2009 Volume 46 Issue 1 Pages 27-34
Influence of the geometric elements (length“L”, thickness“D cos α ”and slope“α ”) and groundwater level of landslides on the c′ - tan φ′ diagram of stability analysis and the thrust force of landslide were studied by means of a model landslide, where the shift of average strength prameters at slip surface was also investigated.
Influences of L, D cos α , α and groundwater level on the c′ - tan φ′ diagram were discussed in relation to the alteration of c′ -tan φ′ line (c′ -intercept“c′ ”, tan φ′ -intercept“tan φ′ ”and inclination“β ”) . Obtained results were as outlined below. The influence of L is very minimal. D cos α has an effect on c′ and β , but has little impact on tan φ′ where as α has a significant impact on c′ and tan φ′ , but does not seem to have any effect on β . Influence of the geometric elements on the c′ - tan φ′ diagram was measured quantitatively and the importance of determining the slip surface was clarified futher. Influence of groundwater level appears as a large rightward shift of tan φ′ .
In the analysis of the alteration of average strength parameters at slip surface (c′ave , φ′ave ) and the thrust force of landslide corresponding to differences in relative positions of slip surface and groundwater table, two important observations were noted. A difference of one meter in the groundwater level has a significant impact on φ′ave , especially in the case of landslides having a small L, a steep α and a high groundwater level. A difference of one meter in the position of the slip surface has a significant impact on the percentage of change of thrust force, especially in the case of landslides having a small L and D cos α . Given these conditions, there are possibilities of change of thrust force by nearly 15 percent.
