ABSTRACT
Annually, river bank mass failures destroy much fertile soil and lead to the collapse of nearby infrastructure around the world. The angle of riverbanks after planar failure, a more common type of river bank mass failures, plays an important role in defining the geometry of a failed block when analyzing the stability of the banks against planar mass failure. In this research we carried out a set of tests on a physical model of a river bank, consisted of two layers of soil, and measured the failed angle of the bank soil layers when failure was observed. Based on the observed data, we introduced two relationships to estimate the amount of upper and lower bank failure angles. By taking the mean values of the physical and mechanical specifications of the two layers; i.e. imagine a homogenous river bank, a new relationship was also introduced and its results compared with those obtained from available relationships The results showed that the river bank angle after planar mass failure is better estimated using the new relationship and it can be used to estimate the angle of the river bank for both multilayered and homogenous river banks.
