Foundations · Pile testing & NDT
Pile set-up from restrike testing calculator
Back-calculates the set-up factor A from end-of-drive and restrike capacities, then extrapolates the capacity at a design age.
Standard: Skov & Denver (1988): Q(t)/Q0 = 1 + A·log10(t/t0)
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 |
|---|---|---|
| Capacity at end of driving (EOD) | 1500 | kN |
| Capacity at restrike | 2360 | kN |
| Restrike time after driving | 14 | days |
| Reference time t0 (≈1 day clay, 0.5 day sand) | 1 | days |
| Design age | 100 | days |
| Design action E* | 1200 | kN |
| φg | 0.65 |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Set-up factor A = (Qr/Q0 − 1)/log10(tr/t0) | 0.500 | |
| Capacity at design age | 3,001 | kN |
| φg × restrike capacity (no extrapolated gain) | 1,534 | kN |
- ✓ A within the usual 0–1 range
- ✓ φg × restrike capacity ≥ E*
Method, formulas and assumptions
- Set-up factor A = (Qr/Q0 − 1)/log10(tr/t0) = (2360/1500-1)/LOG10(14/1) = 0.50023
- Capacity at design age = 1500*(1+0.50023*LOG10(100/1)) = 3000.7 kN
- φg × restrike capacity (no extrapolated gain) = 0.65*2360 = 1534 kN
- Rely on extrapolated set-up only where it is confirmed by later restrikes or static tests.
Related foundations calculators
- Pile driving formulas (Hiley / Gates) — Ultimate resistance from hammer energy and set; check against required capacity.
- Static pile load test (Davisson) — Load–settlement curve with the elastic line and Davisson offset to find the failure load.
- Dynamic pile test (PDA): CASE method capacity — From the force and velocity measured at the pile head at the peak (t1) and one wave return later (t1 +…
- Low-strain pile integrity test (PIT): length and impedance — Pile length from the toe echo time, depth of an anomaly, and the impedance ratio and equivalent diameter…
- Impulse response (mobility) test: length and impedance — Length from the spacing of resonant peaks in the mobility spectrum, and the equivalent diameter from the…
- Crosshole sonic logging: profile rating — Rates every reading of one tube-pair profile against the median first arrival time (FAT) and energy: Good ≤…
- Static pile load test interpretation — Load–settlement readings: Davisson offset limit load, 10 % of diameter criterion and Chin's hyperbolic…
- Bi-directional (O-cell) test: equivalent top-down capacity — Fits hyperbolas to two points on the upward (shaft) and downward (base) curves and adds them at a common…
- Thermal integrity profiling (TIP): effective diameter and cover — Converts the average temperature at an anomaly to an effective radius, estimates cover to the cage and the…
- Parallel seismic: unknown pile length — Fits straight lines to the first-arrival times above and below a trial break depth; the intersection…
For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.