Bearing capacity of belled caissons (tubulões)

What the tool calculates

• Berberian method: σₐ = NSPT/K, with the factor of safety already included in K
• Centred or property-boundary configuration, with reaction increased to account for eccentricity
• Warnings for a weak layer below the base and settlement above the limit
• Influence zone extending 1.5B below the base

What you enter

• SPT profile and founding depth
• Caisson base geometry and load
• Centred or property-boundary configuration

What you receive

• Allowable bearing pressure from the Berberian method
• Comparison with theoretical methods
• Increased reaction for the property-boundary configuration

References and limits of applicability

• ABNT NBR 6122:2019 + Emenda 1:2022 — Foundation design and construction

Checks and considerations

• Weak layer within the influence zone (1.5B)
• Settlement above the limit

How it works

The Berberian method calculates allowable bearing pressure from the SPT N-value and the selected soil coefficient K, without reapplying the factor of safety already included in that coefficient. Comparisons with other methods must respect their limits of applicability and the warnings for weak layers and settlement. Soil bearing capacity and structural design are separate checks.

Example of use

When studying a caisson near a property boundary, enter the borehole data, load and base geometry. Compare the boundary and centred configurations, then examine the increased reaction, the bearing stratum and any weak layers beneath it.

Generated documents

These documents are assembled within your project using data from the corresponding tools.

• Foundation calculation report — Combine the project's SPT logs, bearing capacity calculations and structural designs for piles, pile caps, footings and belled caissons in one PDF. The document consolidates selected items; technical checks remain within each tool.