Failure risk analysis of riverbank ripraps with Monte Carlo simulation

The potential failure evaluation of river embankment structures such as ripraps, resulting from erosion or over-flows during flood events, is the main issue of their stability and safety assessment. Moreover, a changed sediment transport in rivers as a possible result of climate change influences the failure risk of riprap. This bank failure can lead to uncontrolled erosion and flooding with disastrous consequences in residential areas or damage of infrastructures. Thus, probabilistic analysis of failure mechanisms of ripraps due to flood events and sediment transport is a principal step to assess embankment stability. In this article, the concept of a probabilistic assessment model based on Monte Carlo simulation is presented to define the failure risk of bank protection by ripraps. This probabilistic simulation estimates the resistance of ripraps regarding the varied flood and sediment transport in future. The probability of failure in different modes such as direct block erosion, toe scouring and overtopping has been defined by taking into account the changed bed-load transport due to a probabilistic function of the design discharge. A sensitivity analysis was performed by varying slope, block size, bed-load characteristics, geometry of the cross section and hydraulic parameters. The failure probability of ripraps is assessed by a probabilistic function of the design safety factor.