Performance of culverts under flooding conditions

Onabule, Oluwatosin Abdulfatai (2015) Performance of culverts under flooding conditions. MSc dissertation, University of Portsmouth.

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    A lot of research work has been done to improve the design overtime in terms of effectiveness, cost and efficiency. Hydraulic design of a culvert is based upon the characteristics of a barrel flow (free surface flow, orifice flow or pipe flow)conditions which depend on its length, roughness, gradient and upstream and downstream water levels.
    This research however looked into the effect of culvert shape, bed slope and size so as to be able to make recommendations based on the design of culvert given in the CIRIA guide.
    This was achieved by carrying out 2 sets of experiment, one on rectangular culverts and the other on the circular using a small flume and a large flume respectively. A wooden rectangular model was used with different inlet shape and barrel depths of 15mm, 25mm and 35mm. This first set of experiment was also carried to assess the impact of bed slope on the performance of culverts by using bed slopes of 0%, 0.25%, 0.5%, 0.75% and 1% and the corresponding flow rates and water depths at the upstream, culvert inlet, culvert outlet and downstream were recorded.
    The second set of experiment was with the circular culvert model which was used with the big flume. The water depths at the upstream, culvert inlet and downstream were also recorded corresponding to the measured flow rate. The bed slopes were then also varied to assess the effect of bed slope on performance of culverts as in the rectangular experiment.
    Culverts will perform better with steeper slopes. This in actual construction might the difficult to achieve as culverts are usually designed to blend with the environment which means that slope of culverts will usually conform to the bed slope of the channel. However, the bed slope of the channel can be altered to achieve the required bed slope of the culvert but will require the use of a coffer dam during construction
    Furthermore, rectangular culverts perform better under the rounded inlet edge as compared to the rectangular inlet edge which is contrary to previous studies. This study also indicated that irrespective of the bed slope, circular culverts design can pass successfully floods of up to 135% of the design flow with relatively small afflux

    Item Type: Dissertation
    Departments/Research Groups: Faculty of Technology > School of Civil Engineering and Surveying
    Depositing User: Jane Polwin
    Date Deposited: 12 Nov 2015 16:34
    Last Modified: 12 Nov 2015 16:34

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