Reliability-Based Assessment of Scour Below Spillways

The available equations for scour prediction below spillways are mostly deterministic in nature, which do not consider uncertainties of various scouring parameters adequately. A reliability-based assessment of the scour in such situations is of paramount importance in examining the relationship between safety factor and reliability, which are considered to be the key parameters for decision-making in the foundation design. In this paper, a methodology for the reliability assessment of scour downstream of a spillway has been presented using a Spreadsheet-Cell-Object-Oriented Algorithm (SCOOA) for the First Order Reliability Method (FORM). To study the influence of various random variables on the reliability against scouring sensitivity analysis has been carried out. To achieve desirable safety level in the design of the structure foundation reliability based safety factors have also been proposed. The influence of correlation among the random variables on the reliability has also been studied.