Foundations · Pile testing & NDT
Crosshole sonic logging: profile rating calculator
Rates every reading of one tube-pair profile against the median first arrival time (FAT) and energy: Good ≤ 10 % / < 6 dB, Questionable ≤ 20 % / < 9 dB, Poor/Flaw ≤ 30 % / < 12 dB, otherwise Poor/Defect.
Standard: ASTM D6760 · FAT increase / energy reduction rating (Good, Questionable, Poor/Flaw, Poor/Defect)
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 |
|---|---|---|
| Tube spacing (centre to centre) | 0.8 | m |
| Readings: depth (m), FAT (μs), relative energy (dB) | 1, 200, -0.4 2, 200, -1.3 3, 200, -0.2 4, 198, -1.0 5, 200, -0.3 6, 199, -0.6 7, 200, -0.4 8, 201, -1.5 9, 200, 0 10, 202, -0.5 11, 250, -10.0 12, 224, -5.0 13, 200, -0.3 14, 198, -1.3 15, 200, -0.2 16, 198, -0.1 17, 200, -0.5 18, 201, -1.4 19, 200, -0.2 20, 202, -0.9 |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Median FAT (sound concrete reference) | 200.0 | μs |
| Median energy | -0.500 | dB |
| Median velocity s/FATm | 4,000 | m/s |
| Questionable readings | 1.00 | |
| Poor/Flaw readings | 1.00 | |
| Poor/Defect readings | 0.000 | |
| Depth of worst reading | 11.00 | m |
| Worst FAT increase | 25.00 | % |
- ✓ Median velocity ≥ 3500 m/s (sound concrete)
- ✗ No Poor/Flaw or Poor/Defect readings
Method, formulas and assumptions
- Median FAT (sound concrete reference) = MEDIAN([t.fat]) = 200 μs
- Median energy = MEDIAN([t.en]) = -0.5 dB
- Median velocity s/FATm = 0.8/200*1000000 = 4000 m/s
- Questionable readings = COUNTIF([p.rt],"=2") = 1
- Poor/Flaw readings = COUNTIF([p.rt],"=3") = 1
- Poor/Defect readings = COUNTIF([p.rt],"=4") = 0
- Depth of worst reading = INDEX([p.z],MATCH(MAX([p.inc]),[p.inc],0)) = 11 m
- Worst FAT increase = MAX([p.inc]) = 25 %
- Rate each tube pair separately and correlate anomalies across pairs; confirm Poor/Defect zones by tomography or coring.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.