Declining River Levels Riverbank Stability Analysis

January 10, 2011

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Students at Adelaide University recently undertook an analysis of the effects of declining river levels on the stability of adjacent riverbanks. Such an analysis made use of the following aspects of the SVFlux™ / SVSlope® software:

  • Unsaturated analysis
  • Coupled stability and seepage analysis

Recent upgrades to computing technology allow SoilVision software to accurately model long term slope stability. Two software packages were used, SVFlux™ for seepage modeling and SVSlope® for calculating slope stability. For the case of a lowering water level along a riverbank; the shear strength along failure plane, in unsaturated zone, increases as water level decreases, and collapse of riverbank is due to other mechanisms, not rotational failure. The research presented examines modelling the effect of declining water levels on the stability of riverbank slopes. Where; climatic factors, geometry of the slope, material properties of the soil and time taken to vary water level all influenced the stability of the slope. The contribution of soil suction to shear strength was considered. The drying of the soil to increase the shear strength and wetting of the soil to decrease the shear strength, However the influence of unsaturated shear strength was lessened by the presence of a high groundwater table. As the method of unsaturated shear strength decreases the likelihood of a conservative solution it is important to ensure that the model parameters are accurate as this can lead to underestimated factors of safety.

The analysis by students was a good example of an advanced type of analysis being accomplished easily with the SVFlux/SVSlope software products.

Read the original PDF here