1998 Volume 51 Issue 4 Pages 11-20
The influence of soil water fluctuations on soil reinforcement by roots was examined with a model based on the de-formation of a pile inserted into soft subsoil. This model was applied to the results of a direct shear test using two materials that simulate a root system. One was a bamboo stick (0.27cm in diameter 10cm long), the other was a ny-lon net (0.05cm thick, 10cm wide, 15cm long). As soil sample, Toyora standard sand was used. The range of suc-tion in this test was from 0 to 50cm H2O.
The calculation results from this model corresponded well with the increase of shear stress by the direct shear test. The difference in the soil reinforcement between two materials was described in the relationship between the horizontal displacement and the shear stress increase. This difference was explained by the interaction between the subsoil deformation and the difference of the moment of inertia of the area between two materials in this model. This model has a parameter related to the elastic modulus of soil. The relationship between the parameter and the soil suction, the normal stress, explained the influence of suction on the shear strength of soil with a root system.
