Correlation between DPL, triaxial strength and CBR for the geotechnical evaluation of soils in the design of shallow foundations

Abstract

The mechanical characterization of soil is a fundamental aspect of shallow foundation design, particularly in areas with high geotechnical variability such as Baños del Inca, Cajamarca. This research aimed to establish quantitative correlations between the Dynamic Light Penetration (DLP) test, strength parameters obtained through triaxial tests, and California Bearing Ratio (CBR) values ​​in medium- to high-plasticity clay soils (CL–CH). A field and laboratory study was conducted, including DLP tests to representative foundation depths, the collection of samples for consolidated and undrained triaxial tests, and the determination of CBR under controlled compaction conditions. The results showed significant linear correlations between the blow count and CBR (R2 = 0.83), between DLP and the angle of internal friction (R2 = 0.79), and between CBR and undrained strength (R2 = 0.76). The incorporation of state variables such as moisture content and dry density improved the statistical fit to R2 = 0.87. It was observed that for values ​​greater than 15 blows/10 cm, the soils exhibited CBR values ​​greater than 20% and undrained compressive strengths greater than 118 kPa, indicating favorable conditions for conventional shallow foundations under the safety criteria established by Peruvian regulations. The results confirmed that the DPL can be used as a reliable preliminary tool to estimate strength and bearing capacity parameters in local clays, provided that the correlations are specifically calibrated for the site's geotechnical conditions.