Analysis of Geo-Fluvial Parameters Affecting Riverbank Stability Through Physical Model Study

The stability of a river bank is significantly influenced by the geotechnical properties and geometrical features of the bank material. In the present study, extensive model tests have been conducted with the aim of investigating the effect of variations of slope of the bank, initial moisture content and bank material on its stability under rapid drawdown condition. This physical model study tried to simulate the post flood hydraulic and stability condition of the river bank during rapid drawdown of river stage. The bank material composed of soil collected from bank of river Ganga, Kaliachak, Malda district, West Bengal India. The paper presents the experimental results along with the computed values to highlights the effect of these parameters on its stability in terms of Factor of Safety (FOS) and depth of failure for different drawdown rates (R) and ratios (L/H). The results reveal that the shear strength loss is lesser for lower moisture content than that of higher moisture content of bank as it becomes more compacted due to seepage flow from river towards the bank during the of rise of water level. Slope of bank has obvious impact on its stability and type of bank material studied in this model tests have significant influence on variation of FOS during drawdown. Moreover, the results obtained in this study may help in predicting the stability conditions of a bank during design of any protection measures. Also, it is found that the reproducibility of physical model tests in the analysis of failure mechanism, causes and influence of various parameters on stability of river bank under a certain geo-fluvial environment may effectively been used for prototype analysis with assigned boundary condition.