Time evolution of the flow characteristics around bridge abutments during scouring process

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: BURHAN YILDIZ

Eş Danışman: METE KÖKEN, MUSTAFA GÖĞÜŞ

Özet:

This study involves numerical and experimental investigation of the velocity field and the time evolution of the scour pattern forming around bridge abutments. The experimental part of the study includes velocity field recordings by using an ADV device and eroded bed bathymetry measurements by an ultrasonic ranging system. Using the ADV measurements; the velocity components, the upstream part of the primary vortex and the change of downstream recirculation region dimensions by the change in abutment length, type and closeness to the channel bed was investigated. Scour recording part of the experimental study included scour pattern recordings for various abutment lengths, types and experiment durations; and continuous measurements of scour at some predefined sections around abutments for eight hours. Maximum scour depth, scour hole dimensions and scour volume are related to scour time and abutment length. It was observed that, the contraction scour occurs together with the local scour at contraction ratios larger than 15-20% depending on the abutment type. The second part of the study includes a numerical analysis of the problem by using a commercially available CFD software. The numerical analysis consisted of simulations both for non-erodible and erodible channel bed conditions. The capability of the scour model of the software was tested.