Authors : G.H. Bibalani and B. Majnounian
Abstract: Slope instability due to landslides is particularly common in N Iran. It is possible to fight against these hazards thanks to the roots of scrubs, which provide an important contribution towards the stability of hillslopes. However, knowledge on the effectiveness of roots for slope stability needs improvement. Therefore, a study has been carried out on the effect of roots on slope stability, in particular for Gleditshia sp. The study area was located in Roudsar Township, in Gilan Province of N Iran. Some parts of this area cover with Gleditshia sp. forest tree. Soil samples with and without roots of the mentioned specie were taken, on an area of approximately 30 ha large, for testing in the laboratory. Soil shear tests were carried out on these samples and the Factor of Safety (FS) was calculated. Results showed that the FS was increased in soils with roots present. The global slope FS was then determined using Bishop�s method. We calculated FS in order to protect slopes where the gradient exceeds 25%. In this case study, minimum FS which corresponds to Gleditshia sp. vegetation with greater than 60% crown cover, a soil internal friction angle of 15� and a slope angle of 18�. When soil internal friction angle equals 19� and slope angle is more than 23�, slope stability can not be increased by Gleditshia sp. species.
G.H. Bibalani and B. Majnounian , 2007. Protection Roles of Gleditshia Caspica Dsf. on Slopes in Iran . Research Journal of Biological Sciences, 2: 713-717.