Static-analysis capacity of a single pile through up to three soil layers: skin friction plus end bearing, nominal and factored, with a capacity-vs-depth curve. Driven piles use the API α-method in clay and the Meyerhof SPT method in sand; bored piles (drilled shafts) use the AASHTO α-method in clay and the O’Neill–Reese β-method in sand.
Static-analysis capacity of a single pile through up to three soil layers: skin friction plus end bearing, nominal and factored, with a capacity-vs-depth curve. Driven piles use the API α-method in clay and the Meyerhof SPT method in sand; bored piles (drilled shafts) use the AASHTO α-method in clay and the O’Neill–Reese β-method in sand.
The pile tip may sit inside any layer; layers below the tip only matter if you deepen the pile. Bored piles ignore shaft friction in the top 1.5 m and the bottom one diameter in clay (GEC-10).
Defaults follow AASHTO Table 10.5.5.2.3-1 / 10.5.5.2.4-1: driven static analysis φ ≈ 0.35; bored shafts φside ≈ 0.45–0.55, φtip ≈ 0.40–0.50 depending on soil and method. Adjust to your jurisdiction.
| Segment | Method | fs avg (kPa) | R (kN) |
|---|
Static-analysis capacity is a preliminary number, not a design guarantee — on real jobs it gets confirmed or replaced by load tests, PDA/CAPWAP on driven piles, or Osterberg cells on large bored shafts, and the resistance factor rises with the quality of that verification (that is the whole logic of AASHTO Table 10.5.5.2.3-1). A few habits worth keeping: the Meyerhof SPT numbers here assume displacement piles — halve the shaft friction for H-piles; the O’Neill–Reese β already bakes depth into the coefficient, so resist the urge to also cap σ′v; and in the Gulf the layer that matters is usually the weak calcareous siltstone/mudstone below the sand — treat it as a cohesive material with a lab-derived Su rather than pushing the sand correlations past their range. Group effects, downdrag, uplift and lateral response are separate checks this tool deliberately leaves out.
The soil mechanics do not change with the code: the shaft friction and end bearing are still found with the same α, β and SPT correlations through the layers you set. What changes is how that calculated resistance becomes a design value. Under Eurocode, EN 1997-1 divides the shaft and base parts by partial resistance factors that depend on the Design Approach; the tool uses Design Approach 2, where the factors for driven and bored piles are both 1.1 in the recommended set. Because the capacity comes from a calculation with ground parameters rather than from load tests or ground-test profiles with correlation factors, a model factor is added on top. Its value is set nationally; the tool uses 1.4, so the overall reduction is about 1/1.54 = 0.65.
Under KDS, KDS 24 14 51 works like AASHTO: each part of the resistance is multiplied by a resistance factor that depends on the pile type, the soil and the method. The factors are fixed by the code rather than chosen with the sliders, and they are applied layer by layer, so a driven pile gets 0.35 on clay and 0.30 on sand (SPT method), while a bored pile gets 0.45 / 0.40 in clay and 0.55 / 0.50 in sand for shaft / tip. For driven piles in sand these are lower than the 0.45 typical AASHTO default, so the KDS factored capacity is usually the smallest of the three.