Effect of Antecedent Rainfall on Slope Stability- A Case Study of Haflong Hill, North East India.

The accurate determination of factor of safety is important to find out the stability of slopes. Out of the many factors which are responsible for slope failure in hilly areas continuous rainfall, particularly, is one of the major important factor responsible for triggering landslide. Slope is an exposed ground surface that stands at an angle with the horizontal. In this study, a part of the hill of Haflong, the head quarter of Dima Hasao district in the state of Assam, India are chosen. Two types of transient analysis i.e., uncoupled analysis and coupled analysis were carried out. The coupled analysis considers the deformation of the soil surface with time when rain water passes through the soil mass. Three slope angles 30°, 45° and 90° were considered for both the case. The results shows that the factor of safety decreases with increase in the period of rainfall and slope angle, whereas the factor of safety increases slightly during coupled analysis which is due to the combined effect of deformation and seepage. [ABSTRACT FROM AUTHOR]