The initiation of debris flow is related to mechanical properties of soil materials. Choosing Sanhe gully in Chonho, Chinshan area of Taipei County to take samples and find the particle-size-distribution curve. The author used “ weight replace method” to simulate field particle-size distribution curve, and carried out the isotropic consolidated-undrained triaxial test, triaxial permeability test, soil-water characteristic curve test and consolidated- drained triaxial test of unsaturated soil samples in order to realize the properties of mechanics, permeability and water retaining ability of the soil.
