Modeling shear strength parameters of tropical soils using dynamic resistance and physical properties in Penka Michel Cameroon

Abstract

This study develops predictive models for the shear strength parameters of tropical soils in Penka-Michel, Cameroon, based on measurements obtained from a lightweight dynamic penetrometer (LDP) and key physical soil properties. Tropical soils are characterized by pronounced variability in texture, density, and moisture sensitivity, which complicates geotechnical characterization and infrastructure design. To address these challenges, twenty in situ LDP tests were performed at representative locations, and ten undisturbed soil samples were collected for laboratory testing. Fundamental physical properties including particle size distribution, specific gravity, and consistency index were determined, and shear strength parameters (cohesion and internal friction angle) were obtained through direct shear testing. Multiple linear regression analysis was conducted to establish statistically relationships between dynamic resistance, physical soil properties, and shear strength parameters. The results show that the internal friction angle suggest the relationship with fine particles, specific gravity, consistency index, and dynamic resistance, yielding a coefficient of determination R2 = 0.87 and a mean absolute error (MAE) of 1.92°, indicating high predictive performance. Cohesion exhibits a moderate but statistically significant relationship with fine particles, specific gravity and dynamic resistance (R2 = 0.61, MAE = 0.0188 kPa). The validated models provide a rapid and cost-effective method for estimating essential geotechnical parameters during preliminary site investigations, thereby reducing dependence on extensive laboratory testing. These findings offer practical support for foundation design, slope stability analysis, and geotechnical planning in tropical regions, where soil heterogeneity and testing constraints often limit comprehensive characterization. Overall, this work contributes to more efficient geotechnical evaluation practices and improved infrastructure development strategies in tropical environments.