Why is a Geotechnical Investigation Necessary to Verify Soil Bearing Capacity?

A geotechnical investigation is essential because it provides the site-specific data required to identify competent bearing strata and accurately size helical pier systems. Relying on general benchmarks is insufficient because actual soil bearing capacity varies significantly based on moisture content, density, and stratification.

Performing a thorough investigation—including soil borings and Standard Penetration Tests (SPT)—allows us to:

• Identify Soil Properties: We determine if the soil is cohesive (like clay, where undrained strength dictates capacity) or granular (like sand or gravel, where the friction angle is the primary variable).
• Establish Design Parameters: The data gathered informs the selection of helix plate diameter, the number of helices, and the required embedment depth to ensure structural loads are safely transferred to stable ground.
• Evaluate Environmental Factors: Investigations identify groundwater fluctuations and regional challenges, such as expansive clays, which can reduce effective soil strength or cause volume changes that impact long-term stability.
• Calibrate Field Measurements: While we monitor installation torque in real-time to estimate capacity, those readings must be calibrated against the specific soil profile identified in the geotechnical report to ensure accuracy.

For every project, we recommend you consult a structural engineer or our engineering team for project-specific design and installation guidance to ensure compliance with building codes and ICC-ES AC358 acceptance criteria.

• How to Calculate Soil Bearing Capacity for Helical Piers