Assessing the influence of root reinforcement on slope stability by finite elements

Y H Chok,W S Kaggwa,D V Griffiths,M B Jaksa

doi:10.1186/s40703-015-0012-5

Abstract

This paper aims to investigate the effect of root reinforcement on slope stability using finite element methods. It is well recognised that plant roots can improve the shear strength of soils by their high tensile strength and closely spaced root matrix system. The increase in soil shear strength due to root reinforcement is considered as an increase in apparent soil cohesion, called root cohesion, c r . In this paper, a freely available ( http://www.inside.mines.edu/~vgriffit/slope64 ) finite element code called slope64 described by Griffiths and Lane (Geotechnique 49(3):387–403, 1999) is used to model the effect of root reinforcement on slope stability. The root cohesion is added directly to the soil cohesion for the soil elements that are reinforced by plant roots. The results from the finite element analyses demonstrate that the factor of safety of a slope increases when the effect of root reinforcement is taken into consideration. A series of stability charts are developed which can be used for assessing the influence of root reinforcement on slope stability.

Highlights

Plant roots can reinforce the soil due to their tensile strength and adhesional properties
This paper aims to investigate the effect of root reinforcement on slope stability using finite element methods
The results from the finite element analyses demonstrate that the factor of safety of a slope increases when the effect of root reinforcement is taken into consideration

Summary

Introduction

Plant roots can reinforce the soil due to their tensile strength and adhesional properties. The inclusion of plant roots with high tensile strength increases the confining stress in the soil mass by its closely spaced root matrix system. The soil mass is bound together by the plant roots and the soil shear strength is increased by providing additional apparent cohesion to the soils [2,3,4,5]. Plant roots have a negligible effect on the friction angle of soils due to their random orientation [6]. The enhanced soil shear strength due to root reinforcement can be considered equivalent to the increase in apparent soil cohesion, cr. The Mohr–Coulomb equation for soil shear strength can be modified as follows [2]:

Objectives

Findings

Discussion

Conclusion