Dynamic driving formula — ultimate resistance from final setCasing → rock tool
Tip: any input below accepts comma-separated alternatives, e.g. 40, 50. Every combination is analysed and listed in the Alternatives table at the bottom of the page.
Record
1Hammer & energy
0–1
kN
1 tonne of ram ≈ 9.81 kN. Needed even in rated-energy mode (impact efficiency).
m
kJ
Manufacturer's energy per blow at the stroke used.
2Pile & impact
kN
m
mm²
mm
mm
kN
P = —
0–1
3Driving record — set
mm/blow
mm
4Temporary compression c
mm
c = cc + cp + cq, measured as elastic rebound of a blow trace.
mm
Typically 3–9 mm depending on dolly / packing.
mm
mm
Commonly taken as 2.5 mm.
cp = kp·Ru·L / (A·Ep) — solved simultaneously with the Hiley equation (quadratic in Ru).
m
mm²
GPa
Steel 205 · concrete ≈30–35 · timber ≈10
1.0 end-bearing · ≈0.5 uniform shaft friction
5Safety & target
2.5 is usual for Hiley with measured c; range 2–3.
kN
Ultimate driving resistance Ru
—kN
Allowable capacity Ra
—kN
Ru / FoS
Efficiency of blow ηb
—
Energy to pile
—kJ
Required set for target
—mm/blow
Formula
Ru =
ηh · ηb · W · hs + c / 2
with
ηb =
W + e²PW + P
− (W − eP)²(W + P)²
Resistance vs final set
How Ru falls as the pile drives more per blow, with the current operating point. Hover any curve (grey ones too) to read values; click a grey curve to select that case.