Bioengineering ground improvement considering root water uptake model

Bioengineering features of native vegetation are currently being evolved to enhance soil stiffness, slope stabilisation and erosion control. The effects of tree roots on soil moisture content and ground settlement are discussed in this paper. Matric suction induced by tree roots is a key factor, governing the properties of unsaturated soils, directly imparting stability to slopes and resistance for yielding behaviour. A mathematical model for the rate of root water uptake that considers ground conditions, type of vegetation and climatic parameters has been developed. This study highlights the inter-related parameters contributing to the development of a conceptual evapo-transpiration and root moisture uptake equilibrium model that is then incorporated in a comprehensive numerical finite element model. The developed model considers fully coupled-flow-deformation behaviour of soil. Field measurements obtained by the Authors from a site in Victoria, South of Australia, are used to validate the model. In this study, the active tree root distribution has been predicted by measuring soil organic content distribution. The predicted results show acceptable agreement with the field data in spite of the assumptions made for simplifying the effects of soil heterogeneity and anisotropy. The results prove that the proposed root water uptake model can reliably predict the region of the maximum matric suction away from the tree axis.