API: vertical pile group

Computes separately named ultimate, ASD allowable, optional LRFD factored, and service-load quantities. Ultimate group resistance is the lesser of the summed single-pile and equivalent-block modes. The currently released settlement method is the USACE sand-group factor and therefore rejects clay, rock, and mixed profiles. The method and every input are explained in Pile groups; the same analysis runs interactively at the groups tool.

Endpoint

The request is an axial request (same pile and typed soil layers) plus a rectangular layout: nx × ny piles at center-to-center spacingX / spacingY. It also requires an explicit serviceLoad, factorOfSafety, and named settlementMethod.

Authentication, rate limits, and the error envelope are shared by every endpoint — see the API overview. Requests are unit-agnostic: any self-consistent unit system works, and results come back in the same units. The examples below use SI (m, kN, kPa, kN/m³).

Request fields

This table is generated from the same schema that validates the request, so it cannot drift. Where a field appears once per variant row, it belongs to that variant only.

Response fields

Code examples

A complete, runnable request. Replace YOUR_API_KEY (or set PILECALC_API_KEY in your environment).

curl https://api.pilecalc.com/v1/group-vertical \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "unitSystem": "si",
  "pile": {
    "kind": "uniform",
    "length": 18,
    "diameter": 0.61,
    "elasticModulus": 30000000,
    "unitWeight": 24,
    "displacement": true
  },
  "soil": {
    "layers": [
      {
        "type": "cohesionless",
        "top": 0,
        "bottom": 8,
        "gamma": 18,
        "phi": 31
      },
      {
        "type": "cohesionless",
        "top": 8,
        "bottom": 18,
        "gamma": 19.5,
        "phi": 35
      }
    ],
    "waterTableDepth": 3,
    "waterUnitWeight": 9.81
  },
  "layout": {
    "nx": 3,
    "ny": 3,
    "spacingX": 1.83,
    "spacingY": 1.83
  },
  "serviceLoad": 2500,
  "factorOfSafety": 3,
  "settlementMethod": "usace-sand-group-factor",
  "resistanceFactor": 0.65
}'

The GET variant returns governingUltimate,allowableResistance,serviceSettlementGroup as a plain-text CSV line — made for Excel's WEBSERVICE() and Sheets' IMPORTDATA() (see Use PileCalc in Excel). Omit fields to get the full JSON response.

Interpreting results

• governingUltimate is not an allowable load. Use allowableResistance for the declared ASD basis or factoredResistance for the requested LRFD resistance factor.
• Compare serviceSettlementGroup against the serviceability limit and verify that serviceLoad matches the intended working combination. The response includes convergence evidence; settlement is never evaluated at an implicit capacity.
• Pile-cap contribution is not included; the result is the piles alone.
• Cohesive, rock, and mixed profiles are rejected until a named consolidation/equivalent-pier method is implemented and independently benchmarked.