Sensitivity analysis to examine tree root effectiveness in soft ground stabilisation
Native vegetation in Australia is becoming increasingly popular for stabilising railway corridors built over soft soils. A model previously developed to measure the rate of tree root water uptake and a computer model are used to investigate the effect of a wide range of soil, tree, and atmospheric parameters on partially saturated ground. First, sensitivity analysis is used to investigate the affect of different parameters on the maximum initial rate of root water uptake, and then a reference example is simulated using finite element analysis. The influence of parameters such as time, potential transpiration rate and its distribution factor, wilting point suction, the coefficient of permeability, and the distribution of root length density are studied. Soil suction and settlement was found to increase over time, with the effect being more significant in the first stages of transpiration. The most sensitive parameters are wilting point suction, the coefficient of saturation permeability at higher values, the rate of potential transpiration at lower values, and vertical root distribution when the coefficient is high.