IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 5 - FLUVIAL HYDRAULICS AND RIVER MANAGEMENT : Stochastic Analysis of Contraction Scour in Cohesive Soils
Stochastic Analysis of Contraction Scour in Cohesive Soils
Author : Ricardo A. Gonz lez Flores, Luigia Brandimarte, Giuliano Di Baldassarre and Arthur Mynett
Abrupt contractions are frequently encountered along watercourses as a result of either natural catastrophic events (e.g., tree fall, landslides, river bank failures, etc.) or of the construction of bridges and control sections. In the case of gentle slope channels, the velocity increases through the contraction. Depending on the shear strength of the bed sediments, the larger flow velocity may scour the river bed with a consequent increase in water depth at the contraction until the shear stress exerted by water flow is reduced below the shear strength of the bed material. Thus, after the stream width is locally reduced, the riverbed undergoes a local adjustment, leading to the development of a scour hole. In the case of cohesionless bed material, this transient can be relatively short. Conversely, in the case of cohesive bed, because of the physiochemical interactions between colloidal particles in fine-grain soils the scour progresses at a slower pace. This implies that a realistic scour depth assessment should be based on the analysis of a long sequence of river flows. Because of the limited length of the historical records, stochastic techniques can be used to generate longer series of stream discharges.This research work aims at understanding the behavior of contraction scour in cohesive soils along the lifetime of the structure, by analyzing the sensitivity of the variables playing a role in the scour process. A Monte Carlo approach is used to establish the probability density function and exceedance probability of the estimated scour depth values for different expected lifetime of the structure.
File Size : 595,433 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Date Published : 18/07/2016
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