Need advice on bearing capacity, settlement, and foundation recommendations with limited geotechnical test data
Hi everyone!
I’m currently helping prepare a geotechnical investigation report for a project with 5 boreholes, and I’d really appreciate some guidance from people with more experience in geotechnical design/reporting.
My professor is asking us to include the following in the final project output:
- nterpretation of results, conclusions, and recommendations
- Recommendations for the type of foundation
- Soil bearing capacity calculations for foundations
- Settlement assessment of critical areas
The challenge is that the investigation did not include UDS sampling, so we don’t have direct shear strength or consolidation test results.
The available data/tests are mainly:
SPT results
USCS classification
Sieve analysis
Hydrometer analysis
Atterberg limits
Specific gravity
Natural moisture content
Flexible-wall permeability
Groundwater observations
Borehole logs
There were no consolidation tests, UU/triaxial tests, UCS, or direct shear tests.
My initial thought is to use corrected SPT values and published correlations to estimate parameters such as friction angle for granular soils and possibly undrained shear strength for cohesive soils, then use these for preliminary bearing-capacity calculations.
For settlement, I understand that SPT-based methods can be used for granular soils, but I’m less confident about how to properly evaluate settlement in cohesive soils without consolidation parameters such as Cc, Cr, e0, and preconsolidation pressure.
I’d really appreciate advice on:
What methodology would you normally use with this level of available data?
Which SPT corrections/correlations would you recommend?
What parameters would you derive from the available tests?
How would you approach settlement for cohesive soils without consolidation testing?
Would you calculate bearing capacity per borehole, or group similar boreholes into geotechnical zones and use representative/critical BHs?
What additional information should I request from the structural/client side before starting, such as footing size, founding depth, column loads, or allowable settlement?
What references/books/standards would you recommend for learning how to do this properly?
I’m still learning and I want to make sure the analysis is technically defensible rather than just plugging numbers into equations.
Any advice, references, example workflows, or things I should watch out for would be greatly appreciated.
Thank you!
