Standard Penetration Test and Dynamic Cone Penetration Test Relationship for Coarse-Grained Soils

The Standard Penetration Test (SPT) is a commonly used and effective disturbed sampling in-situ method to obtain the strength characteristics of soils, providing significant results for geotechnical design. Several correlations between SPT blow counts (N value) and soil behavior have been established to define physical and mechanical properties, supporting the determination of design parameters for soil layers. Similarly, the Dynamic Cone Penetration Test (DCPT) is a feasible and cost-efficient method for assessing soil characteristics, providing continuous and time-conscious data. Obtaining correlations between SPT and DCPT can enhance data acquisition by leveraging the strengths of both methods. This study investigates the relationship between SPT and DCPT results for coarse-grained soils through a comprehensive site investigation conducted various locations in the Kingdom of Saudi Arabia (KSA) for a renewable energy project. The test points were almost identical, and a density-based relationship between SPT blow counts and DCPT penetration resistance was developed. Individual evaluation of relationship between SPT and DCPT conducted in site-specific conditions and the correlation of all sites combined and generalized together. The comparison of the proposed correlation and existing studies were utilized on similar conditions to validate reliability. An evaluation was made to correlate SPT-N&DCP (Blow/100mm) values with the results obtained from SPT&DCPT tests performed at four project sites. The correlation varies between 0.56 and 0.70. Combination of all sites calculated as 0.72. This research presents precious perceptions into incorporating SPT and DCPT data to optimize geotechnical design practices.