Managing C = 0 in Geotechnical Reports: A Practical Approach Using Envirocalc
In recent geotechnical assessments, it has become common to see a cohesion value (C) of zero recommended for foundation soils. While this conservative assumption is valid in certain conditions, it can have a significant downstream impact on structural design.
WHY DOES C=0 MATTER
Cohesion contributes to the resistance against sliding and bearing failure, particularly under long-term loading. If cohesion is assumed to be zero:
Resistance values drop considerably.
Foundations may require significant upsizing to meet stability criteria.
Designs become overly conservative, increasing both construction cost and material use.
A COST EFFECTIVE SOLUTION: COMPACTED HARDFILL
Introducing a compacted hardfill layer beneath the foundation can help restore lost cohesion and provide the necessary resistance. The key is to determine the minimum cohesion value needed to achieve an efficient design.
HOW ENVIROCALC HELPS
Envirocalc provides engineers with the flexibility to:
Manually input cohesion values to model compacted hardfill or site-specific soil improvements.
Check sliding and bearing resistance instantly under various scenarios.
Fine-tune designs to optimise performance and cost without compromising safety.