Investigating Root Geometry's Impact on Shear Strength in Non-cohesive Soils: A Discrete Element Analysis

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4. Investigating Root Geometry's Impact on Shear Strength in Non-cohesive Soils: A Discrete Element Analysis

ABSTRACT: This article presents a 2D numerical study on the effect of root geometry on the shear strength of non-cohesive soils. A discrete element model of the direct shear box test is developed, based on a molecular dynamics discrete element method with circular elements. The roots are modeled as chains of connected discs to mimic the behavior of a beam, capable of resisting tensile, shear, and bending stresses. Three samples are prepared by pluviation, one without roots and two with roots of different shapes, assumed to have the same cross-section and mechanical characteristics. The deposited samples are subjected to shear under confining stresses of 50, 100, and 200 kPa. The simulations accurately reproduce the characteristics of shear tests on non-cohesive rooted soils, showing an increase in shear strength without a peak resistance. The results indicate a significant increase in the characteristic angle of internal friction from 20.25° to 30.11° and 32.61°, and in the cohesion from 1.15 kPa to 15.42 kPa and 19.08 kPa for the two root forms, respectively. These findings demonstrate the crucial role of root morphology in enhancing the mechanical properties of non-cohesive soils, beyond just the effects observed in the shear stress-strain behavior. The comprehensive analysis, including the evaluation of Mohr-Coulomb parameters, highlights the importance of considering the structure of the root system when studying the mechanical behavior of vegetation-reinforced soils.

18th African Regional Conference on Soil Mechanics and Geotechnical Engineering (ARCSMGE2024)

Behavior of soils, analysis and modeling