Soil stress bulbs and settlement

What the tool calculates

• Isobars at 80%, 60%, 40%, 20% and 10% of applied pressure using Boussinesq and Newmark
• Depth of influence and settlement by layer, with soil modulus Es estimated from SPT data
• Warning for a compressible or soft layer within the stress bulb
• Superposition of stress increases from neighbouring foundations

What you enter

• Foundation geometry, depth and loading
• SPT profile by soil layer
• Neighbouring foundations, where present

What you receive

• Stress increase isobars
• Depth of influence
• Estimated settlement by layer

References and limits of applicability

• Boussinesq and Newmark elastic theory; assessment of allowable settlement should consider the guidance in ABNT NBR 6122:2019

Checks and considerations

• Compressible or soft layer within the stress bulb
• Interaction between neighbouring foundations

How it works

The stress increase field identifies the layers affected by loading and the influence of nearby foundations. Estimated settlement depends on the stiffness assigned to each layer. SPT correlations require the designer's assessment, particularly in soft or compressible soils.

Example of use

When comparing positions for two nearby foundations, enter their geometries and loads over the same soil profile. Examine overlapping stress bulbs and any compressible layers before assessing whether the resulting settlements are compatible.

Generated documents

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

• Geotechnical calculation report — Combine calculation reports for soil stress bulbs, retaining walls, reinforced soil walls, slope stability and soil-nailed slopes in one PDF. The document consolidates saved calculations without repeating or cross-checking the individual tools' verifications.