Analysing Soft Ground Improvement Caused by Tree Root Suction

Bioengineering aspects of native vegetation are currently being evolved to improve soil stiffness, slope stabilisation, and erosion control. Vegetation contributes to weak soil stabilisation through reinforcement of the soil, dissipation of excess pore pressures, and increasing the shear strength by induced matric suction. This paper looks at the way that vegetation influences soil matric suction, shrinkage, and ground settlement. A theoretical model previously developed by the authors for the rate of tree root water uptake together with an associated numerical simulation is used in this study. A conical shape is considered to represent the geometry of the tree root zone. Based on this proposed model, the distribution of moisture and the matric suction profile adjacent to the tree are numerically analysed. Field measurements taken from previously published literature are compared with numerical predictions for further validation. The predicted results compared favourably with the measured results, justifying the assumptions upon which the model was developed. It is desirable to consider the influence zone of tree roots and the improved soil properties in modern geotechnical designs, benefiting from native vegetation.