Author(s): Junke Guo
Keywords: Bridge scour; clear-water scour; pressure flow; real-time monitoring; submerged flow; time-dependent scour
Abstract: The current design of bridge foundations based on equilibrium scour depths is much larger than the real maximum scour depth since peak flood periods are often too short to reach equilibrium conditions. Based on a tested hypothesis on the time rate of scour, this research presents a power-exponential equation for the time-dependent clear-water scour depth including a nonzero initial condition for submerged bridge flows. For zero initial conditions, the proposed equation is reduced to a log or power law during the initial phase and an exponential decay near the equilibrium condition. The proposed equation reduces design depths according to design flows and their peak periods, translating into significant savings in the construction of bridge foundations. With a real-time monitoring system, the proposed equation also predicts time-series scour depths during floods, helping bridge managers formulate timely corrective strategies.