DL = IF(1=1,2,1.5) = 2
- Required test load = 2*60 = 120 kN
- Creep 6–60 min = 9.3-8.2 = 1.1 mm
- Bar capacity 0.9·fy·Ab = 0.9*500*PI()*25^2/4/1000 = 220.89 kN
- Mobilised bond Pmax/(πD·Lb) (lower bound) = 120/(PI()*125/1000*3) = 101.86 kPa
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.