Increase in shear modulus of soil due to tree root permeation and soil matric suction

1. Home
2. Publications
3. Online Library
4. Increase in shear modulus of soil due to tree root permeation and soil matric suction

The tree root permeated ground improvement methods are now being widely used around the world. Tree roots increase the stiffness of the soil by root reinforcement effect and soil suction effect. Shear modulus of soil is an important parameter in assessing the increase of shear strength of soil due to tree root permeation. Therefore, in this study the variation of shear modulus with respect to the variation of matric suction has been assessed and its trends has been identified according to the variation of the shear displacement. The shear modulus can be defined as how the material responds to shear stress and it is usually symbolized as `G`. Shear modulus (G), is directly proportional to the Youngs modulus (E) and inversely proportional to the Poissons ratio (). Youngs modulus (E) and Possions ratio (V) are directly influenced by root permeated effect. Shear modulus was calculated using the results obtained during the direct shear test carried out for soil only specimens and root permeated specimens. Direct shear tests were carried out under three different normal stresses and five different matric suction levels. Shear modulus increases with the increase in matric suction for both reinforced and unreinforced specimens. Further, the shear modulus of the reinforced sample is higher than the identical un-reinforced specimen. It can be observed that root permeated samples show more ductile behaviour than soil only specimens due to reinforcing effect of the roots in root permeated soil, from the plotted results between shear modulus over the shear displacement. This behaviour is important in Finite Element Modelling of the root permeated soil as the settlement evaluations are carried out using the stiffness of the materials. In this paper the variation of the shear modulus with matric suction in root permeated soil and its uses FEM modelling will be discussed.

9th International Congress on Environmental Geotechnics (ICEG2023)

Biogeotechnics and Bioremediation