Analysis of root reinforcement at slip surface.

In this paper. a theoretical model is proposed to investigate the behavior of tree roots subjected to mass movement and to determine the reinforcement capacity of tree roots at slip surface of landslide. Tree roots function as a type of reinforcement material to minimize landslide. By modelling a root system as a cluster of root fibers inserted through the unstable soil to the bedrock, the increase in the shear resistance of soil can be reliably estimated. Properties and distribution of the roots are taken from a number of previous field experiments. Roots used in the model are Japanese cedar (Criptomeria japonica) roots, the most popular species in Japan. With the inclined roots classified by inclinations and diameters, the relationship between reinforcement capacity of root fibers and horizontal displacements is analyzed under two main conditions: ultimate stress and pullout resistance. The computed results of the tree root model are used in the prediction of root reinforcement at slip surface of a previous soil-shear test. There is, in general, a reasonable agreement between predicted results and experimental data.